Trane xr80 not blowing hot air. Red light blinks 4 times.


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Old 01-04-16, 08:52 PM
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Trane xr80 not blowing hot air. Red light blinks 4 times.

Hi,
First, I let my filter stay dirty for too long. The furnace was running, but no heat was coming out. So I changed the filter. But nothing.
I cleaned the limit switch with a cloth because I read the 4 blinking lights indicated something was wrong with it, but that didn't help. I turned the furnace back on, but, like always, the flames light up, theres the normal hum like it's about to start blowing air, but no hot air is being forcibly pushed out via the loud fan. I can only hear small sound with hot air barely seeping through my vents.
Just checked, while keeping the door switched depressed, I fired up the heat and the blower fan(?) won't spin, even though while the flames ignite and everything.

Could the blower fan be the problem?
Or is the the limit switch (indicated by the blinking 4 times) causing the fan not to spin? Like, do you think I have to get a new limit switch and test that first.
How do I determine what the issue is? Or should I just call someone to fix it, and how much am I looking at?

I'm just in a serious bind because it's 5 degress, and I have two kids in the house. Although they have a heater in their room, and spend the day at school, it's quite cold in here. Thanks for you help in advance!

 
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Old 01-04-16, 08:56 PM
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Welcome to the forums.

The four flash code is for high heat limit in the heat exchanger. If the blower is not running... that is the problem.

Put the stat in FAN ON mode, hold the blower door switch in and see if you can use a stick to start the blower spinning. if the blower starts spinning.... you could just have a defective starting capacitor. That should be inside near the blower motor.

Let us know how the stick start works out.
 
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Old 01-04-16, 10:51 PM
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It worked! But...

I put the thermostat's fan seeing from Auto to On, and tried the stick thing and didn't work. However, when I put the heat on, put the fan back to auto, kept the safety switch behind the door depressed, and did the stick thing, it worked!

But I still need to go out and get this starting capacitor, right. Because the next time the heat cuts off, and tries to turn back on later, the blower fan won't be able to start with me using the stick I assume?

So where should I get one of these? How much am I looking at spending? Are they relatively easy to install? Does this mean my Limit Switch is totally fine?

Thank you so so much for the help!. My fingers, toes, and kids thank you too!
 
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Old 01-04-16, 11:27 PM
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The capacitor should be a silver can inside the blower compartment. It will be connected to the wiring that comes out of the blower motor. Make sure the furnace is turned off before touching the wiring.

On that part will be its specs. It'll be something like 5mfd at XXXvac.

The limit switches hardly ever go bad. It appears to have been cycling due to the blower motor not running. There is no guarantee that the capacitor is the problem. The cap will be around $10-15 which is a lot less than the $200 for a blower motor.

If you have an HVAC supply place in the area..... take the cap in and say you need one. It may look a little different. That's ok. Don't call ahead and ask if they carry them. They do but many won't help non techs. If you walk in....most will take care of you. Tell em' it's a "cash" sale.

Some misc caps...

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Watch this video..... it's not exactly yours but it should be similar... it'll show you what you are looking for and how to discharge the capacitor with a screwdriver before removing the wires.

you tube/watch?v=SPIZEFzalgI
 
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Old 01-06-16, 06:58 AM
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New Capacitor didn't work...

First, thanks for everything so far.

I was finally able to get a new capacitor this morning, and it didn't help the blower start on it's own. I actually couldn't even get the fan to spin with a push start either.

I tested the old Capacitor to see if the new one was a dud, but that wouldn't start on its own or get push started either. Up to now, I had been able to get it started by pushing it (or at least it worked 7/10 or so times). When I had been able to push start it, it would only go for about 20 mins, get up to like 52 degrees, then stop spinning.

Any ideas now, since it's not the cap? Is it the blower? Is it the big circuit board thing? Am I out of the realm of fixing it myself by tonight? Last night and this morning were unbearable. THanks a lot. I don't know if any of the attached pics help...

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Old 01-06-16, 12:23 PM
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It sounds like the fan motor isn't starting reliably.

The fan on switch may not be connected to turn on the fan.

What you are doing above is following the ignition sequence for the furnace so that the timer on the circuit board turns on the power to the fan to start it up.

You need to follow that process repeatedly to determine if that sequence is being interrupted with the fan motor not switchin on when it should.

At that point, you need to measure the AC voltage being applied to the fan motor. The circuit board should be turning on 120 VAC to operate the fan motor.

If that voltage is being turned on and the fan motor doesn't start reliably, you probably have a bad fan motor.

If that 120 VAC is not being turned on reliably by the circuit board, or the voltage is significantly below 120 VAC, you have a bad circuit board that needs to be replaced.
 
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Old 01-06-16, 05:11 PM
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Ok. Got a new blower motor today, finally installed it. Fan started spinning on its on, without help this time. The old one was definitely seized. Would be great but..

Now it's only blowing cold air!The flames don't seem to be coming on now. They were all yesterday when it was testing it, even today.

Is it more likely I accidentally disconnected something just tonight... Or when I was plugging in the new blower motors wires, I plugged them into the wrong ports? (There were a couple colors that weren't the same. I tried matching them up by comparing them to the labels on the old motor). Could that affect something not lighting?

Might my igniter (?) Be shot all of a sudden? Please help!!
 
 

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