Atwood 8531-IV furnace problems please help

[oldmanriver809]

I’m having problems with my Atwood 8531-IV furnace. It will not ignite. The fan runs for 30 seconds then stops for a few seconds then starts back up and will do this over and over but I do not hear the gas valve clicking or the electrode sparking. I’ve tested the gas valve using a 12 volt jumper wire and both solenoids click when I attached the jumper wires. I have already bought and changed the main board, the sail switch, and the limit switch because I figured the gas valve and the electrode weren’t getting power to them. I tried to see if the gas valve and electrode were getting any power sent to them by attaching a test light to the connection but the test light never illuminated when the furnace was cycling. The nights are getting real cold and I am at a loss.. any help would be greatly appreciated. Thanks in advance, Jeff

2008 Jayco Eagle

[topjimmy]

Furnace problems are a bear i have lost count on how many times mine has screwed up I mentioned earlier that my sail switch went out and that fixed it but then a month later it quit again DANG!! i replaced just about every part except one i pulled out the igniter and it looked great and it had the 1/8 of a inch gap but i said what the heck and bought a new one a BAM! all good again ..It is always something:D

[oldmanriver809]

So I bit the bullet, removed my furnace and took it to a RV Technician. He preformed a bench test on it and was able to see everything working well. He said he blew out the combustion chamber and the connections with air but that was all he had to do for it to work. I brought it back and installed it and it still didn’t work but when I was at his shop I noticed that he had connected the two blue wires for the bench test so I did that and it worked. By doing this it apparently bypasses the thermostat. I then quickly ordered a new thermostat, installed it, and it works great! So now I have a nice warm 5th wheel:) Thank you guys who responded to my post with suggestions and insights. Happy camping!! Stay warm.

[topjimmy]

I have also had to replace my control board as well on mine not saying that is it but worth a try or the heck with it and call a RV tech to take a look

[oldmanriver809]

Ok so I checked the Sail Switch with a voltmeter. When I turned on the furnace and the fan was running I had 12 volts, (12.97v) on one side of the Sail switch. I checked the other side with the switch physically pushed with my hand to simulate the fan blowing it and didn’t have 12 volts on the other side. I tried jumping the switch and then starting the furnace but that didn’t allow the furnace to turn on at all. Could it be my thermostat? The air conditioner works fine though.

[oldmanriver809]

Thanks for the response dougrainer and topjimmy! I m heading out to get a voltmeter then I will check the voltage in and out of the new sail switch I have already installed.

[topjimmy]

Just like was said above had the same problem it was the Sail Switch cheap and easy to put in and even if is not that they seem to fail every few years anyway look on You tube and see how to install them

[dougrainer]

Since your problem has stayed the same regardless of replacing all the parts, you need to look at the SAIL SWITCH. The Time delay has no bearing on this type problem. IF the time delay was bad, the fan would not come on. Once the fan operates, the time delay has no bearing on operational issues. You NEED to verify that 12 volts is coming IN and OUT of the sail switch when fan is running.
1. IF the fan motor is NOT good and NOT running at the correct speed(RPM), then the sail switch will not close and NOTHING will happen.
2. IF you do NOT have a minimum of 12 volts or higher the Fan motor will not run at correct speed. Doug

[oldmanriver809]

I’m not sure if my model furnace has one of those relay delay’s on it? I only saw a reset switch other than the board and nothing attached to the outside of the fan housing where other models have it attached.

[oldmanriver809]

Thank you goff1256 I will definitely look into that after work today!

[goff1256]

Replace the relay delay switch it’s still only thing that isn’t new The operating sequence is relay delay turns the fan motor on fan motor goes through I believe the limit switch first or maybe the sale switch first before it could activate the board which then activates the ignition cycle and the gas valve my guess is probably the relay delay switch is not keeping the fan motor running long enough it should run for about 45 seconds before the igniter start