Heat Pump
No Heat and/or AC

Heat Pump Not Running


Is thermostat calling for heat?

If not:

Raise thermostat to activate call.


Is blower running?

(Blower should always be running on a call for heat.)

If Blower Not Running:

Check circuit breaker at panel and at unit.

Check control fuse in air handler.

Turn power off to air handler.

Spin blower wheel.  Is it seized?

If yes:  Condemn motor.

If not:  Check capacitor.

If bad:  Replace.

If ok:  Turn power back on.

             Is there voltage to motor?

If yes:  Condemn motor.

If Blower Is Running:

Is outdoor heat pump running?

If not:

   Check circuit breaker at panel.

   Check if outdoor disconnect is on.

   Open control panel.

   Is there 230 volts at contactor?

If not:  Find tripped breaker.

If yes:  Is there 24v at contactor coil?   

If yes:  Is contactor pulled in?

If Contactor Not Pulled In:

Replace contactor.

If No 24v At Coil But There Is

24v At Wire Nuts:

   Check charge.

   Unit may be off due to low pressure or

   high pressure safety.  Check LP switch.

If open:  Check charge.  Check HP Switch.

If open:  Check coil for dirt.  Check fan motor.

If not running:  Check power to motor.

If power is there:  Condemn motor.


If Contactor IS Pulled In:

Is there 230 volts at load side of contactor?

If not:  Replace contactor.

If yes:  Check capacitors.

If capacitor is bad:  Replace.

If capacitor is good, and contactor is pulled in, and there is 230 Volts present at load side:

Both compressor and fan should be running.

If  the fan is running but the compressor is not:

feel the compressor to see if it is hot. 

If hot:  Compressor may be off on overload.

If so:  Ohming the leads will show an open circuit between common and start.

If overload is activated:  nothing more can be done until overload resets.  May take up to 3 hours to reset.



If Heat Pump Is Running:


What is Delta T in Heat Mode?

Below  15:  Check and add charge.  Use charts inside unit.

Are electric heaters being called for (2nd Stage Heat):

If yes:  Amp heater to make sure they are operating.

If no:  Is 2nd stage being called for?

If yes:  Heaters may be bad.


What is Delta T in Cool Mode? 

Should be between 17 - 25 degrees.

If less than 17 degrees:  Check charge.  Use charts inside unit.  Use sub-cooling.

If more than 25 degrees:  Check filters for dirt.  Check for lack of air flow.