I am the proud owner of a 10+ year old Heil split system (heat pump w/ propane furnace). I noticed it was not heating correctly, and went outside when it was calling for heat pump operation and the heat pump was not running. I noticed a slight burning odor. I shut off the disconnect, and set the system to operate on gas heat only. That was a couple of weeks ago, and today is the first chance I've had to go nose around.

When the thermostsat calls for heat pump heat, the contactor pulls in and I'm getting 220V going to the compressor. The compressor, however, simply makes a 1/2-1 second buzzing sound every 15-20 seconds. Is that an indication that the compressor is shot, or is the capacitor not kicking hard enough, or might it be something else?

For kicks and giggles, I set the thermostat for air conditioning to see what would happen, and the buzz every 15-20 seconds was the same, except the compressor hummed for the duration of the testing process. There was silence between the buzzes when set for heat.

The compressor has two leads coming from the contactor and one smaller lead coming from the capacitor. Is there a test I can do on those leads (on the wiring compartment end) to determine what might be the problem?

 

One more thing - the compressor fan doesn't come on. When is it supposed to come on - at the same time as the compressor? Before? After?

 

If the fan and the compressor dont run then you must have a break in a wire or a bad contactor. It also could be the run capacitor. Either way, leaving the power on could harm the compressor. It may have already. Check to see if the compressor and fan share a run capacitor. Other than that, you need to call for service. Oh, and the continuous humm while in a/c mode is the reversing valve not the compressor. Good luck.

 

The contactor pulls in and sends 230V to the compressor. I have verified the voltage on the load side of the contactor, but not at the compressor itself because it's at the bottom of the unit and I can't get to the wiring compartment on the side of the compressor. It does make that strange cyclical buzzing sound when the contactor is pulled in.

How do you test a capacitor? When I noticed that smell, it seemed to be coming from the wiring compartment.

Is there a standard sequence between the compressor motor and compressor fan? Do they both start at the same time or is there a delay on one?

 

With a capacitor tester or look for oil around them. look and see if they look blowed out or puffed up .Then they are bad. From what you say you have to go down in the compressor and check the wires on it and then ring it out also to see if it is bad. That 15 to 20 sec buzz Id say its riding the klixon on the compressor. Something is not right there. I dont tthink that old of heatpump would have a fan cut off in it and the fan should run when the compressor does

ED

 

I'll look at the capacitor again, but visually it looked fine. The compressor only has 3 wires - 230V phase wires and a smaller wire for the capacitor winding. I don't know how I would get to the wires to take readings at the compressor - the wiring "compartment" is on the side of the compressor at the bottom of the unit. I took the cover off the compartment, and from my angle it's hard to see how they're hooked up.

When I ohm out the wires, what am I supposed to find if the compressor is bad? Open between phases?

 

It was the capacitor. It was a dual capacitor that boosted the compressor and the fan. It read open between the common and each of the other two terminals.