No heat
Was using the furnace tonite but noticed the fan kept running but the air from the vents were cool. Swapped tanks but didnt make a difference. Got propane at the cook stove. What should i look for?...
Forum Discussion
Check the opening on the outside of the camper and the rest of the intake channel for mud dauber's nests..They frequently get in there and build nests in the exhaust or intake, sometimes both, which restricts the draft and exhaust of the furnace. If they have built in the intake, it can't pull in enough air for everything to work properly.
Here are some other things to consider.
Fan Runs but No Heat from Ducts
This is a classic condition with several possible causes, most of which should be obvious after
reading the Operational Overview.
1. The Sail Switch is not closing, so no power to the rest of the furnace. This may be because of
a defective switch or because the fan is turning too slowly to push the sail enough to fully
close the switch. A slow motor may result from low voltage at the motor (check voltage at
batteries and at the fan) or a motor that is simply not turning well due to dirt or corrosion. A
blockage of the Return Air Intake can also cause a lack of air flow against the Sail.
2. The High Limit Switch has failed and is not closed, so no power reaches the Controller
Circuit Board and hence no ignition. Check for 12+ volts leaving the switch and/or at the
terminal on the controller.
3. The Control Circuit Board is failing and either does not open the Gas valve or does not
trigger the Igniter. Check for 12V to the gas valve during the opening cycle.
4. The Gas Valve fails to open, so no propane in the burner. Could be a bad valve or simply no
12v power is reaching the valve (check voltage).
5. The Gas Valve is open but no propane flows. Possible causes include no propane or low
propane pressure (less than 11 water column inches). Low or no propane can be caused by a
clogged line or main propane regulator. Check other propane appliances for proper operation.
6. The Igniter fails to spark (or in a non-DSI furnace, the Pilot Light is not on). Could be a
defective Igniter or no 12v power is reaching it. It is also possible the gap at the ends of the
Igniter electrodes is too great (or that they are shorted together).
7. Igniter does not confirm that ignition was successful (no flame is sensed), so the
Control/Ignition board has shut down (lock-out)
8. Propane and spark are present but the burner doesn’t light. This can occur if the Combustion
Air Intake is clogged and there is insufficient air flow through the combustion chamber.
9. Loose or corroded connections in any of the above components
Here are some other things to consider.
Fan Runs but No Heat from Ducts
This is a classic condition with several possible causes, most of which should be obvious after
reading the Operational Overview.
1. The Sail Switch is not closing, so no power to the rest of the furnace. This may be because of
a defective switch or because the fan is turning too slowly to push the sail enough to fully
close the switch. A slow motor may result from low voltage at the motor (check voltage at
batteries and at the fan) or a motor that is simply not turning well due to dirt or corrosion. A
blockage of the Return Air Intake can also cause a lack of air flow against the Sail.
2. The High Limit Switch has failed and is not closed, so no power reaches the Controller
Circuit Board and hence no ignition. Check for 12+ volts leaving the switch and/or at the
terminal on the controller.
3. The Control Circuit Board is failing and either does not open the Gas valve or does not
trigger the Igniter. Check for 12V to the gas valve during the opening cycle.
4. The Gas Valve fails to open, so no propane in the burner. Could be a bad valve or simply no
12v power is reaching the valve (check voltage).
5. The Gas Valve is open but no propane flows. Possible causes include no propane or low
propane pressure (less than 11 water column inches). Low or no propane can be caused by a
clogged line or main propane regulator. Check other propane appliances for proper operation.
6. The Igniter fails to spark (or in a non-DSI furnace, the Pilot Light is not on). Could be a
defective Igniter or no 12v power is reaching it. It is also possible the gap at the ends of the
Igniter electrodes is too great (or that they are shorted together).
7. Igniter does not confirm that ignition was successful (no flame is sensed), so the
Control/Ignition board has shut down (lock-out)
8. Propane and spark are present but the burner doesn’t light. This can occur if the Combustion
Air Intake is clogged and there is insufficient air flow through the combustion chamber.
9. Loose or corroded connections in any of the above components
