Coleman Heat Pump: FRHS

Re: Outdoor Unit Not Running

The indoor blower is operating, but the outdoor unit fan and compressor are not running.

► This unit has a Current-Sensing Lockout Relay. If the CSR receives a call for "Y" and sees no compressor amperage, it enters lockout mode and powers the "L" terminal on the LTB. 

CHECKOUT:

1. Check High Voltage Power & Contactor

• Check for 230VAC inlet power across L1 and L2 of the compressor contactor.
  • No Power ⇒ Check Disconnect and Breakers
    • Check for a "Short-to-Ground" before checking/resetting the breaker!
• Check to see if the compressor contactor is pulled-in.
  • Not Pulled-In → Step 2. Check Low Voltage
  • Pulled-In + Inlet Power + Not Running = Bad Contactor or Bad Capacitor ⇒ Check for 230VAC on the leaving side of the contactor.
    • Power In + No Power Out = Bad Contactor
    • Power Out + Not Running ⇒ Check for a Bad Capacitor, Locked-Up Compressor or Burnt Wires to Compressor
      • Motor and Compressor could both be off on over-temperature

2. Check Low Voltage Power

• Ensure the thermostat is calling for either heating or cooling.
• At the outdoor LTB, check for 24VAC between "B" and "X".
  • No Power = Bad Transformer or Incorrect Wiring
• Check for 24VAC between "Y" and "X" at the LTB.
  • No Power = No Call from the Thermostat ⇒ Recheck Stat
    • Look for a Condensate Overflow Switch at the air handler.
• Check for 24VAC at the compressor contactor coil.
  • 24V Power+ Not Pulled-In = Bad Contactor
  • Power on "Y" + No Power at Contactor = Current Sensor Lockout or Bad Safety ⇒ Check Safety Circuit

3. Check Safety Circuit

• Time Delay Relay
• Check for 24VAC Inlet Power between E3 & E4.
  • No Power = No call for "Y" or Broken Common Wire (X).
• Check for 24VAC Outlet Power between E1 & E2
  • Inlet Power + No Outlet Power = Bad Time Delay or Waiting
• Current Sensor
• Check for 24VAC Inlet Power between Terminal 1 & 2.
  • No Power = Bad Defrost Relay #1
• Check for 24VAC Outlet Power between Terminal 1 & 3.
  • Inlet Power + No Outlet Power = Tripped Current Sensor ⇒ Confirm by checking for 24VAC between Terminal 1 & X on the Current Sensor or "L" to "X" on the LTB.
    • Power Present = Locked-Out ⇒ Check High Pressure & High Temp Switch
• High Pressure/Temperature
• Check continuity across each safety

4. Check Refrigerant Charge

• Hook-up refrigerant gauges to the unit.
• Reset the control by cycling power to "Y".
• Observe the pressures as the system operates.
  • High Pressure Switch should open above 450 psig.