HEAT PUMP SYSTEM REVERSING VALVE FAULT DETECTION

Abstract

A method of operating a heat pump system includes performing two or more status checks of a reversing valve. Each status check includes comparing a respective set of measurements. The method further includes determining whether the reversing valve is in a fault condition based on at least one of the plurality of status checks.

Claims

1. A method of operating a heat pump system, the heat pump system comprising an outdoor portion, an indoor portion, and a sealed system coupled between the outdoor portion and the indoor portion to circulate refrigerant through an indoor heat exchanger of the indoor portion and an outdoor heat exchanger of the outdoor portion, the sealed system comprising a reversing valve to selectively reverse flow direction of the refrigerant, the method comprising: performing a first status check of the reversing valve by comparing a first set of sensor measurements; performing a second status check of the reversing valve by comparing a second set of sensor measurements; and determining whether the reversing valve is in a fault condition based on at least one of the first status check and the second status check.

2. The method of claim 1, wherein determining whether the reversing valve is in the fault condition comprises determining the reversing valve is in the fault condition based on both of the first status check and the second status check.

3. The method of claim 1, wherein the first set of sensor measurements is obtained from a first temperature sensor and a second temperature sensor, and wherein the second set of sensor measurements is obtained from the first temperature sensor and a third temperature sensor.

4. The method of claim 1, wherein the first set of sensor measurements is obtained from a first temperature sensor and a second temperature sensor, and wherein the second set of sensor measurements is obtained from a third temperature sensor and a fourth temperature sensor.

5. The method of claim 1, wherein the first set of temperature measurements and the second set of temperature measurements are obtained from a plurality of sensors, further comprising performing a validation check for each sensor of the plurality of sensors by validating at least one measurement value from each sensor of the plurality of sensors, wherein each sensor measurement of the first set of sensor measurements and the second set of sensor measurements is obtained from a sensor which passed the validation check.

6. The method of claim 1, further comprising performing a validation check for each sensor measurement of the first set of sensor measurements and the second set of sensor measurements, wherein the fault condition of the reversing valve is determined based on only the first status check when each sensor measurement of the first set of sensor measurements passes the validation check and at least one sensor measurement of the second set of sensor measurements does not pass the validation check, and wherein the fault condition of the reversing valve is determined based on only the second status check when each sensor measurement of the second set of sensor measurements passes the validation check and at least one sensor measurement of the first set of sensor measurements does not pass the validation check.

7. The method of claim 1, wherein the first status check returns a fault status and the second status check returns a normal status, further comprising performing a third status check by comparing a third set of sensor measurements, wherein the third status check returns a fault status, and wherein determining whether the reversing valve is in the fault condition comprises determining the reversing valve is in the fault condition based on the first status check and the third status check.

8. The method of claim 1, wherein the first status check returns a fault status and the second status check returns a normal status, further comprising performing a third status check by comparing a third set of sensor measurements, wherein the third status check returns a normal status, and wherein determining whether the reversing valve is in the fault condition comprises determining the reversing valve is not in the fault condition based on the second status check and the third status check.

9. The method of claim 1, further comprising waiting for the heat pump system to stabilize at a steady state of operation prior to performing the first status check and performing the second status check.

10. The method of claim 1, wherein the first set of sensor measurements comprises a first one and the second set of sensor measurements comprises a second one of the following sets: indoor air outlet temperature and indoor air inlet temperature; indoor coil temperature and indoor air inlet temperature; outdoor coil temperature and outdoor air inlet temperature; indoor coil refrigerant pressure and indoor air inlet temperature; outdoor coil refrigerant pressure and outdoor air inlet temperature; indoor coil temperature and outdoor coil temperature; and indoor coil refrigerant pressure and outdoor coil refrigerant pressure.

11. A method of operating a heat pump system, the heat pump system comprising an outdoor portion, an indoor portion, and a sealed system coupled between the outdoor portion and the indoor portion to circulate refrigerant through an indoor heat exchanger of the indoor portion and an outdoor heat exchanger of the outdoor portion, the sealed system comprising a reversing valve to selectively reverse flow direction of the refrigerant, the method comprising: obtaining a plurality of measurements from a plurality of sensors in the heat pump system; performing a plurality of status checks, wherein each status check comprises comparing a respective set of measurements from the plurality of measurements; and determining whether the reversing valve is in a fault condition based on the plurality of status checks.

