I tried running the furnace multiple times without ignition. Where should I begin my troubleshooting? Propane is on. The fan runs, sounds like something's trying to ignite. I looked behind the outside panel but there's not much exposed to see if I'm actually getting a spark.
Does the stove light? Normal flame height?
I assume it's a Atwood propane furnace. If so turn it on and go outside next to the furnace and listen to see if it's sparking. If not I would suspect the fan switch.
see ya
ken
Stove lights with normal height. Is there anyway to visualize the igniter?fan seems to run. Something sounding like a secondary fan switches on after about 10 seconds. Runs another few cycles before shutting down.
Yes, critical diagnostic point:
Easiest to determine from outside standing next to the furnace/someone else turning it on:
Fan starts.
Then, do you hear any clicking of the igniter? The solid "click" of the propane valve opening? Smell propane?
Basically, we need to know how far in to the run cycle it gets before failing.
Ok.. so I need to replace the motor.. anybody have a sourse?
John,
What diagnostic lead you to that conclusion?
There was a sparking sequence without the metallic sound . I don't smell propane. It goes through 3
20 second cycles before quitting.
You need to check for 12 volts to the gas valve while it is sparking, if you have 12 volts, will need to disassemble the orfice assembly and remove the orfice, it screws in and see if it may be plugged with nats, have seen that many times
You must have air flow, not just the fan running, there should be a limit switch on the air flow damper, without enough air flow..... gas valve wont turn on. We discovered this the hard way one night when temps hit the upper 20's.
You are correct, the SAIL SWITCH must close for the PC board to open the propane valve. But, since the igniter functions the same way, the sail switch IS closing.
So checking for power to the gas valve will tell if the valve is bad or if there is problem in the PC board or wiring from it to the gas valve.
I would start by disconnecting and reconnecting the control board to be sure all those contacts are good.
JD
Google to the rescue - first hit:
(This document incorporates all the above mentioned excellent suggestions, in a logical sequence, with photos)
http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf
For a motor squeal, I would start by oiling the motor bushings. Yes, it is not easy to do, but some light machine oil on a long blade screwdriver or similar on each end of the shaft will allow the oil to wick into the bushing area.
If it doesn't work, then yes, you will need to replace the motor.
Also, verify that the fans are not hitting the housing and that there is no mud dubber nest upsetting fan balance.
Beamalarm.com (RV Technical Help) offers some excellent advice:
Troubleshooting RV Furnace Problems (http://www.beamalarm.com/Documents/troubleshooting_rv_furnace_problems.html)
Check, check.. oiled last winter.. then it's march.. squeel.. breaker.
Since its apart.. want to replace motor.. is there a direct replacement or.. automotive supply..
Barry's site good.. great but I couldn't find motor replacement Chuck.. remember I'm seeing impaired.so I miss a lot..
Well, after all the advice you have gotten I am almost afraid to say this. My bedroom furnace is hard to light after it has been sitting without operation for a long time. I seldom use my furnaces (if it's cold outside, I am south bound). But........if I cycle the on/off switch up to 50 times (sometimes less). it finally ignites and stays lit. Then after it runs a few cycles it's good again.
You have to listen to the clicks of the igniter. It will click once to ignite and if it doesn't fire there will be a couple of other clicks in succession immediatly. After the secondary clicks I turn off the switch and back on again and keep doing this until I hear the roar of the flame.
Don't know why but never had to replace anything.
We bought a motor for our furnace from an RV dealer in Billings, MT. Temperatures were 10F and one of our two furnaces failed with the dreaded squeal and eventual failure to turn fast enough to operate properly. The motors are very specific to the particular furnace you have. If you open the plastic cover, you should be able to read the label on the fan. The dealer recommended replacement of the sail switch while the unit was apart.
A few years ago, we had a furnace that would go through the entire startup sequence, but would not light. I concluded that the sequence was complete because I could hear the spark and smell a bit of propane, but there was no ignition. The problem was damage to the flame grid caused by dauber deposits and overheating of the grid. FOT fixed the furnace and I added dauber screens to the intake/exhaust ports.
Ask, and you shall receive.
1. Go to this link, read through it (lots of good info), find your furnace model number. Go to the parts section at the end, look up motor number:
http://bryantrv.com/docs2/docs/hflamefurn04.pdf
2. Google the motor number for possible replacements. If you have the popular 85-IV 16 or 20 furnace, this motor will probably work:
Amazon.com: Atwood 37696 Hydro Flame Replacement Motor: Automotive (http://www.amazon.com/Atwood-37696-Hydro-Flame-Replacement/dp/B00CLSWCH8)