Gas and Oil Home Heating Furnaces - Carrier 58STA/STX won't light-Please Help!

Ok, I can't get my Carrier 58STA furnace to light up. I have had this problem before....typically every winter for the first lighting. Anyway, it was really cold 3 days ago and I tried to get it to light following the procedure and it wouldn't this time. However, this time, I made the problem worse.

I have knowledge of electrics, lots of troubleshooting experience and a VOM. The furnace kind of reminds of electronic fuel injection.

Ok, after about trying to do the restart procedure three times, I started to try and find out the problem. The error code led was on. I started the restart procedure. I could hear a hum in the furnace but it didn't start. Looking at the error code led, it was flashing 31. I decided to let it keep trying because low gas content can be one of the causes for 31 and the restart procedure has you turn the gas off. I came back and the led was solid. Looking at the instructions it says that you can recall the last LED error code by removing the lead from one side of the Draft SafeGuard Switch. Anyway, I was trying that but I simply could not get the lead off....and I was worried about breaking the switch pulling on it. I tried to use a screwdriver but I shorted the lead out to ground. :wall:

Now I'm getting error code 24 and my thermostat panel is dead. I tried removing the thermostat panel to look for a fuse but could not find any. I'm hoping there is a fuse to fix the "secondary problem" I just created.

Any ideas where this fuse is?

Assuming I can find the fuse and fix it. Any ideas what the original problem is on why this thing won't start?

Thanks in advance for help.

Ok, I found the fuse and its blown...so as soon as I fix that I'll be back at problem 1. if anyone has similar problems, the fuse is on the board once you pull the blower off... Also despite what the instructions tell you to do. To pull the code, what I suggest is that you disconnect power to the unit, pull the connector off the draft guard switch first and short wire it back. Turn the power back and reinitialize the system until the error code returns and use the short wire to do the quick disconnect to read the code. I have no idea why this manufacturer could not afford a $.40 switch to interupt the circuit so the code could be re-read at any time.

Ok, I have replaced the fuse and I'm back to the point I was before. The furnace won't fire up. It makes an electric sound near where the gas enters like a solenoid thats stuck but not as loud as that...more of a hum.

I get error code 31. In my troubshooting manual, that is:

Pressure switch did not close or reopened-- if open longer than 5 mins., inducer shuts off for 15 mins before retry. If opens during blower on-delay period, blower will come on for the select blower off-delay. Check for:
-proper vent sizing.
-low inducer voltage (115v)
-low inlet gas pressure (if LGPS used)
-inadequate combustion air supply.
-disconnected or obstructed pressure tubing.
-defective inducer motor.
-defective pressure switch.
-excessive wind.
-restricted vent.

Thats a lot of stuff. The gas is T'd to second heater so I can see how its the gas. There was a lot of wind...but none now.

How do I go about testing the inducer motor? I guess by the instructions, the inducer motor wants 115v...so would I pull it out and give it 115 volts?
I should be able to test the pressure switch with my ohm meter I would think....I just don't know if I'm especting the switch to be closed, open or read a specific resistance.

Any ideas?

Ok, I measured the pressure switch and it was open. I tried to turn the inducer and it makes a horrible sound...a sqeeking sound. It barely turns. I found a spot on the motor that was free, turned the furnace on and watched the inducer motor turn a 1/4 turn and stop with a squel.

That has to be the problem. Now, is there something that this motor can "rub up" against or are the bearings dried up? It looks like an A/C motor so if its the bearings, I should be able to get at them and give them a bit of oil and possible the problem would be solved. However, it really sounds like the motor is "rubbing" against something because at the free spot...it was free wheeling.

Ok, it appears to basically be a case of cheap chinese garbage. The motor is rubbing against something inside. If I pull back on the motor mount a bit, its free wheeling. The whole motor mount is 1/16 galvinized steel...kind of amazing it can even handle the torque of the motor. However, it has rubber grommets...do these have to be replaced periodically or something? I don't understand how the furnace got to this condition... Normally this component is covered so how would this happen?

You are probably in the best postion to see what modifications you can do.

The rubber grommets are dampers that isolate the metal mount of the motor to the blower housing. If you start bending on this cheap thin metal mount too much you may fatique it and may have to get a new mount kit from a motor shop, be my best guess. If nothing too off-base, maybe you can shim so blower square and away from contacting anything by adding some additional washer(s) on the mounts, where necessary. If new grommets are needed, perhaps motor shop has some of these also.

Ok its fixed...and the furnace is lit and running.

What I did.

I just loosened two of the screws holding the motor. At that point, I couldn't turn the motor at all. I'm not sure what it was hanging up on inside or whether it was the housing or what. I kept jiggling back and forth and suddenly it went free and once it was free, it seemed to be completely free. Then I tightened it back up.

My guess is that the motor was on "too tight." The grommets seem to provide the dampening that is needed. If you keep screwing in the screws, you can eventually screw past the dampening points. So my opinion, is that the screws were assembled too tight...and that would be at the factory. The furnace has never been serviced.

