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AC/Heater Fan would not shut off, then....

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http://boards.diynetwork.com/eve/forums/a/tpc/f/9221916776/m/6943941377

Aug 18, 2013, 10:32 AM
tstex
AC/Heater Fan would not shut off, then....
Good Morning to All,

Have a 2002 Payne Electric AC/Heating Unit. Has been working fine, then this morning the fan kept running. It was in the normal Auto / Cool Mode to run the AC.

No matter what I did at the thermostat, I could not turn off the fan motor. Went to the electrical box and turned-off the AC Unit 50amp breaker. This shut the blower fan off. During all phases of checking the unit, I waiting 2-3 minutes bc I know there is a time delay, but this did not matter.

With thermostat in the off position, I flipper the breaker back on and the fan was running again. I decided to test the thermostat/condensing unit so I turned the temp down and hear the outside compressor condensing unit kick in. The air started cooling and when it reached the temp set, the outside condensing unit cut off, then the normal 1-2 minute delay of the fan also worked and the fan/blower inside cut off. Now it was working.

I waited 10 minutes and decided to lower the temp more and the unit turned on, cycled and both inside and outside units cut off as normal.

Does anyone know why the fan was stuck on initially and could only be turned off via the breaker? Was something stuck and now it is not? Can this happen again, or are there any things I need to do to further troubleshoot it?

Thank you very much,
tstex
Aug 18, 2013, 12:08 PM
Jaybee
It will be difficult to trouble shoot as long as it is running properly.

It could be a one-time or rare event: Bad relay or solenoid that could be randomly sticking. Often with newer electronic controls, cutting the power will "reboot" the system to get things working correctly again (although it sounds like this didn't directly help in your case).

I would let it go and monitor the system to see if it does it again. If it does, your best repair path is to call in your H/A service guy. Odds are they can find something like this i a few minutes and have the parts needed to fix it.


Jaybee
Aug 19, 2013, 09:46 AM
tstex
Thanks Jaybee.

I am going to keep it under close watch, but since it is a weekend place, hard to monitor all the time.

Since this is not a real DIY and rarely an issue, calling the tech seems to be the most viable option. However, I will have to do this when/if the problem reduplicates, plus it will be on the weekend.

regards,
tstex
Aug 19, 2013, 11:17 AM
swschrad
I wouldn't hesitate to call it a welded/pitted relay contact. the relay is not an expensive part, which is some of the reason it hung Wink some of them have enough slop sideways to jam the contacts on the side of the fixed contact arm.

next time around, just for jollies, pull the breaker, tap the relays, put the covers on the unit again and turn on power. that's as close as you can get to a fault diagnosis without knowing the unit.


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