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termy · Jul 5, 2009, 04:09 PM

It is getting hot outside, and my AC is deciding not to work. The fan inside will not turn on only when in cool mode. It is a Concord unit. Here is what I know..

Outdoor fan works properly as well as the compressor.
Indoor fan turns freely.
Indoor fan works when in heat mode.
Indoor fan will not work in Cool mode.
Indoor furnace part drips water out of the unit, in the past, this has been due to a clog in the tube.. which I Normally vaccuum out at the exit.. and it works.. this year It continued to leak out of the unit and not drain out of the tube.. This tube is very long and wraps around the room to the sink.

IF anyone has any ideas.. I would love to figure this one out.

Thank you..

siberianair · Jul 5, 2009, 05:07 PM

Need to try and drain tube another way.. maybe compressed air or replace the p trap if therte is one.
Water might have damaged the relay, control board or the fan. The fans usually have several windings and speeds. Possible the ac speed is shorted out. Call a the in to diagnos.

termy · Jul 8, 2009, 04:17 AM

Originally Posted by siberianair

need to try and drain tube another way.. maybe compressed air or replace the p trap if therte is one.
water might have damaged the relay, control board or the fan. the fans usually have several windings and speeds. possable the ac speed is shorted out. call a teh in to diagnos.

The leak was due to the drain pipe that was wrapped around the room not being always level or downward allowing gravity to drain the water. It was backing up. That I have adjusted.

I am not sure that there are different speeds on the fan motor. There is a only transformer hooked to a relay and only 2 wires run to the fan. So the fan really could only have 2 modes of operation on and off.
There are only 2 relays on the circuit board, and one of them is for the kill switch and I'm guessing the other is for the fan control.
Since the fan turns on in heat mode, I would have to assume that the relay works. For some reason the relay isn't fired in AC mode.. and the outdoor fan and compressor come on when they are supposed to.

I want to avoid paying a tech to come out, charge labor and outlandish prices for a board I may be able to fix myself for a few dollars. My wife does not trust the local HVAC companies in this recession. We know a HVAC tech that charged his own parents excessive labor and uneeded parts so he could get a better commission. This was discovered when the tech was bragging to someone else about it.. and it got back to the parents.

siberianair · Jul 8, 2009, 01:41 PM

If it is the board you can try to order one online... most boards run about 150 to 400 dollars. There is no way to fix a board. If there is a problem with the board it needs replaced.

termy · Jul 15, 2009, 04:36 AM

The AC worked perfectly well for one day.
I am a little puzzled though.
When in Heat mode, the SPDT relay that goes to the fan is closed and the fan goes on. There is 120V AC present from "Heat Fan "on the control board.
However.. when in AC mode, the SAME SPDT relay (There is only one on the board plus cutoff relay). "feels" and sounds like it is energizing the circuit as well. However the fan does not turn on. There is 0V present at "Cool Fan". I removed the load (fan) and there was still a 0V present.
Note: the AC, Heat, outdoor unit are all triggered by the stat on the control board at the same contact. Which is confusing me... because why would one work and not the other.
Control Board: Armstrong 45692-001 (Honeywell ST9160B 1068 )

siberianair · Jul 15, 2009, 04:51 AM

There is a good chance that the back of the baord is fried, or a winding on beard, or resistor on board...
I know your trying to do this on your own, but it might be time to call someone in. boards are very tricky and touching them wrong with your bare hands will ruin them.