12. The method of claim 11, further comprising performing a validation check on each measurement of the plurality of measurements prior to performing the plurality of status checks, wherein each set of measurements consists of only measurements that passed the validation check.

13. The method of claim 11, wherein obtaining the plurality of measurements comprises obtaining a first measurement from a first sensor, a second measurement from a second sensor, and a third measurement from a third sensor.

14. The method of claim 11, wherein the plurality of status checks comprises a first status check comparing a first set of measurements, a second status check comparing a second set of measurements, and a third status check comparing a third set of measurements.

15. The method of claim 14, wherein determining whether the reversing valve is in the fault condition based on the plurality of status checks comprises determining whether the reversing valve is in the fault condition based on a majority of the plurality of status checks.

16. The method of claim 11, further comprising waiting for the heat pump system to stabilize at a steady state of operation prior to obtaining the plurality of measurements.

17. The method of claim 11, wherein each status check of the plurality of status checks comprises comparing one of the following sets of measurements: indoor air outlet temperature and indoor air inlet temperature; indoor coil temperature and indoor air inlet temperature; outdoor coil temperature and outdoor air inlet temperature; indoor coil refrigerant pressure and indoor air inlet temperature; outdoor coil refrigerant pressure and outdoor air inlet temperature; indoor coil temperature and outdoor coil temperature; or indoor coil refrigerant pressure and outdoor coil refrigerant pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

[0011] FIG. 1 provides a schematic illustration of a heat pump system according to one or more exemplary embodiments of the present disclosure.

[0012] FIG. 2 provides a flowchart illustrating an exemplary method of operating a heat pump system according to one or more additional exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[0013] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0014] As used herein, the terms includes and including are intended to be inclusive in a manner similar to the term comprising. Similarly, the term or is generally intended to be inclusive (i.e., A or B is intended to mean A or B or both). The terms upstream and downstream refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, upstream refers to the flow direction from which the fluid flows, and downstream refers to the flow direction to which the fluid flows.

[0015] As used herein, terms of approximation, such as generally, or about include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, generally vertical includes directions within ten degrees of vertical in any direction, e.g., clockwise or counterclockwise.

[0016] Turning now to the figures, FIG. 1 illustrates an exemplary heat pump system 100. The exemplary heat pump system 100 may be generally known as a split system or a multi-split system, e.g., the heat pump system 100 may include an outdoor portion 102, e.g., positioned outside of the structure to be cooled, and an indoor portion 104, e.g., positioned inside of the structure to be cooled. The outdoor portion 102 may include an outdoor unit 106, and the outdoor unit 106 may include an outdoor heat exchanger 108 and an outdoor fan 110. The indoor portion 104 may include at least one indoor unit 112, and the indoor unit 112 may include an indoor heat exchanger 114 and an indoor fan 116. In embodiments where multiple indoor units are provided, each indoor unit may be a substantial duplicate of every other indoor unit, e.g., each indoor unit may include a heat exchanger and a fan similar to those illustrated in FIG. 1. Accordingly, only a single indoor unit 112 is illustrated in FIG. 1 for the sake of clarity. The indoor unit 112 may be located in an enclosed space 180, such as a room, a mechanical closet, or other portion of the structure to be cooled.

[0017] Heat pump system 100 also includes a sealed system 130, e.g., generally comprising a series of conduits interlinking a compressor 118, the outdoor heat exchanger 108, the indoor heat exchanger 114 (as well as additional indoor heat exchangers of any other indoor units which may be provided), and other refrigerant flow components. Compressor 118 is operable to compress the refrigerant. Accordingly, the pressure and temperature of the refrigerant may be increased in compressor 118 such that the refrigerant becomes a more superheated vapor. The sealed system may be a thermodynamic assembly, which may be operated as a refrigeration assembly (and thus perform an air conditioning cycle or refrigeration cycle) or operated as a heat pump (and thus perform a heating cycle or heat pump cycle). Thus, as is understood, the exemplary heat pump system 100 may be selectively operated to perform a refrigeration cycle at certain instances (e.g., while in a cooling mode) and a heat pump cycle at other instances (e.g., while in a heating mode). The compressor 118 may be in fluid communication with the heat exchangers 108, 114 to flow refrigerant therethrough, as is generally understood. The outdoor and indoor heat exchangers 108, 114 may each include coils, through which the refrigerant may flow for heat exchange purposes, as is generally understood. Moreover, as may be seen in FIG. 1, heat exchangers 108, 114 may each include multiple circuits therethrough.

