[alfredwhite1]

I have a Heil central air, heat pump unit. I am having periodic trouble with the compressor running while the blower is not. I can turn the breaker off for about 30 minutes and restart the unit and it does fine. Weird thing is, even turning off the thermostat will not turn the compressor off while it is going through one of these spells. Can anybody please tell me what is going on??

[hvac1000]

It seems my first thought is that the contactor in the outside unit might be sticking SOMETIMES. The reason I say this is that the contactor controls the outside units main power. It is activated by low voltage coil system and if the low voltage is not present as when the thermostat is not calling for the outside unit to perform then the only way for the outside unit to be on is if the contactor is stuck closed. So the contactor is the first item I would check.

While you are outside checking this item look around at your low voltage cable that feeds the unit. It is a small wire with many other wires inside. Many times it can be chewed on by a dog or other small animal and this can cause the contactor to activate under some conditions.

The contactor will look something like these and TURN off the power first before inspecting it. The contacts could be worn OR pitted and that can and will cause it to stick. Report back with your findings. NOTE: contactor located behind access panel on outside unit. Remember to turn off main 220/240 volt power first. You do not need to be turned into a chrispy critter on my watch.

[hkstroud]

Assuming that by blower you mean condenser fan, sounds like a faulty contacter to me. A faulty contacter with sticking contact points but then I am not a AC mechanic.

[alfredwhite1]

Thanks hvac 1000, found the contactor. It is like the large one shown in the picture. Low voltage cable appears to be fine. The contactor is so that I can't really get a good look at the contacts, but the little tab that sticks out seems like the springs that hold it are very weak. Is there a way to check the contacts without take the contactor apart? Again THANKS

[hvac1000]

They can be hard to see. Usually they might have black or dark makings if defective. The sprihgs do not have much strength since they only open a light weight set of contacts. What you could do is wait till the unit is not working properly and then look to see if the contacts are closed. If closed then you can take a voltage measurement across the 24 volt contacts to see if voltage present if voltsge not present and the contacts are closed then they are stuck.

Intermittent problems are the most difficult to find.

BTW the large one in the picture only has one set of contacts not two. It is a bypass style contactor that allows 120 volts to always bleed through to keep the crank case heat ot compressor windings active for cool weather operation and to keep the oil warm and liquid refrigerant out of the crank case area.

[alfredwhite1]

Thanks for the help. Contactor was bad, points burned badly. I replaced contactor and the unit is working fine. It is nice to know that in a world where so many people charge for so many things that good advice can still be FREE. Thanks again so much, Al White

[hvac1000]

Glad you got it going.