Furnace not working

[xraymiller]

Originally Posted by Route 66 Traveler

Have you tried it since you cycled the switch? If that didn't work try removing the furnace 12 volts by removing the fuse for the furnace. Wait a few minutes and reinsert the fuse. I assume you have checked the fuse all ready...


If your knowledge of electronics is limited and you do not have a wiring diagram or schematic it might be to your advantage to seek out a mobile tech in your area. Might save you money in the long run....

I pulled the fuse and checked it again.

I’d say my electronics skills are better than average, but I tend to be more like, give me the steps and I can cook. I’m not much of just cooking on the fly. If that was even a good analogy.

This time I noticed when the thermostat was turned to heat, a red light blinked on the board whether the switch was OFF or on RESET. When we turned off the thermostat the light stopped blinking. Does that give any clues?

[Route 66 Traveler]

On page 8 there is the explanation of the light blinks. If it's a Hard Lockout you need to remove the power for a short period of time in order to reset.


https://manuals.heartlandowners.org/...wood%20AFM.PDF

[xraymiller]

Originally Posted by Route 66 Traveler

On page 8 there is the explanation of the light blinks. If it's a Hard Lockout you need to remove the power for a short period of time in order to reset.


https://manuals.heartlandowners.org/...wood%20AFM.PDF

I went out and counted the blinks and it is 1 w/3 sec which is an Air Flow/ Limit Fault.

What is the next step? I don’t understand an air flow fault when the motor doesn’t even turn on.

[Route 66 Traveler]

Since the light is blinking on the furnace it must be getting the 12 volt power needed to run. Sounds like it might be a thermostat problem to me, but I thought you mentioned at one time the furnace blower was running??

[xraymiller]

Originally Posted by Route 66 Traveler

Since the light is blinking on the furnace it must be getting the 12 volt power needed to run. Sounds like it might be a thermostat problem to me, but I thought you mentioned at one time the furnace blower was running??

No, that was a typo. The blower never ran. I never heard anything in the area of the furnace. Only the thermostat clicked when switching to heat.

[Route 66 Traveler]

Try taking off the cover for the Thermostat and see if there is a mini-fuse on the circuit board. What brand of T-stat is it?

[xraymiller]

Originally Posted by Route 66 Traveler

Try taking off the cover for the Thermostat and see if there is a mini-fuse on the circuit board. What brand of T-stat is it?

It is an RVComfort HC Coleman-Mack. I looked inside and there is a tube style fuse that looks ok.

[Route 66 Traveler]

Would you be able to gently remove it and check it with an OHM meter? Turn it to OFF fiirst. Could be a loose wire from the T-stat to the wiring harness.

[xraymiller]

Originally Posted by Route 66 Traveler

Would you be able to gently remove it and check it with an OHM meter? Turn it to OFF fiirst. Could be a loose wire from the T-stat to the wiring harness.

That number was jumping everywhere. I saw it at 6 then 26, once as high as 120.

[Route 66 Traveler]

On the Ohm setting on your multi-meter touch the leads together and the readout should be Zero on the lowest setting. There is a wheel adjuster to achieve the Zero value. Then touch a lead to each end of the fuse and if the fuse is good it will read Zero also. Anything higher than Zero means the fuse is bad.

[xraymiller]

Originally Posted by Route 66 Traveler

On the Ohm setting on your multi-meter touch the leads together and the readout should be Zero on the lowest setting. There is a wheel adjuster to achieve the Zero value. Then touch a lead to each end of the fuse and if the fuse is good it will read Zero also. Anything higher than Zero means the fuse is bad.

I don’t see a wheel on my multimeter, but the leads read 0. The fuse reads 0 for a brief moment then goes all over the place. It will dance from 4-5, then 0.2 - 0.7, then it will shoot up to the 60’s.

If the fuse is bad, would I have a problem with the A/C, because there’s no problem with that running.?

[Route 66 Traveler]

The fuse should read Zero if good, high resistance or infinity if bad...not sure why your numbers are jumping around. Not sure about the answer to your question.


Look at these and see if one of them match your thermostat:


https://www.airxcel.com/rv/coleman-m...og-thermostats


Or


https://www.airxcel.com/rv/coleman-m...al-thermostats

[xraymiller]

Originally Posted by Route 66 Traveler

The fuse should read Zero if good, high resistance or infinity if bad...not sure why your numbers are jumping around. Not sure about the answer to your question.


Look at these and see if one of them match your thermostat:


https://www.airxcel.com/rv/coleman-m...og-thermostats


Or


https://www.airxcel.com/rv/coleman-m...al-thermostats

It looks like a Coleman Airxcel 8330-3862

[Route 66 Traveler]

That's what mine is. Here is the information sheet:


https://www.airxcel.com/DesktopModul...thermostat.pdf


The white wire goes to the furnace, the yellow to the AC, then it's just +12 and the ground (-12).

[Route 66 Traveler]

I think you might try carefully removing it from the wall and look at the wires. They will be connected to the other wires by wire nuts and they have a tendency to come loose. You might also look at the connections on the furnace end as well. Got to be something simple! The code that you saw on the furnace means the blower wasn't running, therefore the gas would not be turned on.

[xraymiller]

Originally Posted by Route 66 Traveler

I think you might try carefully removing it from the wall and look at the wires. They will be connected to the other wires by wire nuts and they have a tendency to come loose. You might also look at the connections on the furnace end as well. Got to be something simple! The code that you saw on the furnace means the blower wasn't running, therefore the gas would not be turned on.

I tested the thermostat. Put red lead on red, black on blue and got 12volts. Move the black to yellow and got 0.2 I think. Then I told the heat to come on, heard the click, then I got 12V off the yellow.

I did take a peak behind the thermostat and they didn’t use wire nuts, they used those splicers. What I would like to do next is see if I’m getting 12V at the outside panel. Just not sure which wires I’m checking yet.

But, that wil have to wait. The sun is setting and the mosquitos are coming out. I head home tomorrow where I have better internet and can maybe post some pictures.

[Route 66 Traveler]

Have a safe trip. Check the connections at the furnace as well. If the furnace has power, all it takes to turn on is 12volts applied to the white wire.


I'll be off-line as well for a day or two, hope you get it running before too long. Lots of smart guys on this forum....you should get some expert help soon....

[xraymiller]

OK, I think I might have found the culprit, but I would like your opinion.

I checked voltages at the reset switch. When the heat was switched on I had 12V at both connections. I also noticed there was water/moisture in the plastic covering the connector.

Then I followed the wire form the reset switch to the controller board, and I had 12V there as well. I noticed a LOT of corrosion on that blade connector. Then I checked the red wire coming out of the board marked BLO and was only getting 5V.

Correct me if I'm wrong, but it looks like I need a new board. I don't know how so much moisture is getting in there, but maybe a new outside cover too.

[hawkster]

Is the fridge outside panel above the furnace? If yes check the fridge condensation tray. Is it full of water? Have you defrosted lately? Running fridge in humid conditions? Some of us in the south found the tray fills with water and overflows to furnace circuit board from above. I sealed between the two units with silicone and extended the condensation hose outside the vent not using the tray. Mine did this twice (dealer sealed outside furnace panel and it failed again). Have seen three 31ul with this problem.

You may be able to remove circuit board, clean and dry it, and reinstall.

[Screwby]

Yikes, that board looks suspicious. Can you get a can of contact cleaner and use a toothbrush or similar tool to remove the corrosion and see if that helps. I’ve revived quite a few industrial and residential circuit boards with just a good cleaning. Corrosion can cause shorts across circuits and make things act wonky. It’s worth a shot before you go replacing parts.