[0018] Operation of the heat pump system 100 in heating mode or cooling mode may be controlled or selected based on the position of a reversing valve 120, which may be, for example, a four-way valve. The reversing valve 120 selectively directs compressed refrigerant from compressor 118 to either indoor heat exchanger 114 or outdoor heat exchanger 108. The direction of refrigerant flow through the sealed system 130 in cooling mode is indicated by solid line arrows in FIG. 1, and the direction of refrigerant flow through the sealed system 130 in heating mode is indicated by dashed line arrows in FIG. 1. For example, in cooling mode, reversing valve 120 is arranged or configured to direct compressed, e.g., high-pressure, vapor refrigerant from compressor 118 to outdoor heat exchanger 108. Conversely, in heating mode, reversing valve 120 is arranged or configured to direct compressed, e.g., high-pressure, vapor refrigerant from compressor 118 to indoor heat exchanger 114. Thus, reversing valve 120 permits sealed system 130 to adjust between the heating mode and the cooling mode, as will be understood by those skilled in the art.

[0019] In cooling mode, the outdoor heat exchanger 108 acts as a condenser, e.g., outdoor heat exchanger 108 is operable to reject heat into the exterior atmosphere, when sealed system 130 is operating in the cooling mode. For example, the superheated vapor from compressor 118 may enter outdoor heat exchanger 108 from reversing valve 120. Within outdoor heat exchanger 108, the refrigerant transfers energy to the exterior atmosphere and condenses into a saturated liquid and/or liquid-vapor mixture. The exterior air handler or fan 110 positioned adjacent outdoor heat exchanger 108 may facilitate or urge a flow of air from the exterior atmosphere across outdoor heat exchanger 108 in order to facilitate heat transfer.

[0020] In cooling mode, indoor heat exchanger 114 acts as an evaporator. Thus, indoor heat exchanger 114 is operable to heat refrigerant within indoor heat exchanger 114 with energy from the indoor atmosphere when sealed system 130 is operating in the cooling mode. For example, the liquid or liquid-vapor mixture refrigerant may enter indoor heat exchanger 114. Within indoor heat exchanger 114, the refrigerant receives energy from the indoor atmosphere and vaporizes into superheated vapor and/or high quality vapor mixture. An indoor air handler or fan 116 positioned adjacent indoor heat exchanger 114 may facilitate or urge a flow of air from the indoor atmosphere across indoor heat exchanger 114 in order to facilitate heat transfer.

[0021] During operation of sealed system 130 in the heating mode, reversing valve 120 reverses the direction of refrigerant flow through sealed system 130. Thus, in the heating mode, indoor heat exchanger 114 is disposed downstream of compressor 118 and acts as a condenser, e.g., such that indoor heat exchanger 114 is operable to reject heat into the indoor atmosphere. In addition, outdoor heat exchanger 108 acts as an evaporator in the heating mode, e.g., such that outdoor heat exchanger 108 is operable to heat refrigerant within outdoor heat exchanger 108 with energy from the exterior atmosphere.

[0022] The heat pump system 100 may further include a gas service valve 122 and a liquid service valve 124. The heat pump system 100 may also include temperature sensors 166 at various locations throughout the system 100, e.g., to measure ambient temperatures, inlet temperatures, outlet temperatures, and/or temperatures of the heat exchanger coils, in various combinations based on the number and placement of the temperature sensors 166. The heat pump system 100 may further include an outdoor expansion valve 126 and a strainer 128. A high-pressure switch 140 may be provided on one side of the compressor 118 and a low-pressure switch 142 may be provided on the other side of the compressor 118. Furthermore, a capillary tube 144 and an oil separator 146 may be coupled to the compressor 118. The heat pump system 100 may further include an accumulator 150 configured to retain liquid-phase refrigerant therein and thus prevent liquid refrigerant flooding the compressor 118 (e.g., the liquid-phase refrigerant may accumulate within the accumulator 150 such that the liquid-phase refrigerant does not reach the compressor 118). A check valve 152 may be coupled to the accumulator 150 and may be positioned and configured to permit refrigerant flow to the accumulator 150 and prevent or limit refrigerant flow away from the accumulator 150.

