Suburban SF Series Furnace – Random No Response ( No Blower Running) if you’re having issues read on.
(I had chat gpt clean this up for me.)
I have learned from other VL owners that sometimes the spyder system will glitch out. For example someone posted that when the temperature setting is met, the furnace will shut down. However, the spyder touch screen will still show the red flame icon: which means the system is still calling for heat even though the furnace was stopped by the spyder system. They said if they turned off the furnace and turned it back on via the touch screen, the red flame icon went away. They stated that when this occurs the furnace would not restart automictically when it dropped below the set point. This is something you may not notice unless you are observant. It is something to check if you are having issues with the furnace not restarting when it should. They said rebooting via battery disconnect resolved the issue for awhile. If yours is doing this I would reach out to spyder tech support. 1-866-919-9092 for help. I have not saw any follow up on what may be causing this issue.
About me: I went to welding school and did that long enough to hate it. I joined a Union and became an Electrical Mechanical Millwright by trade. I am currently employed as an Electrical Maintenance Planner a Utility in Indiana. I am not a certified RV Tech. I did have a handyman side business for several years.
I do 99% of my RV Repairs and I also do side work for my friends. (I say 99% because I have a warranty and I have used it) I did my own comprehensive Pre- purchase inspection. I wrote up a report with photos and had the dealer fix all items. I made them do full hook up during final walk through. I again tested every function thoroughly. Everything was working. In Nov 2024 I bring the Vilano home and a few days later the furnace wouldn’t start. I never had the Spyder system and figured I would reboot by cycling battery disconnect. That worked. I figured it was probably just a glitch from unplugging from shore power at walk through. It wasn’t. The problem slowly became more prevalent.
Suburban Furnace Model: SF-35VHFQ
RV: 2022 Vilano 320GK
Symptom:
The furnace would randomly fail to respond when the thermostat called for heat. No blower, it did nothing. Cycling the battery disconnect would usually reset it and allow it to run.
This issue first appeared in November 2024 and occurred intermittently upon use. In November 2025 (Thanksgiving weekend) I replaced the furnace control board, which appeared to resolve the problem—temporarily.
In January 2026, the furnace again failed to respond to a call for heat. At that point, I decided to perform a full, step-by-step diagnosis with no assumptions.
Step-by-Step Troubleshooting
- Power Loss / Blown Fuse
• Checked the G6 panel: no blown fuses
• Verified voltage at the furnace board plug (red wire): 13V present
Power to the furnace confirmed
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- Ground Integrity
• Tested the yellow ground wire at the board plug.
•Verified solid continuity between the ground wire and the furnace case.
Ground confirmed good
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- Thermostat / Call for Heat Signal
The Vilano 320GK has three wires going to the furnace board plug:
• Red: +12V power from coach
• Yellow: Negative Ground from coach
• Blue: Thermostat from spyder +12V when calling for heat.
• Verified using a Fluke multi-meter
• Spyder thermostat sent ~13V on the blue wire when calling for heat
Thermostat and control wiring working correctly power and ground were good.
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- Control Board Functionality
Although the board was recently replaced, I verified its operation.
Normal Board Logic:
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Board has +12V power and ground
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Thermostat sends +12V on the blue wire (call for heat)
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Board sends that power to:
• Over-temperature switch: if its ok it passes power to the sail switch.
• Sail switch is normally open with blower off
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Since the sail switch is open, voltage does not return to the board. That’s good and next:
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Board starts the blower
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Airflow lifts sail switch, closing the circuit and the Voltage returns to the board.
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Board sees the “proven circuit” and continues purge run. Then ignition starts and opening of the gas valve.
If the sail switch were stuck closed, voltage would return immediately to the board and the blower would not start because the board knows the sail switch is stuck or bypassed and the safety test fails. Resulting is the no response symptom I was getting But that wasn’t my problem. My system was working as it should and the blower should have been running. To prove it I lifted the sail switch. Power went to the board.
Test Performed:
• Manually lifted the sail switch to close it sent power to the board.
• Result: igniter clicked and gas valve energized and opened (gas supply off)
Board logic confirmed functional
Sail switch and Over Temp limit circuit, igniter and gas valve functional.
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Because everything’s proven up to here I moved on.
- Blower Motor Testing
• Verified 13V present at the motor red lead
• Verified solid ground between black motor lead and the furnace case.
• Confirmed 13V across red and black motor leads (probed wires).
• Motor spun freely by hand but would not run.
Final Motor Test:
• Disconnected motor leads from board and case ground.
• Measured resistance across motor windings
• Meter read: OL (open loop)
A healthy motor should read approximately 1-3 ohms or at a minimum when the meter is set to continuity it should beep.
My Blower was OL = Blower motor has internal failure..
Blower motor has internal failure.
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Final Diagnosis
Failed blower motor with open windings or stuck brush. Something inside is causing intermittent no-response behavior whenever this happens. Apparently it finally failed completely.
This explains:
• Random no responses
• Temporary recovery after power cycling the big jolt of
Power made it work.
• Eventual total failure.
A replacement aftermarket motor has been ordered.
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What I Learned from researching/ Advice for Others
The Suburban SF series furnaces have been installed across multiple RV brands, and there are numerous reports of early and repeated blower motor failures, including brand-new rigs and first time use. The previous owner of my Vilano never used the furnace in the 2 years he owned it. They were snowbirds in the keys and warm weather only campers.
Before replacing:
• Control boards
• Sail switches
• Limit switches
Verify the basics with a meter.
If the motor has power and ground but reads OL across the windings, it’s bad—even if it spins freely.
Note: As these motors start to fail they can struggle to get up to speed and do not move enough air to close the sail switch or struggle to keep the switch closed. This can show up as the blower is running but fails to ignite and shuts off then the goes through the sequence again eventually locking out. Or its running but starts acting strange like when its running out of gas because the sail switch opens and closes rapidly
A proper diagnosis can be done in 30 minutes or less and may save you significant time and money.
Parts:
If you need a board. I recommend Dinosaur Electronics. It has a 3 year warranty and is a universal board. It is plug and play on this furnace. It is around 100.00. You can purchase here and no you do not need to be a Rv Tech. I recommend this site because Amazon has vendors selling fakes labeled as Dinosaur Electronics.
I ordered my motor from
They have a wide array of RV parts including The over temp switch, sail switch etc. They will verify your model number making sure you order the correct part. My motor was $99.00 with free shipping. I went with aftermarket because Suburban is using the cheapest they can find obviously it failed early.
@RyanB Here is my longest post. lol Feel free to move it to what ever forum is best.
