Trane / American Standard air handler blower fan never shuts off

Flt_Simulation

I just bought a 10 year old house that has a split HVAC system (outside A/C unit with an inside air handler/electric heat unit).

The air handler is a Trane model #TWE048C14

Even though the thermostat is in the Fan Auto position, the blower in the air handler continually runs (even when the A/C compressor outside turns off)

I replaced the old Honeywell wall mounted digital thermostat with a brand new Honeywell touch screen thermostat in hopes that the new thermostat would fix this problem, but it did not. Everthing is wired correctly. In fact, even when I remove the new thermostat from the wall, the air handler blower always runs. The only way to get it to turn off is by flipping off the air handler's circuit breaker in the main circuit breaker panel.

From what I have read on various internet sites, there are many parts in the common residential air handler that could cause this problem ....

1. Sequencer

2. Fan Relay

3. Contactor

4. Circuit Board

I am hoping someone here might have previous experiance with these Trane / American Standard air handlers that might lead me in the right direction with this. Maybe my Trane don't have all 4 of the items listed above, but maybe one of the parts listed above are common in these Trane units that cause the blower fan to keep running 24/7.

Any help would be very much appreciated.

Ron,

hvactech126

Your AHU uses a printed circuit board with a relay on it to control the fan. Replace the PCB.

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Flt_Simulation

I did some more searching. It looks like this part is what usually fails in the Trane / American Standard air handlers, and causes the fan to run continually:

Fan Time Delay Relay (replacement P/N: RLY02807)

(various websites selling this part)


http://www.amazon.com/RLY02807-RLY02.../dp/B003GQEZJM

http://shortyshvac.com/index.php?mai...oducts_id=1158

http://www.myhvacparts.com/store/tra...-rly-02257.php

http://www.hvacpartsshop.com/rly0280...elayrelay.aspx

Flt_Simulation

Thanks ... I guess we posted at the same time. Looks like that PCB also includes the Fan Time Delay Relay (all in one part)

Not expensive either.

Now, I wonder how hard it is to get to this part inside the air handler?

Ron,

Flt_Simulation

ttt ...

Flt_Simulation

Just to let eveyone know ... The Time Delay Relay consists of both a printed circuit board and the relay all in one.

Well, I installed a new Time Delay Relay I bought online from Shortys' HVAC Supplies for $35 delivered to the door.

Installed it ... and everything now works perfectly! Now when the thermostat is in "Auto Fan" mode, the scroll fan in the air handler turns off after the AC compressor outside shuts off when it's inbetween cooling cycles .... don't run 24/7 like it used to.

Happy!

.

AirstarFilters

Original # is RLY01168, NLA way Trane or American Standard, replaced by the RLY2807 which requires basic rewiring.

However the Honeywell ST82D1004 is an exact replacement to the RLY01169 and readily available.

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Flt_Simulation

The RLY02807 I bought works fine, but you are correct about the wireing.

The original Time Delay Relay I removed from my Trane air handler looks completely different from the RLY02807, The wires going to the relay are in a different place ... but the instructions that come with the RLY02807 show both the pins that are on the old original Time Delaty Relay and the new replacement RLY20807 ... so if you follow that, you can out your wires on the new unit and it works perfectly.

And the price is great at $35 to the door!

Anyway, it's working like it's supposed to now

Ron,