Air Handler Won't Shut Off

18 years ago

Our 11.5 yr old Trane TWH036B140A1 air handler with a Honeywell L6006A Aquastat controller and digital honeywell thermostat does not turn off.

The fan continually runs, even if the thermostat is off. I even took the thermostat off the wall and it still is on. I turned the aquastat to max temp and min temp and its still is on. So the only way I can turn off the fan is using the electrical switch that the electricians put on the air handler. The air handler is in the attic.

The air conditioning works fine, but I don't want the air handler to run 24/7 as I am not made of $$$. So I'm thinking its something to do with the wiring. could the L6006A be faulty? I took the digital thermostat off the wall, so i don't think its that?

Thanks...

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Comments (4)

miken_2008
18 years ago
That Trane AHU has a fan relay inside the control box of the unit the relay is attached to a small PC board so you should have no trouble finding it, this is the likely source of your problem unless you have a couple of control wires getting together the relay is stuck in the closed position you can probably tap it and it will release but you will need to replace it

Here is a link that might be useful: Air Conditioning Repair made Easy
jvotteler
Original Author
18 years ago
Thanks, I am assuming I just shut the power off at the main panel (circuit breaker) before opening anything up... I will try to look at it.

It shuts off every now and then but for the most part is stays on. It never really happened in the winter... Could these relays overheat in an attic?
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zl700
18 years ago
You have an L6006 on an air handler?

Would that be for a hot water coil of a boiler?

The L6006 would be there to close the fan contacts when hot water is present and flowing through the coil right?

Could be the L6006, the air handler relay or the boiler circ, stat or relay also.

If so, need more info, meter readings and tech diagnosis
spdunkle
18 years ago
Just curious how you ended up fixing this, or what exactly caused the problem. I have the same model and the symptoms are identical.
Thanks!