Suburban Furnace Problems

[Elkrun]

I have a Cedar Creek 36 CKTS with a Suburban SF-42Q furnace. It worked properly until we had a nearby lightening strike and the motor would just run continuously. I took it to the dealer they advised it was the control board which was replaced. When I picked it up it seemed to run properly. However, we went out recently and I found it would run for 3-5 minutes then the burner go out and unit would try to restart three times before shutting down. It would actually fire each of the three retries but quickly shut off after 3-5 seconds. I removed the heater and checked the limit switch. It was closed, as it should be. Obviously, the sail switch was working properly since the start sequence always works. The burn chamber looks like new with no obstructions. Since it does initially start and run for some time, it must detect the flames' presence. It seems that the unit works fine, then just runs out of propane and tries the restart sequence. I'm stumped, I can only think it is either the regulator (all other propane appliances operate properly) or there is something wrong with the flame detector part of the process. Any help would be appreciated.

 

[Bama Rambler]

The first thing to do is unplug and replug the connectors on the control board. A lot of time they build up a little corrosion and the flame sense doesn't work correctly.

The next thing is to light several burners on the stove and then start the furnace and see if the stove burner flames remain constant.

 

[Elkrun]

I'll try your suggestions and see what happens. I'll let you know and thanks for the input.

 

[Elkrun]

Bama Rambler - I tried your suggestions to no avail. Same old three short ignitions, then it shuts down. I'm going to hook another regulator at the furnace inlet to see if that eliminates the problem. It would be nice if was just the regulator.

 

[YoungKopernik]

If the rest of your gas appliances are working I don't think its your regulator.
Flame sensor is more likely and ,as mentioned on the post next to yours, they can be cleaned lightly with some emery cloth. You can also test them with a multimeter, the standard is to put the meter in series and check for mili-amps but(its been a long time) I think if you pull it out you can check for mili-volts dc by connecting meters lead to wire and other to its bracket/ground then put it in a flame(stove).
If flame sensor is working I would check the gas solenoid
love campers
John

 

[Elkrun]

Thanks John, I did try another regulator at the furnace inlet but the results were the same. I'm not sure where the flame sensor is. However, I just took the cover off the burn chamber, which was very clean. When I just pushed slightly on the electrode it snapped off almost like it was crystalized. Maybe this is where the problem was. I'm going to take the furnace over to the dealership have the electrode replaced and see if it will operate properly then.

 

[Elkrun]

Well I've just about run out of options. I replaced the igniter electrode and positioned it as instructed(3/16" from the front of the lance and 1/8" above the center of the burner. Still get three short ignitions then a shut down. Obviously, the unit is not sensing the flame. The last resort is the electronic module which was replaced by the dealer. As far as I know, there is no way to test the board to verify the sensor portion is working.

 

[KyDan]

IF the flame is full size up until it shuts down it's not the regulator.
Sounds like classic bad board to me. (been there had that....)

I replaced mine with a dino board and never had any more problems.

 

[Elkrun]

Dan, flame is good and I since I replaced the electrode it's probably not that. So, I just ordered a new 3rd generation replacement board which carries a 3yr warranty. Hopefully that will solve the problem. Thanks

 

[Elkrun]

To all who made suggestions....thank you. I received the new board today and replaced the one installed by the dealership and the system works properly. Now I will try to get the dealership to refund the cost of the board they installed. Since they tested it and said it was good, I feel it is their responsibility. We shall see.