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RV furnace won't light? Atwood model 8525 IV DCLP. What would be the problem? The furnace starts with the blower, then I can smell gas when something clicks outside, but it does not light and burn. What could be wrong?
The most common causes of this are a defective control board or low LP pressure at the regulator if you have good voltage to the unit. In any DC appliance, you need to be sure you have adequate voltage or it won't work properly. In the case of a furnace it won't develop enough fan speed to engage the sail switch and won't ignite. You can take your regulator off and into a shop to be tested if that is more convenient. Some are not adjustable and would need to be replaced. If you have an outside inspection panel on your coach you can take it off by removing the 4 screws at the corners if you have that style or just unscrewing the latch screw if that is what you have. Once inside you can take the control board out which is located on the L/H side. It just unplugs. If you don't have the outside access panel you will have to remove the furnace from the inside. Some coaches use this style install. Any RV shop can test this for you. If you need a new one I would go with one by Dinosaur Electronics as they are far superior to the OEM boards and have an outstanding warranty. Most shops carry them. Go HERE for a copy of the Service Manual which covers this unit. It outlines the various trouble shooting steps that you can do in addition to what I have told you. Get back to me if you need more help with this.
You didn't tell me about the flashing red light? There is a light on the circuit board that is flashing 3 times and then pauses for a little bit and then flashes 3 times. The note on the blower housing says when the light flashes 3 times then there is ignition lockout fault? What do I need to do to repair that?
That just resets once you turn it off, that is an “ignition lockout” and just happens when it won’t ignite. This can happen for any number of reasons as stated before. Always turn the stove top on and let the pressure equalize if the gas has been off for a time. So, just to be clear, that isn’t a repair issue necessarily. It can be if the flame sense on the board is bad or the igniter goes out. Any number of things can cause this. One of the reasons I give a manual out so I don’t have to repeat so many things. Do you have the outside access door or not? Sounds like you do or you usually can’t see the board. Let me know if you need more help after you check the LP pressure and the board. Be sure you have good voltage to the furnace. A digital multimeter is very helpful in this. About $15-$35 at most automotive or hardware stores.
I have 13.58 volts at the furnace. the gas at the stove is good, I lit the stove and let it burn for a while. There are 2 furnaces in this Motorhome, both are the same models. I took the board out of one and put it in the other, there was on difference in the operation of the furnace. You can smell gas when the furnace cycles, but will not light? What do I need to replace or clean?
Does it have an insect screen on the exhaust? Perhaps the wasps got into it and plugged up one of the chambers so it won't breathe right, this happens quite frequently. When you smell LP and it won't ignite that is usually a sign of this. Sometimes they get into the combustion wheel area and sometimes clear down inside the heat exchanger. It can be a pain trying to blow all that out of the furnace and you can bang on the heat exchanger (gently) with a rubber mallet to see if you can dislodge them. Take the cover off over the igniter and see if that is right in there. Sometimes you can shine a flashlight into the exhaust and see them down in the pipe and use a shop vac to get them out and a long piece of clothes hanger. Let me know what you find.
There are no wasps in the furnace. The furnace is clean. I think I will have to take to repair shop, I don't seem to be getting any answers as to what the problem is?
That manual link gives you all the things that can cause this problem. Follow that with your test light and see what component isn't working. Take your test light and see if there is power to the gas valve when the board goes into ignition. If there is and it still won't fire then the valve may be defective or "stuck” it can also be a bad igniter that has the end burned off. You have to remove the furnace to test that. Do the easy things you can reach and if those don't resolve this then I would do the shop thing. Bench testing is the way to resolve all these issues. You also won't know if the brushes are about worn out and causing this. Lots of things can do this to a furnace. Let me know if you want to proceed any further.
I replaced the igniter and the furnace works fine.
That would do it as I said, there are a number of components that can do this.