So if you google this post, the answer is check the inducer motor and make sure you can spin it easily. If not, consider just loosening the screws and getting the motor to run freely. I have seen a lot of posts on this problem, but no solutions or you have to pay for the solution.

All done. Beer 4U2

Just wanted to thank you for your diagnosis....a similar thing happened to me. The inducer motor was not spinning during the cycle and when I manually helped it it started to spin. I thought I would need a new motor...I thought bearings were shot. I loosened the 2 screws and shook the motor a little and now it freewheels like before. It still makes a louder than normal sound but it doesn't seem to be hindered right now.
Thanks again.
engg2000

No problem.

My motors fan blades were rubbing against something inside.

You could be describing the symptoms of "dry worn" bearings. 1.) Motor needs help to start. 2.) It makes a louder than normal sound and 3.) it doesn't "come up to full speed". Many of these cheap A/C motors you can get access to the cheap bearings or sleeve bearings. Squirt some oil in there and you probably would be good to go for another 3-4 years. However, if you wait too long and it freezes up, then you stand a chance of burning up the motor.

Make sure with everything 'power off'. You can easily spin the motor and it stays spinning for at least 10 seconds or so. Otherwise try to get access and put some 3-in-1 oil on the sleeve. If you get the right place, you'll instantly see the motor spin much longer.

I would recommend removing the venting and check for birds or squirrels that crawled in there and died which bound up your fan.

:eek:
Mine was metal-2-metal contact....but that seems also a possibility if you hand spun the dead body out of the way. :D

I do have a problem with bats. They seem to be able to squeeze into dark corners easily.

My inducer fan stopped again. Its definitely metal to metal contact. I'm going to remove the assembly and have a look. I loosened the assembly screws (not the screws on the rubber grommets) and it started freewheeling again. I'll remove the whole thing and see whats going on....

The metal-to-metal contact I was hearing was pretty unmistakenable. I could turn it 1/4 turn and then it would rub up against something metal-on-metal. I removed 3 of the 4 screws that were going through the rubber grommets and "loosened" the fourth. I had to jiggle it loose of whatever was binding it and then I retightened the screws in the grommets without "overtightening" them and bottoming out the rubber. It seems to have held so far....but perhaps it will become a yearly or monthly thing...not sure yet.

Hey, if you take it a part and have a digital camera some pictures would be nice of whats inside.

I think its a tolerance issue. I'm assuming there is a rotary fan blade on the end of the motor. And if screwed in too far, it can rub against the housing. Also since the motor mounts are simply 1/16" galvanized or thereabouts, it can simply be bent out of tolerance as well even if its tightened correctly.

I'm betting your bearings are ready to go. Don't take yours apart without a new gasket. I just bought a new assembly for 286 +gst...You can buy the motor/wheel for much much less <$100 I believe, but it wasn't in stock. I need heat today.
I doubt your squirrel cage fan is rubbing on anything. There is 1/4" clearance behind the fan unless your set screw came loose and your fan moved back.
Its easy to take a look, just have a new gasket ready. After I took mine out, it was rotating fine. I tipped it on end and it wouldn't spin...bearings I'm sure because i have black metal particle dust on my desk.
I can't attach photos for some reason. Let me know your email and I can send you pics.

All fixed...perfectly quiet now.
There doesn't appear to be really anything that could rub against the fan blades inside. Either you have debris in the fan area or your bearings are on their way out. If I had time I would have waited for the motor/fan wheel assembly (1 day) but its not very warm today in Edmonton. If its less than 5 years from manufacture, it is still under warranty, so call up Carrier and get your free part :).
engg2000

I believe I'm right at around 3.5-4 years. If Carrier will send me a new one, I will gladly install it.

I would think they would require a "certified Carrier" technician to look at it and install it. I have no had problems though so far since I reset the screws and reinstalled it "level".

I'm not sure what gasket you are referring to? There is a gasket where the motor attaches?

Yes, there is a thin fiberglass gasket between the motor assembly and the furnace. Take a look at the schematic in the carrier document (link below). Replacing assembly was a 10 minute job. It will be a 30 minute job to replace the motor to the old assembly.

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/iik326628-01.pdf

One other thing, the warranty will probably be to the service tech but that company may still charge you for the part (this is how they make money and why the service game is so lucrative). The manufacturer will replace certain parts for 5 years. The parts supplier looked up my furnace to see if it was covered and sold me the part only because I know the Carrier branch manager through my engineering consulting work. If you know an HVAC tech, see if you can deal through them.

Yeh, I don't know any HVAC techs.

That schematic does not look like mine.... In fact, that looks like a vast improvement over the design in mine. Mine screws into some metal tabs that were cut and then bent out of the housing. Theres a good 1/8" play just in how you tighten the screws.

I don't remember seeing a gasket but I really didn't go that far.