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rojorin 07-24-2012 11:23 AM

Armstrong G6A100DC13-15 Blower Issue
This started happening last AC season and need some help figuring it out. When I put on the AC and set the fan switch on the TStat to Auto at times the condenser will continue to run and the furnace blower will seem to get stuck off while the condenser still runs.

Removed the furnace door and played with the door switch and the fan will come on for a few seconds and then turn off. After a while the fan will come back on and run normally. What is interesting is the fan runs just fine during the heating season. Turns on and off appropriately for heating, just not for the AC.

This is an issue as the condenser line that runs thru my basement ceiling will begin to sweat and has stained thru the ceiling. I am assuming this is due to the condenser running the the blower not running.

Any help would be greatly appreciated.


turnermech 07-24-2012 01:53 PM

sweating has little to do with the fan. The large refirigerant line needs to be insulated better if it is sweating and staining the ceiling. if the fan stops working wile the outside unit is still running the line and coil will freeze. when it melts it can stain the celing. it would only freeze at gaps in the insulation of the lineset where air could get to it.

The door switch should shut both the indoor an outdoor units off. Most Heat pumps use same controls (tstat termials, wire, relay) for heating and cooling fan so I can not explain why your blower problem is only in the summer.

What type of sytem do you have?

rojorin 07-24-2012 01:59 PM

I would say then it must be freezing and melting when the blower starts again because the outside condenser fan is running without the furnace blower fan running.

I have a Armstrong Hot Air Furnace with a Goodman condenser outside for AC. The AC line is wrapped in a black insulation so it should have sufficient insulation. The issue seems to be the blower not running while the condenser fan is running.

turnermech 07-24-2012 03:07 PM

for a furnace you have severl causes of blower not running in A/C.
bad tstat or bad connection at the tstat (G terminal)
bad fan board/relay (is it oil or gas furnace?)
defective high speed on the motor (assuming cooling is set to high speed)

it is possible the fan is running everytime it should but other factors are freezing the coil and giving the impression the fan is not running. A frozen coil will block all air flow and nothing will come out the vents even though the fan is running. Dirty air filters, and low refrigerant charges are the main causes of frozen coils where the blower is not the cause.

rojorin 07-24-2012 04:31 PM

It is a gas furnace.

Coils are not freezing, I know the blower is not running as I am standing next to the furnace. Not relying on air movement from room vents. I am guessing a bad fan relay. Is this something that I can change myself? I switched Tstats and it did the same thing so unless both Tstats where bad (unlikely) then it must be a bad fan board/relay. If it was a bad blower it wouldn't work with the heat, which it does just fine. Filter has been changed and is not dirty. Had the AC serviced a month ago and refrigerent was fine. Service tech couldn't reproduce the blower issue and said all was fine.

This is driving me crazy. I can play with the blower cutoff switch and get it to come on for a few seconds and then it cuts out. Then it will come on and run for a few hours and then cut out. It seems to be running now but I know it will stop blowing in a matter of time. Can't be good to stop and start so many times.

turnermech 07-24-2012 04:45 PM

the fan is controled by a circuit board. The relay for the fan is on the board. the whole board would need to be changed. If you have a way to test the capacitors MFD rating (will require a meter with that ability) do it before replacing the motor. If you cant test it change it before the motor as they are fairly cheap and easy. The fan can be defective on one speed (heating) and not another (cooling), but it does not happen offen. Does the motor ever stop when the tstat is set to fan on (this in many cases is a different speed than heating or cooling as well as a different relay on the circuit board?

rojorin 07-25-2012 07:44 AM

First off thank you Tunermech for you help. I really appreciate you taking the time to respond!

My Tstat has two switches one that is for the fan that is Auto and On. The other says Cool, Heat and Off. Most of the blower issues happen with the fan switch on Auto. It seems to run fine when I have it just switched to On but it doesn't stop blowing when the temp is reached which sort of defeats the purpose. The condenser fan stops when the temp is reached.

It has happened even when switched to fan ON just not as frequently. Last night it stopped when it was switched to on, I went down to the furnace and played with the door switch, clicking it a few times and got it running again. It seems to be some sort of relay that is getting stuck.

I don't seem to notice a different fan speed from heating and cooling when I observe each one running. Would I be able to tell the difference visually?

turnermech 07-25-2012 09:18 AM

fan on at the tstat would control indoor blower only. and yes blower would stay running. If you have no problems with it set to on it would eliminate some possible problems. It appears by you post you have problems with it set to on as well as auto. If you have not already done so check or just change the capacitor. If that does not do it try to bypass the door switch as you keep mentioning that it works when you push it in. the door switch should have two wires on it. With the power off connect these together. do it in away you can put it back if problem continues.

the printed circut board in the furnace will have terminals labled heat, cool and fan. there would be wires connected to each. each wire is energized by a different relay made to the control board. these wires run to the fan motor and turn on the speeds of the motor. typical motor speed wire color are black=high, blue=med high, yellow=med low, red= low

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