Furnace not working

[sun47me1208]

My front furnace quit working. I can hear the thermostat click to request for heat but the furnace does not do anything. The rear furnace works. So I dont think it is the thermostat. I measured 12.5 volts at the Red wire on the furnace and also I verified that it has 12V at the switch (it only had 12v on one terminal of the switch when in off position and 12V on both when on). The LED on the circuit board does not light, and blower does not function . Normally I hear the blower first before I hear the ignition fires up. Is it safe to assume that the circuit board is bad? Is there any other things I can check before I order a circuit board? ( I have checked that there is no obstruction in the exhaust. Thank is advance

[Skip426]

Could you add the furnace manufacturer and model to your post .

Most RV parts and repair shops will have equipment to test the board ; if you take the board in .

[Teamfoxy]

You could see if there is voltage at the blower itself and if the squirrel cage turns freely. Also see if the blower works when powered directly.
I would suggest downloading the service manuals for your appliances directly from the manufacturers website. They all have troubleshooting guides that you can follow step by step.

[dirtbiker]

I have a winnie site seer and the furnace quit working in the middle of the night on my last trip. I have a Suburban m/n sf30 furnace and like you the thermostat clicks but the fan never comes on. (I can faintly hear something click in the furnace area a second or two after the thermosat clicks) I like you am searching for answers. I replaced the thermostat and the modular board and have the same results still. The blower works . I removed the furnace and checked the various switches and they all seem to test ok with an ohm meter as to whether they are open or closed. I will keep checking here to see if any answers should come your way.

[Old-Biscuit]

Originally Posted by sun47me1208

My front furnace quit working. I can hear the thermostat click to request for heat but the furnace does not do anything. The rear furnace works. So I dont think it is the thermostat. I measured 12.5 volts at the Red wire on the furnace and also I verified that it has 12V at the switch (it only had 12v on one terminal of the switch when in off position and 12V on both when on). The LED on the circuit board does not light, and blower does not function . Normally I hear the blower first before I hear the ignition fires up. Is it safe to assume that the circuit board is bad? Is there any other things I can check before I order a circuit board? ( I have checked that there is no obstruction in the exhaust. Thank is advance

12VDC to/thru that switch which is the On/Off Circuit Breaker Switch
DC from that switch goes to the Power Circuit on the circuit board which will send DC to motor via Blower Circuit WHEN DC from thermostat comes back to circuit board
(typically BLUE wire at the multi-pin connector on circuit board)
So if you have DC from Thermostat to circuit board then Circuit Board is Issue


***Not knowing WHICH Brand/Model of furnace or year

[sun47me1208]

Sorry for the late reply, The commander has me running around. The manufacturer it Atwood Mobile Products. Model 8526-IV DCLP. The squrrel cage is free to spin. I will measure the blue line maybe tomorrow if commander does not have a place to go.

[amosnandy]

This is the best quick troubleshooting guide I have seen.

https://www.youtube.com/watch?v=0t8vRuGdZLw

[Old-Biscuit]

Wiring Diagram for that 8525-IV



RED 12VDC+ from Fused source>>>>On/Off CB AND Back to Thermostat (Blue 12VDC+)
***Red goes to PWR on circuit board

When thermostat CLOSES 12VDC+ comes back from thermostat>>>>Sail Switch AND to Circuit Board at the multi-pin connector (White wire/Blue wire/Red Wire/Yellow wire)
When the Circuit board gets that 12VDC+ from thermostat it sends 12VDC+ to motor (BLW)

No Red Light on circuit board doesn't mean anything
Red Light is an ERROR Code
RED SOLID.........Internal Fault (Bad board)
Red 1x flashing ...Limit Switch/Airflow
Red 2x flashing ...Flame Sense Fault
Red 3x flashing ...Ignition Lockout

Your issue is 12VDC+ going to/coming from circuit board

[sun47me1208]

Thanks Old Biscuit. The commander has places to go and I have decided tohave it looked at when we get back to MI. The rear heater works so she is not really concerned. Thanks you to all who answered my posting


sun47me1208
2014 Fleetwood Excursion 33D
2019 GMC Canyon SLT

[Fiesta48]

Just replaced the sail micro-switch inside the blower housing on the same furnace. Tested ok for continuity but would not take current (amps). Of course it went out on the coldest day this winter. The high temp cutoff switch could be bad or the circuit board. Try the sail switch first, cheapest and easiest to replace. Bought mine on Ebay. Just search Mfgr, model # and sail switch.

[Old-Biscuit]

Originally Posted by Fiesta48

Just replaced the sail micro-switch inside the blower housing on the same furnace. Tested ok for continuity but would not take current (amps). Of course it went out on the coldest day this winter. The high temp cutoff switch could be bad or the circuit board. Try the sail switch first, cheapest and easiest to replace. Bought mine on Ebay. Just search Mfgr, model # and sail switch.

Furnace Fan will run even with bad sail switch or limit switch
**Sail Switch must show open or circuit board will not allow anything to function

Maybe OP will update post if he found/fixed the issue

[dirtbiker]

Originally Posted by sun47me1208

My front furnace quit working. I can hear the thermostat click to request for heat but the furnace does not do anything. The rear furnace works. So I dont think it is the thermostat. I measured 12.5 volts at the Red wire on the furnace and also I verified that it has 12V at the switch (it only had 12v on one terminal of the switch when in off position and 12V on both when on). The LED on the circuit board does not light, and blower does not function . Normally I hear the blower first before I hear the ignition fires up. Is it safe to assume that the circuit board is bad? Is there any other things I can check before I order a circuit board? ( I have checked that there is no obstruction in the exhaust. Thank is advance

Old biscuit gave me the info needed to check out my problem but still after checking everything i had the same problem. I had already replaced the circuit board. still had same problem. I replaced the thermostat and still had same problem! I checked all switches with an ohmmeter and they tested good. I followed advice of shorting the two blue wires to mock a thermostat telling the blower to come on. While I had the circuit board in my hands and getting ready to check my voltage to the board my fan started blowing! Turns out that the modular connector that connects to the circuit board had a loose connection and when I tested voltage I checked at the modular connector not knowing that it was an intermittent connection to the board itself. I was able to adjust the connector so it was a tighter fit and all was ok. I even put the old board back but still had my original problem again proving the board was bad and also a bad connection. I put the new board back in and all has tested fine since. Sorry to be so long winded and so long to respond. I am not real computer literate and am not even sure at this time that I am posting this in the right -place. Hope you solved your problem by now also. These people people on this IRV2 site are so great in helping as much as they do. Thanks to all who responded.