Suburban Furnace

[DaveRVman]

I thought I had a bad controller on my Suburban furnace. So I replaced it with a dinosaur electronics board.

Still no exact fix. However it starts by cycling the blower on for 1 second then turning off. Stays off for a couple minutes. Then it turns back on for 1 second, then off wait for a couple minutes.

Then it really starts to cycle faster and faster. 1-2 seconds on, 2 seconds off, 1-2 seconds on, 2 seconds off... Over and over again. for a long while this happens until I lose patience.

I am positive I have the new controller board on correctly.
I am positive my propane is on.

Wondering if it is my valve or striker. ?? Any pointers?

Is there a good way to test a striker?

[enblethen]

Sail switch could be good, but low voltage to motor and fan can cause it to drop out.
OP never responded to my earlier questions.

[Huntindog]

DaveRVman wrote:
Sail switch as good continuity when tested....

The sail switch is the most common part to fail. It is also the cheapest.

I once had one that tested good , but was really bad. When I finally figured out that it was failing intermittantly, I took it apart, and the insides were toast....
I now carry a spare. They can be had on ebay for about 7.00. If you are that far into it, just put a new one in while you are there.

[DaveRVman]

Sail switch as good continuity when tested....

[ktmrfs]

DaveRVman wrote:
I thought I had a bad controller on my Suburban furnace. So I replaced it with a dinosaur electronics board.

Still no exact fix. However it starts by cycling the blower on for 1 second then turning off. Stays off for a couple minutes. Then it turns back on for 1 second, then off wait for a couple minutes.

Then it really starts to cycle faster and faster. 1-2 seconds on, 2 seconds off, 1-2 seconds on, 2 seconds off... Over and over again. for a long while this happens until I lose patience.

I am positive I have the new controller board on correctly.
I am positive my propane is on.

Wondering if it is my valve or striker. ?? Any pointers?

Is there a good way to test a striker?

fan should come on for about 20 seconds before the board signals for ignition. Now on some dinasour boards there are two settings, instant ignition or 20 second wait. IIRC the default is the 20 second delay. Make sure you have it set for the delay. If it is set that way and fan doesn't run for 20 seconds or so before ignition, something is amiss with the system, possibly the sail switch not connecting, thus shutting everything off.

[_1nobby]

DaveRVman wrote:

I am positive my propane is on.

I always have trouble getting the furnace to cycle on the first time. I've learned that running my stove top burners gets propane into the lines faster than the furnace ever could.

[enblethen]

I would check the porcelain portion of the ignitor for cracks. Check the high voltage lead for signs of arcing to ground.
Fan should run for 15-20 seconds before the ignitor comes on.
Are you running off battery or shore power? Low battery could cause fan to slow down enough for sail switch to drop out ending cycle.
What model of Suburban furnace?