Furnace Problem 2002 RSB

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BornFree_n_Now
Posts: 168
Joined: Sat Aug 13, 2005 9:28 pm

Furnace Problem 2002 RSB

Post by BornFree_n_Now »

Getting chilly in Oregon ~ Furnace has ceased to start ~ thermostat is functioning (clicks inside when asking for heat AND clicks at furnace indicating it has received the request).

The next step should be for the fan to start, which is what is not happening. Motor turns freely and what connections I can reach from outside seem well connected.

We are fully loaded and living in RV during house construction, so am looking for an easy way to further diagnose issue (hopefully w/o having to attempt the removal of the unit).

Any suggestions will be appreciated.
Larry & Sharon
2002 26' RSB
Suzuki X90 4x4 Toad
Sab & Ann
Posts: 49
Joined: Tue Sep 13, 2005 7:12 pm

Furnace Problem 2002 RSB

Post by Sab & Ann »

Take the cover off the themostat and clean the contacts with a cleaner or close the contacts between plain copy paper and slide it back and forth. You also can jumper the contacts and wait for the fan to activate. The fan must activate before the furnace will turn on.
You can use the heat system that comes with the HVAC unit. And/or buy a ceramic heater for about $30.
2000 RB, E450
Roger
Posts: 125
Joined: Sat Oct 18, 2008 10:19 pm

Post by Roger »

These things use a circuit board that controls the furnace functions/timing.
They seem to be a rather high failure rate item.

Good luck, Roger
1999 24RB
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BornFree_n_Now
Posts: 168
Joined: Sat Aug 13, 2005 9:28 pm

Post by BornFree_n_Now »

Thanks for both responses.

I changed our thermostat years ago to a Hunter digital which really has worked quite well, so I really have no contacts to clean, any longer.

Have been using our AC unit's heat strip and a great little ceramic heater, and either, or both, will keep us quite warm.

Really need the security of being able to stay warm during power outages, which do happen in our neck of the woods, and hence our concern about fixing the issue as soon as possible.

On the circuit board front, I feared that that may be the cause, in that it is a fairly dumb circuit, only having only two control wires going in (can't control the fan independently).

I also changed out the thermostat and both exhibit the same progression ~ click at thermostat, click at control board, and then no ensuing motor start.

Another important fact is that this happened several days ago, at which time, I thought I had found the culprit, in that, when I removed the 15 amp circuit fuse, and then replaced it, the system started to work again, which it did for approximately 2 days, when it again failed to start.

Tried the fuse again, and then measured across the two sides of fuse holder with an ohm meter and found the circuit was complete, so figured it was an intermittent failure somewhere else in the circuit.

Will try Kim on Monday, and then the folks at Suburban to see what they have to offer ~

Have vaguely heard of issues with "boards" and noticed that even on eBay they are going for about $100.

Thanks again, for your responses, and remain interested in hearing any others.
Larry & Sharon
2002 26' RSB
Suzuki X90 4x4 Toad
Roger
Posts: 125
Joined: Sat Oct 18, 2008 10:19 pm

Post by Roger »

Another important fact is that this happened several days ago, at which time, I thought I had found the culprit, in that, when I removed the 15 amp circuit fuse, and then replaced it, the system started to work again, which it did for approximately 2 days, when it again failed to start.

Tried the fuse again, and then measured across the two sides of fuse holder with an ohm meter and found the circuit was complete, so figured it was an intermittent failure somewhere else in the circuit.

Did you perchance measure the voltage going into the furnance? I seem to remember that low voltage can cause this problem. Could be a poor ground connection.

Good luck, Roger
1999 24RB
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Eric Sandstrom
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Joined: Fri Dec 23, 2005 8:07 am

Post by Eric Sandstrom »

Comment on furnace voltage.

http://www.rvdoctor.com/2002/02/rv-heat ... nance.html

"When dry camping, the minimum voltage requirement for most all 12-volt DC forced air furnaces is 10.5-volts DC, measured at the furnace. Conversely, when plugged into shore power, running off the converter output, excessively higher than normal DC voltages (above 13.5-volts DC), can create their own palette of problems for the delicate components found on some circuit boards."
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Eric Sandstrom
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Joined: Fri Dec 23, 2005 8:07 am

Post by Eric Sandstrom »

Forgot to note that our 2002 coach has had refrigerator issues at below 11.5 volts as the safety interlocks kick in to prevent the propane valve from opening and therefore the furnace from operating/coming on.
oliverpsmile
Posts: 271
Joined: Thu Dec 18, 2008 2:46 pm

Post by oliverpsmile »

Look for a local (on the circuit board or around it) blown-up fuse. It is a common practice local control boards to have built-in over-current protection (fuse or may be small circuit breaker).

There are several reasons for the fuse(s) to blow-up.

- Short in the wiring (burnt wires etc) - less likely
- Short in the fan motor itself (rotates freely therefore no extreme counter torque).
- Short in the starting relay
1. In the coil (check with ohm meter it should be more than 500 ohms)
2. Main contacts (DC creates considerable amount of arcing).

Try to connect the fan motor directly to 12 VDC source and continue backwards (relay, local fuse, wiring etc.)

Good luck and keep warm!
Oliver P Smile
2005 26ft RSB
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bbwolf
Posts: 163
Joined: Sun Apr 25, 2010 10:07 am

Post by bbwolf »

This is not a solution to getting your heater working but instead an alternate heat source. As long as you have 110v connection, just use one of those small electric space heaters. It is amazing how well it works.
Alan and Jeannie Wolfe
2014 Born Free Freedom
allanmullaly

Post by allanmullaly »

I suggest to repair this furnace as I think it is not a big issue. First call the expert to repair it.
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