Heat pump AHU fan runs continuously

barker7 · #1 Jul 3, 2006, 06:47 AM

I have a 12 year old Trane Xe1000 heat pump. Recently I noticed that the fan keeps running continuously even when the outside unit turns off. It's as if the tstat fan switch is set to On (it's not) instead of Auto. I tried a few things:

1) In the tstat (weathertron) I disconnected the fan control wire (green). Fan kept running.

2) I killed the power via the breaker. System shut down (including the fan). After re-powering the system, the fan DID properly cut off after the cooling cycle. But a day later, the problem is back

I opened the AHU access panel and according to the wiring diagram there is a fan delay relay (FDR). That could be sticking. I've also seen some other posts around the internet talking about the FDR on a Trane. What's the best way to check this relay (I'm experienced (and cautious) around electricity).
Wha other components could fail?

Thanks

Mitch



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