Suburban SF-35VHQ Issues

[JRW8]

2023 Solitude 378MBS

Turn the furnace on and blower engages, blows cold for 30 seconds during the purge / pre-ignition cycle and cuts off.

Have checked / replaced both the sail switch and hi-limit switch and same symptoms.

I can manually engage the sail switch after switching to Heat Gas on the thermostat and the blower starts to which everything will fire up but once I let my finger off of the switch it falls back to it's original position and the unit essentially cuts off after a minute or two of run time.

Have checked all of the vents and there is no blockage, etc.

Am on 50a shore power, so no issues there.

Have checked propane, all is full, flow is fine.

I feel like for some reason the blower fan isn't producing enough output to engage the sail switch, but output when running for startup produces sufficient air inside coming through the vents so not sure.

Have a Dinosaur 50 PINS Plus board on order and waiting for it to come in to change next.

Completely stumped as this point-

Thoughts?

[howson]

2023 Solitude 378MBS ... Completely stumped as this point- Thoughts?

I've read similar symptom threads both here and on a "RV Technician Only" Google group I'm privy to monitor. In each case it was the blower motor. The motors are extremely hard to come by -- maybe because so many are failing? (Guess on my part.)

If you're still under warranty, call GD Customer Service. If you're willing to swap out the component yourself, they may send a replacement. (Remember--I'm just an owner like you.)

If the "quiet" version isn't available, consider the standard furnace as a replacement. (The "Q" in the model identifier designates it as the "quiet" version.)

Howard

[Jlawles2]

I wonder if the fan cages are getting inefficient due to dust build up on the fins.

If the OP is this far into it, checking those fan blades for buildup may not be that hard of a task.

[JRW8]

I wonder if the fan cages are getting inefficient due to dust build up on the fins.

If the OP is this far into it, checking those fan blades for buildup may not be that hard of a task.

Everything has been blown out with compressed air and found virtually no dust as the unit is only a few months old..

[howson]

Everything has been blown out with compressed air and found virtually no dust as the unit is only a few months old..

Do you have a clamp multimeter capable of measuring DC current? I'd be interested to know how many amps the motor is pulling.

This is an "advanced" test--not something the majority of owners could do even if they had the meter...but who knows...

Howard

[JRW8]

Do you have a clamp multimeter capable of measuring DC current? I'd be interested to know how many amps the motor is pulling.

This is an "advanced" test--not something the majority of owners could do even if they had the meter...but who knows...

Howard

Yes, I have Master's Degree in Engineering and know how to use a multimeter.

Tested this morning, with a reading around 6.34, which for this particular unit loaded should be in the 8.8 (+/- 0.6A at 12.00VDC.)

Have a replacement motor on it's way and will upgrade to the board with the Dinosaur board when replacing the motor this weekend since I'll have it all apart.

Should fire right up and hopefully be trouble free with the upgrades.

[TucsonJim]

Yes, I have Master's Degree in Engineering and know how to use a multimeter.

Tested this morning, with a reading around 6.34, which for this particular unit loaded should be in the 8.8 (+/- 0.6A at 12.00VDC.)

Have a replacement motor on it's way and will upgrade to the board with the Dinosaur board when replacing the motor this weekend since I'll have it all apart.

Should fire right up and hopefully be trouble free with the upgrades.

Great job. Welcome to the forum. We have quite a few engineers from various disciplines here.

Jim