[0023] An expansion device, e.g., electronic expansion valve 160, may be positioned indoors, e.g., in the indoor portion 104 of the heat pump system 100, downstream of the liquid service valve 124 and upstream of the indoor heat exchanger 114 when the heat pump system 100 is in cooling mode. When multiple indoor units 112 are provided, an expansion valve 160 may be provided for each indoor unit 114. The electronic expansion valve or valves 160 may generally expand the refrigerant, lowering the pressure and temperature thereof. The refrigerant may then be flowed through indoor heat exchanger 114. Additionally, the electronic expansion valve(s) 160 may be actuated, such as by a stepper motor, to selectively increase or reduce the flow rate of refrigerant therethrough. A strainer 162 may be provided between the electronic expansion valve 160 and the indoor heat exchanger 114.

[0024] As mentioned, the heat pump system 100 may be a multi-split system having one or more indoor units 112 in addition to the one illustrated example indoor unit 112. Refrigerant branches 164 extending to and from such additional indoor units are partially illustrated in FIG. 1 by way of example.

[0025] The operation of heat pump 100 including compressor 118 (and thus the sealed system 130 generally), indoor fan 116, outdoor fan 110, and other suitable components may be controlled by a control board or controller 158. Controller 158 may be in communication (via, for example, a suitable wired or wireless connection) with such components of the heat pump 100. Controller 158 may also be in communication with various sensors, e.g., temperature sensors 166, in the heat pump system 100. By way of example, the controller 158 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of heat pump system 100. The memory may be a separate component from the processor or may be included onboard within the processor. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller 158 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. Further, it should be understood that controllers 158 as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein.

[0026] It should be understood that the illustrated heat pump system 100 is generally referred to as a split system, and this configuration is provided by way of example only. The benefits of the present disclosure apply to other types and styles of heat pump systems as well. As one example, the heat pump system may also be provided as a one-unit type system, such as a single-package vertical unit (SPVU) or a package terminal air conditioner (PTAC), or any other suitable one-unit type air conditioner appliance, e.g., not limited to a SPVU or PTAC. As used herein, a one-unit type system generally includes a package housing that supports both an indoor portion and an outdoor portion within an interior of the single housing. Consequently, the description set forth herein is for illustrative purposes only and is not intended to be limiting in any aspect to a particular heat pump system configuration, e.g., the indoor portion and the outdoor portion may be portions of a single unit, e.g., may be provided in a single housing, or may include separate units, such as in the illustrated split system.

[0027] Turning now to FIG. 2, embodiments of the present disclosure may also include methods of operating a heat pump system, such as the example method 700 illustrated in FIG. 2. Such methods may be used with any suitable heat pump system, such as heat pump system 100 as described above, or any other heat pump system, e.g., any air conditioning unit or system, Heating Ventilation and Air Conditioning (HVAC) system, etc., which includes indoor and outdoor portions and a reversing valve such that the unit or system is operable in both cooling mode and heating mode in response to the position of the reversing valve.

[0028] For example, as mentioned above, the heat pump system 100 may include a controller 158 and the controller 158 may be operable for, e.g., configured for, performing some or all of the methods and/or steps thereof described herein. For example, one or more method steps may be embodied as an algorithm or program stored in a memory of the controller 158 and executed by the controller 158 in response to a user input.

[0029] As illustrated in FIG. 2, method 700 may include (710) obtaining a plurality of measurements from a plurality of sensors in the heat pump system. The plurality of measurements may include at least three measurements from at least three sensors (e.g., one reading or measurement from each of the three sensors in this example). The plurality of sensors may include one or more temperature sensors (e.g., temperature sensors 166) and/or other sensors such as refrigerant pressure sensors.

