AC Incident 01/11/2022: Main Floor AC Outdoor Unit not Working

* Outdoor temp: 22 F
* Thermostat setting: 69 F
* Changes:
– changed to wifi Honeywell RTH6580WF

* Main outdoor unit not Working
– condenser not working, no humming
– condenser fan not working, no kicks

* Set thermostat to heat mode

* Revert back to old thermostat didn’t help
==> Not due to new wifi thermostat

* Furnace/fan works
* Auxiliary heat works
* Emergency heat works
==> Indoor unit ok

* Condenser no activity, no humming
* Conderser fan not spnning, no kicks
* System board (System operation monitor diagnostics):
– power/green light: on => power on
– alert/yellow light: flashes 5 times => open circuit (observed once in the morning)
– trip/red light: on => system and compressor system check ok
==> Open circuit
* Defrost board:
– Green light: slow sync flashing
– Red light: slow sync flashing
==> normal
* Ref:

Lennox error codes

https://www.fixya.com/support/t26979898-nothing_coming_when_tried_turn_ac_or

* Appearance looks good
* Capacitor measures good
– herm to C: 70 uf
– fan to C: 10 uf
* Capacitor wiring:
– purple line to fan
– red line to C (commond)
– yellow line to Herm (condenser)
* Change to new capacitor did not help
==> Capacitor ok

* Thermostat voltages:
R2C: 27v
Y2C: 27v
O2C: 27v
==> thermostat demand looks good
* Sensor voltages:
– low pressure: ok (forgot number)
– high pressure: ok(forgot number)
* Manual reset defrost board
– turn off high voltage
– remove and reattach R terminal
– wait for 5 min
– turn on high voltage
– Still not working
==> probably not due to defrost board since it can be manually reset
* Ref:
– General




– Low pressure switch:

– High pressure swith:

* Contactor is being pulled in when there is voltage demand from thermostat
==> Contactor probably good
==> Defrost board probably good
* Voltages:
– main in to ground:
red: 110v
black: 110v # this probably due to contactor being pulled in to complete the circuit
– main out to ground:
red: 110v
black: 110v # this probably due to contactor being pulled in to complete the circuit
– main red to main black: 0v !!!
* Ref:

* Outdoor blade switch voltages:
– Main in to ground:
red: 110v
black: 0v !!!
– Main in red to black: 110v
==> One leg of main power, i.e. black leg, open!!!
* Panel volages:
– 45A circuit breaker read: 110v
– 45A circuit breaker black: 0v !!!
==> Bad circuit breaker
* Ref:
– Power bad:

Compressor and fan don’t start. Solenoid kicks in though. Where to start?
byu/mcveigh0352 inHVAC

https://www.fixya.com/support/t26979898-nothing_coming_when_tried_turn_ac_or

* Change outdoor heatpump unit panel breaker (45A)
– couldn’t find 45A so replaced with 40A circuit breaker