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JPGREEN · Jan 18, 2007, 02:23 PM

I have a single package air conditioner. I have wired up the unit and the cooling system works fine, but the heating is confusing me. The heater coils are working but the control circuit or thermosat is not right. When you turn the heat on the fan starts and you can feel the heat. After about 60 secs. The air becomes cold. About 60 secs. Later it is hot. It does this over and over. The only thing that I can imagine is that I have the thermostat wiring wrong. Can anyone help me out?

Thanks,

JPGREEN

labman · Jan 18, 2007, 02:38 PM

I doubt the thermostat is the problem. Usually they switch the control power to heat, and leave it until the rising temperature opens the switch. If it is a simple stem, you can jumper the R and W terminals at the furnace. That bypasses the thermostat. Unless that fixes the problem, the thermostat is OK.

Is this a A/C with electrical resistance heat or a heat pump? Sounds more like a bad temperature sensor. It signals the system is overheated, it shuts the heat off, it cools off, and it turns the heat back on, etc. You need to identify the heat sensor, and clean or replace it. It may be labeled High limit switch on the schematic.

NorthernHeat · Jan 18, 2007, 03:45 PM

Furnace has insufficient air flow is is not properly sized, a limit switch is turning off the heat until it cools down then it starts all over again.

T-Top · Jan 18, 2007, 07:43 PM

With some of the electric heating systems you have to have a G call from the thermostat with the W call. G being the green wire (blower) and W being the white wire (heat). At the turn the fan switch to on so the blower will run then turn the heat-cool switch to heat and move the temp up if it heats and keeps running you need a thermostat that calls for the blower in heat or cool.

SteveMac · Feb 1, 2007, 09:21 AM

I Have just recently developed a problem with my heating. When I turn on the heat there is a loud buzzing noise. After about 10 secs the motor seems to kick in and send air streaming out of the vents. The air seems to be flying out a lot more rapidly then before the problem developed. After about 4 min of bursting air out of the vents it stops. The fan located on a outdoor unit continues to spin however inside noting is happening. The air that bursts out seems to be un heated. After the first 4 min burst the unit turns off. Leaving the home un heated. Does anyone have a idea on what could be causing this problem. If so how much should I expect to pay for having it fixed. Thanks.