Alternative defrost mode of HVAC system

1. A heating, ventilation, and air conditioning (HVAC) system, comprising:

a first sensor configured to determine a first temperature;

a plurality of second sensors, wherein the plurality of second sensors is configured to determine a plurality of second temperature values; and

a controller communicatively coupled to the first sensor and to the plurality of second sensors, wherein the controller is configured to:

operate the HVAC system to defrost a coil of the HVAC system based on the first temperature in response to determining that feedback indicative of the first temperature is available from the first sensor; and

in response to determining that the feedback indicative of the first temperature is unavailable from the first sensor, select a second temperature value of the plurality of second temperature values based on a priority scheme and operate the HVAC system to defrost the coil based on the second temperature value.

2. The HVAC system of claim 1 , wherein the controller comprises a control board, the first sensor comprises an outdoor ambient temperature sensor, and the plurality of second sensors comprises a sensing circuit integrated with the control board.

3. The HVAC system of claim 1 , wherein the first sensor comprises an outdoor ambient temperature sensor, the first temperature comprises an outdoor ambient temperature, the plurality of second sensors comprises a thermostat coupled to a network and configured to determine an ambient temperature at a geographic location of the HVAC system via the network, and the second temperature value comprises the ambient temperature at the geographic location of the HVAC system.

4. The HVAC system of claim 1 , wherein the first temperature comprises an outdoor ambient temperature, and the second temperature value comprises a coil temperature of the coil.

5. The HVAC system of claim 4 , wherein the controller is configured to:

determine whether the coil temperature has been below a threshold temperature for a threshold time period; and

execute a pre-set defrost cycle to defrost the coil in response to determining that the coil temperature has been below the threshold temperature for the threshold time period.

6. The HVAC system of claim 1 , wherein the first temperature comprises a coil temperature of the coil, and the second temperature value comprises an outdoor ambient temperature.

7. The HVAC system of claim 6 , wherein the controller is configured to:

determine whether the outdoor ambient temperature has been below a threshold temperature for a threshold time period; and

execute a pre-set defrost cycle to defrost the coil in response to determining that the outdoor ambient temperature has been below the threshold temperature for the threshold time period.

8. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, are configured to cause the one or more processors to:

operate a heating, ventilation, and air conditioning (HVAC) system to defrost a coil of the HVAC system based on a first temperature measurement in response to determining the first temperature measurement is available;

determine the first temperature measurement is unavailable; and

in response to determining the first temperature measurement is unavailable, select an alternative temperature measurement from a plurality of alternative temperature measurements based on a priority scheme and operate the HVAC system to defrost the coil based on the alternative temperature measurement.

9. The non-transitory computer-readable medium of claim 8 , wherein the instructions, when executed by the one or more processors, are configured to cause the one or more processors to:

receive the first temperature measurement via feedback from a sensor of the HVAC system; and

determine the first temperature measurement is unavailable based on the feedback from the sensor being unavailable.

10. The non-transitory computer-readable medium of claim 9 , wherein the sensor is a first sensor, and the instructions, when executed by the one or more processors, are configured to cause the one or more processors to receive the plurality of alternative temperature measurements from a plurality of additional sensors of the HVAC system.

11. The non-transitory computer-readable medium of claim 10 , wherein the instructions, when executed by the one or more processors, are configured to cause the one or more processors to:

adjust the alternative temperature measurement to provide an adjusted temperature value; and

operate the HVAC system to defrost the coil based on the adjusted temperature value.

12. The non-transitory computer-readable medium of claim 8 , wherein the instructions, when executed by the one or more processors, are configured to cause the one or more processors to:

determine a total resistance value of a plurality of resistors based on a respective resistance value of each resistor of the plurality of resistors;

reference data correlating the total resistance value with a temperature value; and

determine the first temperature measurement based on the temperature value.

13. The non-transitory computer-readable medium of claim 12 , wherein the instructions, when executed by the one or more processors, are configured to cause the one or more processors to:

determine a particular resistance value of one of the plurality of resistors is unavailable;

determine a new total resistance value of the plurality of resistors based on the respective resistance values of remaining available resistors of the plurality of resistors;

reference alternative data correlating the new total resistance value with an updated temperature value; and

determine the first temperature measurement based on the updated temperature value.

14. The non-transitory computer-readable medium of claim 8 , wherein the instructions, when executed by the one or more processors, are configured to cause the one or more processors to:

determine whether the alternative temperature measurement has been below a threshold temperature for a threshold time period in response to determining the first temperature measurement is unavailable; and

execute a pre-set defrost cycle to defrost the coil in response to determining that the alternative temperature measurement has been below the threshold temperature for the threshold time period.

15. A heat pump system, comprising:

an outdoor coil; and

a controller configured to:

receive first feedback from a first sensor;

receive second feedback from a plurality of additional sensors, wherein the second feedback comprises a plurality of alternative measurements;

operate the heat pump system to defrost the outdoor coil based on the first feedback in response to receiving the first feedback from the first sensor;

determine that the first feedback is unavailable; and

in response to determining that the first feedback is unavailable, select an alternative measurement of the plurality of alternative measurements based on a priority scheme and operate the heat pump system to defrost the outdoor coil based on the alternative measurement.

16. The heat pump system of claim 15 , wherein the first feedback is indicative of a first temperature measurement, and at least one of the plurality of alternative measurements of the second feedback is indicative of a second temperature measurement.

17. The heat pump system of claim 16 , wherein the controller is configured to determine the first feedback is unavailable in response to determining the first feedback is not received by the controller or in response to determining the first temperature measurement exceeds a threshold temperature.

18. The heat pump system of claim 16 , wherein the first temperature measurement comprises a temperature of the outdoor coil, and the at least one of the plurality of alternative measurements comprises an outdoor ambient temperature.

19. The heat pump system of claim 15 , comprising a fan, wherein the controller is configured to operate the fan at full capacity to defrost the outdoor coil based on the alternative measurement.

20. The heat pump system of claim 15 , wherein the controller is configured to:

determine the second feedback is unavailable;

determine an operating mode of the heat pump system in response to determining the first feedback is unavailable and the second feedback is unavailable; and

suspend operation of the heat pump system in response to determining that the operating mode of the heat pump system is a heating mode.