[0030] Method 700 may further include performing a plurality of status checks, such as (720) performing a first status check of the reversing valve by comparing a first set of sensor measurements and (730) performing a second status check of the reversing valve by comparing a second set of sensor measurements, e.g., where each status check of the two or more status checks comprises comparing a respective set of measurements from the plurality of measurements. Each set of measurements generally includes at least two measurements, e.g., a pair of measurements, from different sensors. As mentioned, the plurality of measurements from the plurality of sensors may include at least three measurements from three sensors, such that the first status check may include comparing two of the three measurements (e.g., the first set of measurements may be a first measurement from a first sensor and a second measurement from a second sensor) and the second status check may include comparing the third measurement with one of the other two measurements (e.g., the second set of measurements may include a third measurement from a third sensor and one of the first measurement or the second measurement). In additional embodiments, more than three measurements may be obtained from more than three sensors, such that each set of measurements includes completely unique measurements which are not in any other set of measurements, or combinations of both, e.g., some sets of measurements may have overlapping or common measurements while other sets of measurements in other status checks may be unique.

[0031] Method 700 may further include determining whether the reversing valve is in a fault condition based on the plurality of status checks, e.g., (740) determining whether the reversing valve is in a fault condition based on at least one of the first status check and the second status check. In some embodiments, the reversing valve may be determined to be in the fault condition based on all of the status checks, or less than all of the status checks. For example, methods according to the present disclosure may include validating sensor measurement values and basing the reversing valve status determination on only those status checks which include comparing valid measurements (e.g., status checks which include comparing sets of valid measurements, where each measurement in the set has been validated).

[0032] Determining whether the reversing valve is in the fault condition based on multiple status checks of the plurality of status checks may advantageously reduce the likelihood of a false positive (e.g., incorrectly determining that the reversing valve is in a fault condition when it is not) and may provide greater fidelity across a larger range of operating conditions. For example, some sensors may be more accurate in heating mode than in cooling mode (or vice versa), such that determining whether the reversing valve is in the fault condition based on multiple status checks that incorporate a variety of measurements from different sensors at different locations in the heat pump system may provide greater fidelity across a wider range of operating temperatures and refrigerant pressures, e.g., in both heating mode and cooling mode.

[0033] In general, it is to be understood that methods according to the present subject matter include operating the heat pump system and are performed, e.g., measurements are obtained, while the heat pump system is operating. Thus, determining whether the reversing valve is in the fault condition is to be understood as checking that the heat pump system is operating as intended, e.g., in heating mode when heating is called for or in cooling mode when cooling is called for. The call for heating or cooling may come from a thermostat of the heat pump system, e.g., which measures a current ambient temperature within the conditioned space and compares the current ambient temperature within the conditioned space to a target temperature or range of target temperatures. When the current ambient temperature within the conditioned space is greater than the target temperature or above the upper limit of the target temperature range, the thermostat calls for cooling, and when the current ambient temperature within the conditioned space is less than the target temperature or below the lower limit of the target temperature range, the thermostat calls for heating. The call for heating or cooling may also or instead come from a user interface or user input, e.g., which receives a selection from a user for cooling mode or heating mode.

[0034] When there is a call for heating or cooling, the heat pump system may activate, e.g., by moving the reversing valve to the appropriate position for the selected mode (or at least attempting to do so) and starting the compressor to begin the flow of refrigerant through the sealed system. In some embodiments, methods according to the present disclosure may include waiting for the heat pump system to stabilize, e.g., to reach a steady state of operation, before obtaining the plurality of sensor measurements. The obtained plurality of sensor measurements may then be validated, and each valid status check (e.g., those status checks for which all measurements, e.g., both measurements, in the respective set of measurements passed the validation check) may be performed, and the reversing valve fault condition may be determined based on all of the performed status checks or a majority of the performed status checks. For example, to minimize or avoid false positives, a reversing valve fault condition may, in some embodiments, be determined only when all of the valid status checks indicate the reversing valve is in the fault condition.

[0035] The fault condition may indicate that the reversing valve is, e.g., stuck, damaged (such as wiring to actuate the reversing valve may be damaged), that a relay between the controller and the reversing valve may be broken, and/or other reversing valve faults may be present which result in operating the heat pump system in the wrong mode (heating when it should be cooling or vice versa).

