Community Forums

giturdun · 04-06-2012, 12:40 PM

Furnace (SF42F) will not work.... Checked all things I could think of and a few more suggestions from the manual (switches, power, etc etc)....It doesn't even make any noise, like its even trying to lite or blow.....Whats up with that ???
It's 10* outside,,,,COLD COLD

jlfbatonrg · 04-07-2012, 07:29 PM

The following assumes you have an older Subruban furnace, since you didn't mention the year and I don't have a suburban manual. Sounds like either the electrical plug on the furnace has come loose, the 12V fuse for the furnace is blown, or the thermostat isn't functioning. First find the furnace fuse and be sure it's OK. Next push the electrical connector into the furnace firmly to be sure it is making contact. Next remover the thermostat from the wall. It will have 3 or 4 wires coming to it. If you have a voltmeter check to see if the red wire has 12Vs. If not, there is a problem with the wiring , fuse, etc, that feeds the thermostat. If you have 12v you should be abe to figure out which wires go through the mercury switch. When you move the temperature setting you should be able to see a spark when the switch makes. If no spark, you should be able to jumper the contacts and see if the furnace blower starts to run. If so the thermostat is not working. This troubleshooting is for the older non digital furnaces. Good luck.

Jim

oldbeek · 04-07-2012, 09:42 PM

Go to Bryantrv.com That site has some good self help service manuals. Also good folks to deal with if need a part. OR go to search above and search furnace problem. Do yo know of rv.net? Chris Bryant is on that forum and possibly this one.

Good man · 04-07-2012, 09:50 PM

giturdun,
Make sure the propane lines are purged by firing up your propane cook top burners for a couple of minutes, until they burn steadily. If you have had the main tank valve turned off or have changed portable or extender tanks, air can get into the system and your LP appliances will be balky to light.
Good luck,
Jim

W4RLR · 04-07-2012, 09:54 PM

I vote for the thermostat. The mobile RV repair guy that fixed my Suburban furnace was tearing out his hair until he called the factory and explained the problem, in my case the furnace would try to light but wouldn't then after a few tries would go into lockout. Replacing the thermostat solved the problem.

camper33 · 04-08-2012, 05:52 AM

If you have a combination t'stat for your air and furnace, check what brand it is. If it is a duo therm, the furnace is controlled by the control in the air conditioner. To test remove the air filter cover. on one side there will be a group of wires coming out of the control. They are low voltage so no concern for shock. usually the furnace wires are blue or blue/white stripe, connected to a red and white. short those two together. If the furnace starts,m open the control box. there is a 3 amp fuse inside. Caution as there is 120 inside the box.
If it is a Coleman, the furnace is controlled by the t'stat directly.. Remove the t'stat from the wall and look for the red 7 white wire, I don't remember the color on the t'stat. short those two together. If the furnace starts, check the 3 amp glass fuse on the back of the t'stat. Hope this helps.