The RV shop cleaned the heat exchanger, I installed a screen over the air inlet/outlet on the furnace heat exchanger, and all has worked well since. With the cold, heavy air, the furnace fan couldn't force enough air through the restricted heat exchanger to open the sail switch. Apparently, when the ambient temps were warmer and the air lighter, the fan could push enough air through the heat exchanger to activate the sail switch. The previous owner of our motorhome must have stored it in an area with lots of dirt dobbers, since they had build their mud nests in many concealed places on the coach. They found that the air passage through the heat exchanger was clogged with dirt dobber nests. It was too cold for me to work on the furnace, so I took it to an RV service shop near us. The furnace went through the same lighting sequence you described. The furnace worked fine when the temps were warmer, but when they approached freezing, the furnace would not light. I had a similar problem with my motorhome during the first winter I had it.
Great stuff for troubleshooting cold related problems. It cools circuits and components quickly. Tell the shop to get a can of "circuit freeze" or something similar at their local electronic part store. Most solids contract as they get colder and poor solder joints and/or crimp connections sometimes open or increase resistance to upset the logic circuits on the board. If that is OK, you will require volt and ohm testing of the board, switches, and solenoid. It that doesn't work, you need to manometer the LPG system.
On some solenoids you will hear it "click" to the open position. The control board opens this valve as it begins the spark sequence - lighting the burner in normal operation.Īssuming you have good DC voltage, the next time it sparks but no flame, warm the fuel line solenoid with a heat gun or hair dryer until it is fairly warm to the touch. What I have experienced in cold weather are sticking solenoid LPG vapor valves. If the flame does not look right, then I agree you need a manometer check. You should have a mostly blue flame with a small blue cone within the larger flame. You may have a regulator issue when very cold and Bill's suggestion with the burner is good. If no current from the flame sensor, the board locks out. When it does spark, it will try three times.
If the sail switch is defective, the furnace's control board's starting sequence will not get to the spark function.
0 kommentar(er)
