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gene
gene, RV Mechanic
Category: RV
Satisfied Customers: 1100
Experience:  28 yrs exp in the industry
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Suburban: heats..the burner shuts off, the blower runs..wont run

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I have a suburban SF35 furnace, runs and lights and heats fine, however, after the burner shuts off, the blower runs continuously until I pul the fuse for a second, then it seems to reset and won't run again until the next heat cycle....any suggestions
Hi,
Here is a manual on the furnace,what is happening is the furnace is cycling off the high limit switch instead of the thermostat,the high limit is shutting off the burner before the thermostat opens and tells the furnace to shut off.The limit is effected by restricted ducts causing the limit to open and shut down the burner,fan continues to run because the thermostat is still calling for heat.Check all ducts,remove any kinks,restrictions and be sure all are open or not covered,if air flow is good out the ducts,then the high limit is weak and needs replaced.The high limit is behind the cover inside the coach at the furnace.
Customer: replied 6 years ago.
I have the furnace out of the coach and tried running it with no gas and just connecting the thermostat wires together, then separating them and waiting... the same thing happens, can hear the gas valve open, then when I disonnect the thermostat wires, the gas valve closes and the blower continues to run, for more than 5 minutes
If the motor wires are connected to the control board,the control board is what runs the fan to cool down the box before shutting down the blower,it is supposed to run a while to cool the box,can you hook a bottle to it and test it with lp?In the trailer,from what you said,the high limit is opening and keeping the blower running until you either turn the thermostat off or pull the fuse,this resets it and it will relight again.
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