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Bob 09-02-2006 12:33 PM

Blower Won't Come On
I have a Trane XE90 furnace with A/C. The other day the blower just suddenly stopped but the A/C continued to work. On the thermostat I switched to just Fan but still nothing. When I switched to just Heat, the gas ignited but the blower still had no power. I looked at the circuit board and a little red LED light blinks about every second. It seems like the motor is not getting any power. Does anyone know if the problem is either one of the following:

1) Bad circuit board. Is the blinking light on a Trane XE 90 mean that the board is fine?
2) Bad capacitator. How do I check to see if it is still good?
3) Motor is shot. There was no overheated smell when I checked it to see why the blower sunddenly quit. I spun the blower and it spins freely so it is not seized. Could it be a ground wire or any other wire? How do I check to see if power is going to the motor?
4)Thermostat. Could it be the mechanism that controls the fan is shot? Or is that not possible?

Your suggestions, if you know or if you've ever experinenced this, would be a great help.



glennjanie 09-02-2006 02:01 PM

Hi Bob and Welcome to the Forum:
I'm sorry the heat and a/c companies started using computer boards, they take away all logic.
A Trane dealer can look in a book and tell you exactly what is wrong by the blinking but most of the rest of us can't.
Many Trane furnaces and a/c's have direct current motors in order to get the infinite speeds for top efficeincy, which just complicates things even more.
To check the capacitor; take the capicitor leads off , it has to be discharged by grounding, then put the ohm meter on the leads and it should go from somewhere near 1,000 ohms to zero rather quickly.
Two out of three problems I have had to troubleshoot were just a loose wire, so check them throughly. Using a volt meter, touch the motor leads where they are plugged into the board one at a time while grounding the other lead, that will tell you if the motor is getting power. Don't touch anything in the thermostat; there is one contact in there that blows the whole thermostat if you touch it.
The purpose of the board is to get the Trane dealer out to do the troubleshooting for you, for a nominal fee ($50 to $75). Let us know how it works out for you.

Bob 09-03-2006 05:20 PM

Thanks for getting back Glenn.

Yea, I hear ya'. The boards throw in a monkey wrench and keeps you guessing.

Anyway. I checked the leads and they have no power going to the motor. When I turn the power on the board clicks twice, the red light comes on, then clicks another two times and the light starts to flash. A slight electrical buzz is heard coming from the board as if the flow is stuck. The Diagnistic Code for a slow flashing light is NORMAL - NO CALL FOR HEAT. CONTINUOUS ON means REPLACE CONTROL. As per the code it should not be the board but yet no current flows to the motor.

So, if there is no curret flowing to the motor then that rules out the capacitor and the motor, right? That just leaves the board and the relay. Are the clicking noises acually coming from the board or the relay? Could it be a relay problem that's not kicking in the fan. I checked all the connectors going into the board and none are loose.

Also, are there places where I can take the relay and board to get tested?

Look forward to hearing from you!


glennjanie 09-03-2006 09:57 PM

Hey Bob:
Yes, the relay may be doing the ticking noise. It may even be a micro relay on the board itself. They build in time delays for starting in order to prove the flame or that the compressor is working. If you feel the relay is faulty you could take it off, mark where every wire goes and put a tape label on each wire; take the relay to a supply house and get another like it. They will have 40 or 50 different relays that look very much alike but, if you have the old one they can match it for you. If its afull service supplier they may even test the relay for you. The buzzing noise from the relay means there is a contact inside it that has arced too many times and it needs to be repalced.
The only way I would think you could get the circut board tested would be by a Trane dealer. I wish you well my friend.

Bob 09-04-2006 10:01 AM

Thanks Glenn!

I'll let you know what the problem is once I get the parts tested.


Bob 09-05-2006 02:28 PM

I wasn't able to get the parts tested by anyone after calling around so I decided to to have a tehnician to do a diagnostic. I had earlier considered taking the board off and see if anything behind was burnt but decided to play it safe. Turns out it was the board, there was a small burn mark on the relay. Hindsight's always 20-20.

Anyone out there know where I can get a new Circuit Board for a Trane XE90? Model #TUC060C936B6.


Hube 09-06-2006 11:09 AM

[QUOTE=Bob]Anyone out there know where I can get a new Circuit Board for a Trane XE90? Model #TUC060C936B6.
************************************************** *********
Maybe you should try asking a TRANE DEALER,that way you can find out for sure.
Make sure while your at it you ask how much it is too.

brianky 12-17-2008 07:22 PM

XE90 Blower Problem
I seem to be having a similar problem in that at random times when my furnace is suppose to kick on, I just hear a hum. Nothing else happens. The indicator light is blinking no heat call (slow flash). It seems that when I turn the system off or disconnect the power for a period of time and then turn it on or reconnect the power, it begins to function properly. When it works properly, I can see exhaust coming out the vent outside the house, heat comes through the vents inside the house...etc.

I have had a service tech come out and he thinks the motor and possibly the fan wheel is going bad. ...keeps mentioning something about bearings heating up (He does not use the term bearing, but I can't remember his exact term.) Says when they heat up, they don't allow the fan wheel to turn and it won't allow the motor to run. He checked the "draw" on the motor and said that it may be a little high, but not much at all. He seemed to be reaching for a solution.

Before I drop the close to $700 to replace the motor and fan wheel, anyone have any ideas? I figure as long as I can keep getting it to come back on, I will wait until I try to discover a solution. Thanks for any help I can get!

btw: The same techs just installed a Carrier 2.5 ton heat pump over the summer. They say that portion of the system is working fine. It just seems to be the blower/fan wheel...

Thanks again!

glennjanie 12-17-2008 09:18 PM

Welcome Brian:
Blower wheels don't just 'go bad', they can only be damaged. The technician was probably talking about bushings in the motor but I would not expect to see bushings in a motor on a Trane unit; more likely ball or roller bearings. Has the motor been oiled? If there is 'not much draw' on the motor, there is no problem with it.
Let's look at capacitors, board and relays, the more likely problem and a lot less cost.

glennjanie 12-17-2008 09:26 PM

Hello Brian:
Just a follow-up, something is not stacking up here. You said you can see exhaust from the vent but later you said the tech had installed a heat pump, apperantly on this same system.
Is the heat pump a mistake or did they actually install a heat pump to a furnace system? That is really squirlley; perhaps you need to ask for a license. If they can't produce one, call the local inspector.

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