problems with furnace

[Bob in Mb]

The furnace should try to ignite three times , if it fails then should shut down . What do you mean by [ it is firing ] ? Just sparking or actually firing up ? If it does not light and the solenoid is opening then it does not have a gas supply [air in the line ] or bad line or regulator . If it lights and goes out - faulty flame sensor .

[sorceress]

Ok, it does not light, just sparks. Seems valve come on for a very short time. voltages are all over when this is happeneing. It does cycle three times. thanks Eric

[Bob in Mb]

You need to make sure that your valves open if they get proper voltage - disconnect leads and connect a direct power supply to the solenoids - you may want to use compressed air rather than propane for safety . If they do open but do not open when connected to the unit , then the problem is in your board . If they do not open under either case then the problem is the solenoids . Both items are readily available on E_Bay or Vintage Trailer Supplies .

[sorceress]

Thanks Bob, hooked up 12 volts independently, and can't hear any air going through the burners. should I pull it off the unit and try again, or just order a set of valves.thanks Eric

[sorceress]

OK I took the valve out, doesn't work. Took it apart and I can't find anything wrong with it . Eric

[steve dunham]

You can check the valve coil windings for continuity with an ohm meter -- Check the polarity on the coils versus the wiring -- Energies the valve coil with 12 V and touch a small screw driver to the valve stem ,you should feel magnetism -- Make sure the valve plunger works freely and there is no corrosion on the plunger and spring .If all else fails buy a new valve

[sorceress]

I tested everything, the solinoids pull the valves off the seat fine, the diaprame looks great, just won't release gas, can't figure why it won't work. checked ebay and they don't have a valve that looks like that. I'm concerned that the board is bad too because it won't hold the valves open for but a second. Maybe this thing is not worth fixing? thanks again.Eric

[Bob in Mb]

The valves should not stay open very long , just long enough to get a spark - if they stayed open longer the next time it sparked you would have an explosion . Also if the valves are opening you will not get a great gush of air through it - it is a very small oriface so a very small flow - try soapy water on the outlet see how much bubbling you get .

[sorceress]

OK Bob will do.thanks Eric

[Joe Romas]

Most but not all gas appliances in our trailers have a secondary regulator in their valves and the furnace does.
Could that regulator be out of adjustment

Also be careful when working around your control board, When I was working on quieting down the fan noise I killed it

My plan and it worked on the bench was using a PWM board controlled by a heat sensor have the fan speed follow the temperature inside the furnace.
It worked well starting slow and as the temperature went up so did the fan speed and the converse when the flame was shut off and the temperature went down.
The result was the furnace didn't come on and go off with a roar.
The experiment was a success but there was too much added to my liking

On my Suburban water heater the instructions are given on testing and adjusting the internal regulator no such luck with the furnace.

Joe

[Bob in Mb]

When you find your problem and a solution make sure you clean your flame sensor before you put everything back together . It will probably be your next problem .

[sorceress]

Hey I have a question, since they don't make a 12se anymore, and I can't find the valve for sale, will a nt16se fit in the same place, I think I have located a used working one. Thanks Eric P.S. shame to junk this one, it looks brand new.