ThomasLM

17 hours ago, Kirk W said:

That is a very common symptom and nearly always indicates that the ignition probe has failed. The same probe that supplies the spark to light the furnace also detects the heat of the burning propane. If it does not send a signal back to the circuit board that it detects the heat from the burning propane, it will try 2 more times and then go into safety lockout. If you turn the furnace off and after a brief pause turn it back on it will repeat that same sequence. Over the many years that I have had an RV and also helped others repair their RV furnaces, I have probably seen that issue about 20 times and nearly all of them were the ignition probe.

If you do not have one, you can download a copy of the Suburban Service Manual from this link. On page 7 of that manual the troubleshooting guide addresses your symptoms. 

Thank you that was a very detailed reply and appreciate you taking the time to answer. I will see about getting the part. 

I have a Suburban SF-25F RV Furnace that is not working properly. I followed the instructions to start and here is what it does:

- Blower comes on

- You can hear the igniter click

-then you can feel and hear the burner blowing hot exhaust out

- however it only lasts about 20 seconds then turns off and

- then cycles two more times doing the same thing

- then after the third attempt the blower runs for about 5 minutes and turns off.

What have I done:

- Removed the furnace and checked the "sail switch" (after isolating it I held multimeter to it and move the switch up and down, continuity when on and off as I moved the switch.

- Then I isolated the High Temp switch and had continuity thru it.

- then I disconnected and reconnected all wires to ensure goo connection. 

BUT IT STILL DOES THE SAME THING.  Any ideas