Air Conditioning - problem: compressor tied to inside blower
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swanie23
04-25-09, 08:51 AM
Hello, I think I have a problem with the way my HVAC is set up. Whenever I use the thermostat to turn the fan mode to ON, my AC unit outside always kicks on. This happens even if the mode is set to HEAT, COOL, or OFF. I thought the compressor should only kick on if the mode is COOL and the interior temp is above the threshold? Is something miswired? It has worked this way ever since I bought the house. I'd like to be able to run the blower to circulate the air in the house without the AC kicking on. Thanks
ecman51`
04-25-09, 12:05 PM
Miswired or shorted between in such a way that connections Y and G cannot be separated, as is.
Do you have newer style programmable stat? If so, someone probably changed it and miswired something and/or did not maybe pay attention to directions with what to do with jumper wires. You could get instruction sheet on stat from the maker, I'd imagine.
Do you have newer style programmable stat? If so, someone probably changed it and miswired something and/or did not maybe pay attention to directions with what to do with jumper wires. You could get instruction sheet on stat from the maker, I'd imagine.
swanie23
04-25-09, 03:49 PM
The thing is that when the operation mode is HEAT and the fan mode is AUTO, when the heat kicks on the AC compressor does NOT switch on. That leads me to believe that the blower is not completely shorted to the AC. There's also no visible jumper on the thermostat or furnace side. Can anyone confirm -- is what I am experiencing definitely not correct? If so, what could be wrong here?
HVAC Mech.
04-25-09, 06:07 PM
During the heating cycle, the normally open fan relay is not powered and the blower is operated by a heat activated fan switch mounted on the heat exchanger, or a fan delay switch.
During cooling, 'G' powers that normally open relay switching the high voltage to bring on the blower. When set to 'fan on' it's powered all the time. Set to 'fan auto' it comes on through the Tstat on a call for cooling.
If the stat is wired OK, then a wire could be on the wrong terminal at the fan center. Or the relay could be toast.
Tom Beer 4U2
During cooling, 'G' powers that normally open relay switching the high voltage to bring on the blower. When set to 'fan on' it's powered all the time. Set to 'fan auto' it comes on through the Tstat on a call for cooling.
If the stat is wired OK, then a wire could be on the wrong terminal at the fan center. Or the relay could be toast.
Tom Beer 4U2