York Heat Pump: THGD

Re: Outdoor Unit Running Continuous/Over-Heating

The customer reports that the indoor and outdoor unit are running continuous and overheating the space.

CHECKOUT:

1. Check Outdoor Unit

• Outdoor Running → Step 2. Check Contactor
• Outdoor Not Running ⇒ Remove the outdoor unit access panel & check for 240VAC at the contact Inlet Power
  • Power Present → Step 3. Check Air Handler
  • No Power ⇒ Check Disconnect & Breaker ⇒ Check with the customer to see if they turned something off.

2. Check Contactor

• Remove the access panel of the outdoor unit.
• Check for 24VAC between "Y" and "C".
  • Power Present → Step 3. Check Thermostat
  • No Power + Unit Running = Stuck Contactor

3. Check Air Handler

• Blower Not Running → Step 4. Check Thermostat
• Blower Running ⇒ Check for 24VAC between ["W1" and "C"], ["W2" and "C"], ["G" and "C"]
  • Power Present → Step 4. Check Thermostat
  • No Power + Blower Running ⇒ Check for any active fault codes on the control board.
    • Code 2 indicates multiple limit openings with NO CALL FOR HEAT ⇒ Check for a Stuck Contactor or Stuck Heat Relay(s).
    • Code 3 indicates multiple limit openings during a call for heat. (Fan runs continuous until power is cycled.)

4. Check Thermostat

• At the thermostat, compare the Space Temperature to the Heat Setpoint.
  • Space Temp > Setpoint + Call For Heat = Bad Thermostat
  • Space Temp < Actual Temperature ⇒ Check for Cold Air Behind Thermostat
  • No Call for Heat + System Operating ⇒ Remove Thermostat from sub-base and re-check for 24VAC between "Y" and "C" at outdoor unit.
    • Power Goes Away = Bad Thermostat
    • Power Still Present = Shorted Control Wire