Heatpump freezeups


Old 10-29-12, 01:19 PM
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Heatpump freezeups

My heatpump freezes up periodically. I've had freon checked and filled but still it happens.
Here is what I have noticed:
When it freezes up, the blower unit in the attic (the heat interchange unit) is NOT on. That fan not being on could/would normally be the cause of freezup, would it not?
If I then go to the thermostat (it is a digital thermostat) and flick it on and off a few times (from heat to ac - back and forth a few times until I hear it click) and then reset the temps on the thermostat, the fan comes on and the AC works as it should.

MY AC guy tells me it is time to replace the attic unit. He DID replace the relay in the unit a couple years ago and he tested the relay recently and said it was fine.
But, to me, it seems as if the thermostat is what is messing up. Because again, it freezes, I play with the thermostat a bit and the AC starts to work again......
But it is a digital thermostat and there are no mechanical parts in it to hang up... digital devices don't usually not trip something.... Intigrated circuits don't often get hung up like a relay does......

Interested in hearing other theories, opinions......
I'm in favor of just replacing the thermostat but the AC guy does not seem too sure.......
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Old 10-29-12, 04:22 PM
hvactechfw's Avatar
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There are relays in the thermostat....... I would try replacing it first. And possibly replace the relay as well to be sure.
Old 10-30-12, 03:06 PM
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Take the thermostat off the wall and jumper terminals R and G.

If the fan doesn't come on, the problem is in the air handler or t-stat wiring.

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