Heat Pump - No Heat

Heat Pump

Re: No Heat

When a customer reports "No Heat' with a heat pump, that generally indicates a problem with the indoor blower or electric heaters.

► There may be a problem with the heat pump itself, but the auxiliary heaters should cycle on to keep the temperature within 1 degree of the Heat Setpoint.

CHECKOUT:

1. Check Operation

• Make sure the thermostat is set correctly and calling for Heat.
• Check to see if sufficient air flow is coming from the supply registers.
  • No Airflow --> Step 2. Check Line Voltage Power
  • Airflow --> Step 3. Check Low Voltage Power

2. Check Line Voltage Power

• Turn off power to the air handler.
  • If present, turn off the air handler breakers.
• Remove access panel.
• Look for any signs of burnt wires or controls.
• If air handler breakers present, check for 230V inlet power to breakers.
  • No Power --> Check breaker box
• Turn air handlers breakers back on.
• Check for 230V outlet power at breakers.
  • Inlet power but no (or low) outlet power = Bad Breaker

3. Check Low Voltage Power

• Check for 24VAC between "R" and "C" on the air handler low voltage wiring.
  • No Power = Blown Low Voltage Fuse or Bad Transformer
• Check for 24VAC between "G" and "C" on the air handler low voltage wiring.
  • Power Present = Indoor Fan Should Be Running
    • No Fan --> Step 4. Check Blower Motor and Capacitor
• Check for 24VAC between "W" and "C" on the air handler low voltage wiring.
  • No Power = No call for Aux Heat from the thermostat or Mis-Wiring
  • Power Present + Blower Running --> Step 5. Check Heaters

4. Check Blower Motor & Capacitor

• Check Capacitor
  • Turn off power to the air handler.
  • Remove capacitor wires (short before touching)
  • Move Multi-Meter leads to COM and MFD.
  • Set Meter to 200 MFD.
  • Place one lead on each side of the capacitor. 
  • Confirm MFD reading with capacitor rating.
    • Less than 80% of rating = Bad Capacitor
  • SWITCH METER LEADS BACK TO COM AND V BEFORE PROCEEDING!
• Check Blower Motor
  • Check for 230V across blower motor "COM" and the Speed wire.
    • Power but No Motor Operation = Bad Blower Motor
    • No Power = Bad Fan Control

5. Check Heaters

• Amperage
  • With a call for "W" (or W1 and W2) use an Amp Probe to check amperage of each heater.
    • No amperage = Bad Heater Controller, Bad Limit or Bad Heaters
• Voltage
  • If accessible, check for 230V across each heater.
    • No Voltage = Bad Heater Controller(s) or Bad Limit(s)
    • Voltage but No Amperage = Bad Heater