Why is my supplemental heat light on when the A/C is running. I can feel warm air coming from a couple of vents. Can the heat pump be disconnected for the time being or does it run with the A/C as well

Thanks, Rainey

The heat pump must run for both heating and cooling. The supplemental heat should only run in the coldest weather when the heat pump can't extract enough heat form outside to keep the house warm enough. It sounds to me like a relay or a thermostat is stuck and the system is working against itself, the heat pump cooling, and the supplemental elements heating. The unit itself may have a schematic inside a cover or something, or you may have a book with one. If you can't follow one and check to see what is happening, you need to call a qualified service man. In the meantime, you could shut off any breaker labeled as supplemental heat.

This needs prompt attention. A lack of cooling is just the beginning. It will be drawing very high power resulting in a large bill. It may overwork itself and fail, leading to another huge bill.

In rereading your question, if the air conditioner and heat pump are separate systems, the whole problem may be solved by shutting the heat pump off.

My original answer was for the common system where the heat pump does all the heating and cooling.

Yes I have a big unit in my attic and a small unit outside, which I am thinking is the heat pump. The light is very dim, but I think the strips are coming on. I was'nt sure if I could turn the disconnect off to the outside unit, because I didn't know if it served anything during the cooling prosess. Thanks, Rainey

There is definitely a fan outside which must run, heating or cooling. You must leave the main outside disconnect on. I am not sure where the compressor or heating strips are. If you can disconnect the heating strips, you can run the unit until the problem is fixed.