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.
Possible Causes (From Most to Least Likely): |
Qty |
Bad Blower Motor |
1 |
Bad Capacitor |
|
Bad Breaker |
1 |
Blown Low Voltage Fuse |
|
Bad Heater Sequencer(s) |
1 |
Bad Control Board |
|
Bad Limit Switch |
|
Bad Heaters |
|
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.
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
- 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