Furnace is making my blood boil, but not my Rv

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
9

92Coronado

New member
Joined
Nov 30, 2016
Posts
1
Ok, help. Please.

Problem. Suburban nt 40 furnace blows, sparks but does not ignite. Pulled the thing out of my 92 coronado, managed to kink the gas line and had to sweat weld a new piece  of copper with two cufflinks. Might be leaking now. While out i checked the sail switch with tester, worked. Pulled out igniter and it was sparking. Gas is definitely coming through the line, and all other gas appliances work great. Original owner said it worked fine till one day it didn't and he said he never touched anything. My guess is somehow gas is not getting into combustion chamber. Does the board let it in? Put it back in kinda, and tried again same result. tried running fan with manual valve off then turning it on blah blah nothing nothing nothing nothing. It will only try to spark once. Thinking of pouring gas on it and lighting on fire maybe then it will produce some heat. Any ideas? thanks
 
Welcome to The RV Forum!

Check the furnace intake and exhaust tubes for blockage.  Insects are attracted to the smell of the mercaptin added to propane so you can smell a leak and will often build nests in the tubes.

Along the same lines, make sure the gas orifice isn't blocked.  Gas pressure is only about 0.4 PSI after the regulator so it doesn't take much to block the flow.  Use a brush to make sure the orifice is clear - don't jam a wire into it as it may change the size of the orifice.
 
My guess is the sail switch not operating under real life conditions. Try adding a piece of tape to the end of the sail switch to add more wind resistance. If that works, install a new sail switch.

BTDT
 
The gas valve may not be opening if the sail switch is good. As I recall, Suburban uses a dual valve, and both sections must open for gas to flow. The PC board does control the valve when it sees the sail switch close, so that's another possibility. Many RV repair shops have a board tester that can check that out. One quick test is sniff the exhaust port when the furnace is turned on and you hear the ignitor spark snapping. If you don't get a whiff of LP before the board locks out, the valve isn't opening.
 
92Coronado said:
Pulled the thing out of my 92 coronado, managed to kink the gas line and had to sweat weld a new piece  of copper with two cufflinks. Might be leaking now.
Click to expand...

I wouldn't do anything until you fix the leak.  You could have propane leaking into the basement and any type of ignition/spark will surely give you plenty of heat.
 
If the igniter sparks during the ignition cycle, the sail switch is engaging. There will be no power to the igniter circuit board unless the sail switch is satisfied.

If the fan runs, the igniter sparks and gas valve opens, the problem is almost surely poor air flow in/out of the burner chamber (combustion air). The furnace is very sensitive to air intake & exhaust flow to achieve a proper air/fuel mixture for ignition. Lou Schneider's advice is right on target.

For more help, please see my Library article on Furnace Troubleshooting at http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf
 
You've received some good advice above,but Rene's has been the best so far. :)
 
You must log in or register to reply here.

Latest posts

Members online

Total: 1,235 (members: 32, guests: 1,203)

Forum statistics

Threads
131,933
Posts
1,387,743
Members
137,684
Latest member
kstoybox
Back
Top Bottom