[0036] Validating the sensor measurements may include determining whether each sensor measurement is within a generally expected operating range. For example, very high or very low temperature readings from a temperature sensor may indicate the temperature sensor is providing invalid readings.

[0037] In some embodiments, the first set of sensor measurements (e.g., which are compared in the first status check at 720) may be obtained from a first temperature sensor and a second temperature sensor, and the second set of sensor measurements (e.g., which are compared in the second status check at 730) may be obtained from the first temperature sensor and a third temperature sensor. In additional embodiments, the first set of sensor measurements (e.g., which are compared in the first status check at 720) may be obtained from a first temperature sensor and a second temperature sensor, and the second set of sensor measurements (e.g., which are compared in the second status check at 730) may be obtained from a third temperature sensor and a fourth temperature sensor.

[0038] In some embodiments, as mentioned above, (740) determining whether the reversing valve is in the fault condition may include determining the reversing valve is in the fault condition based on all of the status checks, e.g., on both of the first status check (from 720) and the second status check (from 730), or from more than two status checks in additional embodiments.

[0039] As mentioned, the fault condition of the reversing valve may be determined based on a majority of the status checks. For example, in some embodiments where the first status check returns a fault status and the second status check returns a normal status, exemplary methods such as method 700 may further include performing a third status check by comparing a third set of sensor measurements. When the third status check returns a fault status, determining whether the reversing valve is in the fault condition may include determining the reversing valve is in the fault condition based on the first status check and the third status check. When the third status check returns a normal status, determining whether the reversing valve is in the fault condition may include determining the reversing valve is not in the fault condition based on the second status check and the third status check.

[0040] The heat pump system may also include a user interface, such as a display and one or more user input devices. In some embodiments, the user interface, e.g., the display thereof, may be configured for, and exemplary methods may include, providing a user notification in response to the detected reversing valve fault. The user notification may be or may include a visual notification, e.g., on the display, an audible notification, e.g., a beep, chime, or other alert sound, or combinations of audible and visual notifications. The user notification may be provided locally, e.g., on a user interface of the heat pump system 100 that is onboard the heat pump system, e.g., directly physically integrated into the heat pump system, and/or may be provided remotely, e.g., on a remote user interface such as a computer (e.g., personal computer or tablet computer), smartphone, or other similar device which is spaced apart from the heat pump system 100 and in wireless communication with the heat pump system 100, e.g., with the controller 158 thereof.

[0041] In additional embodiments, any suitable number of status checks and sets of measurements may be used, e.g., more than two status checks comparing more than three total measurements (in addition to the first and second status checks and the at least three measurements from at least three sensors described above). For example, the sets of sensor measurements which are compared in the multiple status checks may include any or all of the following sets: indoor air outlet temperature and indoor air inlet temperature; indoor coil temperature and indoor air inlet temperature; outdoor coil temperature and outdoor air inlet temperature; indoor coil refrigerant pressure and indoor air inlet temperature; outdoor coil refrigerant pressure and outdoor air inlet temperature; indoor coil temperature and outdoor coil temperature; and/or indoor coil refrigerant pressure and outdoor coil refrigerant pressure.

[0042] In one exemplary status check, a coil temperature may be compared with a corresponding inlet temperature, such as the outdoor coil temperature may be compared with an outdoor inlet temperature measured at an inlet into the outdoor unit and/or outdoor portion. In this example, when the outdoor coil temperature and the outdoor inlet temperature are within a certain range of each other, e.g., are relatively close, such as plus or minus 3 Fahrenheit of each other, the status check may be inconclusive. When the outdoor coil temperature is below the outdoor inlet temperature (and, e.g., outside of the inconclusive range, such as less than the outdoor inlet temperature by at least 3 Fahrenheit), the outdoor coil may be determined to be operating as the evaporator, e.g., which would indicate the reversing valve condition is normal when in heating mode or the reversing valve is in a fault condition when cooling is called for. When the outdoor coil temperature is greater than the outdoor inlet temperature (and, e.g., outside of the inconclusive range, such as above the outdoor inlet temperature by at least 3 Fahrenheit), the outdoor coil may be determined to be operating as the condenser, e.g., which would indicate normal reversing valve condition when cooling is called for or the reversing valve is in a fault condition when heating is called for.

[0043] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.