TRANE XE90 getting no power, no red light

kok328 said:

This isn't good. You should only be seeing power at the top right (blk1 & blk2).
Also, remove the 30 amp fuse ASAP !!!!!
If the 5 amp blew then you have a short somewhere in the control circuits 24VAC as explained earlier.

Click to expand...

The fuse blew a couple years ago, but I'll change it back. When I tested, I put one end of the tester on the left side and the other on the right side. I guess I should touch one end of the tester to a screw and the other to a ground, eh? My bad. I'll try that tomorrow.

I'll also try to find a new wire to run from the top right screw to the door switch.

The 30 amp fuse may have brought on these additional problems. It is providing no protection for the circuits on your unit.

Do you understand how to use a volt meter? If you touch both leads to a hot connection you will read 0 . The meter measures differantial . One lead to hot , one lead to common . There is a junction box in that furnace where primary voltage enters. You need to put the meter to that black wire in that box , and a white or ground wire with the other lead.

The very first step here is knowing if the furnace itself is getting power.

I'm bringing this post back to life because I never did get it working. I got a very nice volt meter tester and I am getting 122 V to the door switch, which I bypassed and goes directly into the control board. So yes, the control board is getting power and also the 5A fuse is good.

What's your voltage off the secondary of the transformer?

if you have an owners manual, it should tell you what the slow blink red light means



[ame="https://www.youtube.com/watch?v=iab6PL_B9fY"]https://www.youtube.com/watch?v=iab6PL_B9fY[/ame]

Slow blinking light is "no call for heat" I think. I wish I had any blinking light. LOL

"What's your voltage off the secondary of the transformer?"

Not sure which one I was supposed to read, but

TOP LEFT = .000
BOTTOM LEFT = 122.4
TOP RIGHT = 0.1XX
BOTTOM RIGHT = 0.480

From what I have read, the one on the left is correct at 120V, but should the right side read 24V? OMG, I hope this is it!

Your transformer converts from 120v to 24v.
120v is primary
24v is secondary
Don't know exactly what you checked but this could be a problem.

Mine looks like the one in the picture. I'm guessing one side is the 115 V input and the other is the 24 V output. When I touched each post with one end and grounded the other end, I got the results above. So it looks like there is 115 (122 V in my case) going in, but nothing coming out. Is this right? I'm going to buy the part and switch it out anyway. I'll post back with my results. In the meantime, if anyone wants to confirm my diagnosis, feel free to! Thanks!

sounds right.
[ame]https://www.youtube.com/watch?v=IIGhKLdCk7U[/ame]

Yeah, it's me again. Seems like forever that I have been at this. I just end up finding a work around, like window AC units, portable heaters, etc.

Anyway, right now, I'm getting the "no call for heat" code, slow blinking red light. The problem is, the W connection on the circuit board is throwing sparks and blows the fuse whenever a "call for heat" is initiated. I read elsewhere to try a jumper wire on the control board from the "R" to the "W" and it's throwing sparks until the fuse blows still when I do that. Then, I hooked up another control board that I have (not sure if it works or not), but it does the same thing.

Another test I did (on accident) was touch the "W" (call for heat) wire to the "Y" spot on the control board (this spot calls for the AC to run) and the furnace runs like when you turn the thermostat to the "ON" position (from AUTO). It just blows air out, neither hot nor cold. Neither the AC not the flame kick on.

So something is causing the "W" to spark. Wondering if a wire was plugged into the wrong spot on the control board? One of the last things I did was change the transformer. Could plugging wires to it wrong cause this? Thanks to all who have helped me out up to here and in the future. Kind of fun trying to figure this out anyway, eh? LOL

Sparks are never good, did you measure the voltage you are getting.

http://www.justanswer.com/hvac/7roty-taking-off-thermostat-noticed-spark.html

This is an interesting read, sounds like you may have short like the thermostat is wired wrong.

I read that to test to see if it's the thermostat causing the problem, remove the "R" & "W" wires on the control board and run a jumper from the "R" to the "W" on the control board. This is supposed to make the furnace run, or have a constant "call for heat". I tried this and I got sparks again. When I ran the jumper from the "R" to the "Y", the furnace ran. So the same thing happens when it runs through the thermostat as it does when it does not run through the thermostat. And the wire that was running from the thermostat to "W" was indeed the correct "call for heat" wire because it only became active when I turned on the heat and turned the desired temp up higher than the actual temp. When I did that, that is when the sparks happened. AND I did this with 2 different control boards. They both may be bad, but before I buy yet another control board, I want to make sure I need another.

Next time I work on it, I will check the voltage. What are you wanting me to check the voltage on? In other words, where do I put the red and black wire from the volt meter? LOL

I am just wondering if you are getting more than 24 volts. after that it is above my pay grade? We need someone with more knowledge than me.

[ame]https://www.youtube.com/watch?v=eBYunyrImf0[/ame]
[ame]https://www.youtube.com/watch?v=0HiMJznAKKY[/ame]

The tstat is just a switch , no different than a light switch. When you jump out the red and white terminails your just bypassing the switch and turning the heat mode on . I know that dosn't help you , but just so you understand what your doing .

I take it with out that gauge you can run these tests with a hand full of fuses.

Sorry for the delay. I measured the V on the control board, and when I touch the "R" to the "W" or "Y", the meter read 28.74 on both. Is that what you are wanting?

Now remember what I said earlier. When I jump the "R" to the "W"(heat), it throws sparks. When I jump the "R" to the "Y" (cool), the blower kicks on.

I'm wondering if I connected a wire to the board in the wrong spot elsewhere? Maybe there is a diagram or post showing the correct wiring setup with the other wires on the control board? Or are both of these boards just shot?

I hope this helps. If you need any more info, let me know.

If you are blowing fuses you have a short somewhere, either wiring wrong or wire touching ground somewhere.
I don't know enough to say anything about the board. but if the short is on the board I guess that would be the problem.