What could be causing the delay in the start up of the air conditioner


I have an air conditioner that is probably 15 years old now. The problem is when I turn it on after it has been off for a long period of time (several hours) it takes a long time for the outdoor unit (compressor?) to start running.

The outdoor unit has a large fan in the middle with cooling coils around the perimeter and cooling fins. It had been running just fine up until three summers ago. Two winters ago, my heater went out and I had it replaced. The following summer (last summer) I went to turn on the air conditioner for the first time and it took so long (30 minutes) to come on that I thought it was broken or not wired up or a fuse blew. I checked all the obvious things like the set temp was below the room temp. (72 < 90). The wall unit has a red light that glows when either the heater or air conditioner unit is operating. I figured the heating & cooling guys forgot to hook something up. Having a bit of electrical know-how, I went and checked the outside fuses and other things and could see the outdoor unit had voltage going to the outdoor unit.

Just today, first time turning on the air conditioner for the year and same behavior. Here is the interesting thing though. Once the unit kicks on, it cycles normally. I can hear a small click (relay closing) on the inside thermostat unit each time the termostat cycles on/off. I can then hear the outside unit kick on within a few seconds of hearing that click (normal).

On mild days, I turn the air conditioner off and it may be off for a day or two but then turning it on for the first time, I can hear the thermostat click but the outdoor unit takes 30 minutes on average to come on for the first time.

I don't have a schematic for the unit but I can't imagine an outdoor relay taking that long to engage if it's a relay problem. Also the outdoor unit has this blanket around the motor. I tried removing it when this problem first began but the unit seems sealed up.

The guys that put in my new furnace insist they did nothing that would have caused this but want $85 to come look at it.

Anyone recognize this behavior?

Best Answer

There is probably an old capacitor in the electronics which dried out over the time and now takes a long time to gain the necessary power load. If you are familiar with electronics you can check yourself for capacitors which looks bloated or otherwise funny and replace them.