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guy99 · 03-02-2007, 09:47 AM

Hi all, we have a suburban furnace with electronic ignition. Until this morning it was working fine. This morning the blower works (blows cold air) but apparently the burner is not lighting - there is no heat either from the vents or outside at the vent/intake.

Any suggestions about what has failed?

I have had a little problem with the thermostat but I assume that if the blower is running, the thermostat is functioning (the thermostat has 2 wires to it).

janetbjt · 03-02-2007, 10:31 AM

when mine did that, the propane tank was empty and the blower would not go off, so unplugged power and switched tanks, then plugged back in and all worked fine. hope your fix is that easy (well...easy after i figured it out!)

guy99 · 03-02-2007, 10:34 AM

Alas, we have propane.

balrgn · 03-02-2007, 10:45 AM

On occasion, in my Argosy 20' Class A, I have had to turn the thermostat down a couple time then back up a few minutes later to get it to ignite.

This the first time in a while you have turned up the thermostat?

Alumi-Naught · 03-02-2007, 10:52 AM

check your voltage at the furnace. If the voltage is loe the fan will not spin fast enough and the sail switch will not engage.

Mark

eubank · 03-02-2007, 11:16 AM

Sail switches also fail, especially in somewhat dustier environments, and usually result in just the kind of symtom that you describe. Sail switches are relatively cheap to buy, but somewhat more difficult to install. What we've found is that the old sail switch can generally just be blown out well with compressed air and expected to live until the next time around. (Our new spare sail switch has been sitting in its original box now for several years!)

Lynn

Jim Clark · 03-02-2007, 11:52 AM

Quote:

Originally Posted by guy99

Hi all, we have a suburban furnace with electronic ignition. Until this morning it was working fine. This morning the blower works (blows cold air) but apparently the burner is not lighting - there is no heat either from the vents or outside at the vent/intake.

Any suggestions about what has failed?

I have had a little problem with the thermostat but I assume that if the blower is running, the thermostat is functioning (the thermostat has 2 wires to it).

Consider yourself lucky, summer will be here soon and you will want the cool air it is providing.

Thanks Jim

guy99 · 03-02-2007, 12:54 PM

Quote:

Originally Posted by Jim Clark

Consider yourself lucky, summer will be here soon and you will want the cool air it is providing.

Thanks Jim

Boy, wouldn't it be nice if it worked that way

TomW · 03-02-2007, 02:00 PM

Quote:

Originally Posted by guy99

Alas, we have propane.

I wonder if it is there & not getting lit. In an unusal move for me, I will jump right to the punch line:

Start up the furnace like you normally do, and step outside to the furnace vent. Do you smell anything other than cold air?

Tom

guy99 · 03-02-2007, 02:21 PM

Quote:

Originally Posted by TomW

I wonder if it is there & not getting lit. In an unusal move for me, I will jump right to the punch line:

Start up the furnace like you normally do, and step outside to the furnace vent. Do you smell anything other than cold air?

Tom

Don't smell any propane.

TomW · 03-02-2007, 02:30 PM

Quote:

Originally Posted by guy99

Don't smell any propane.

And this was from the outside vent?

Tom

overlander63 · 03-02-2007, 02:40 PM

Now, for MY stupid question, did you turn the propane on before trying to run the furnace?

TomW · 03-02-2007, 02:40 PM

Quote:

Originally Posted by guy99

Hi all, we have a suburban furnace with electronic ignition...

Do you hear the electronic ignition "clicking"

Tom

guy99 · 03-02-2007, 03:19 PM

Quote:

Originally Posted by TomW

And this was from the outside vent?

Tom

Yes.

guy99 · 03-02-2007, 03:22 PM

Quote:

Originally Posted by overlander63

Now, for MY stupid question, did you turn the propane on before trying to run the furnace?

If you mean at the tank, yes. Stove works, gas hot water heater work. The furnace worked fine last night but this morning it started blowing cold air.

guy99 · 03-02-2007, 03:24 PM

Quote:

Originally Posted by TomW

Do you hear the electronic ignition "clicking"

Tom

No, I don't hear any clicking but the blower is running so I'm not sure I could hear a soft click.

guy99 · 03-02-2007, 04:03 PM

RV tech just left. (Since we need to live in the rig until next week I decided that I'd let a pro with a good supply of parts have a go)

He replaced the limit switch and it seems to be working. As he was poking around checking continuity of the limit switch, the burner lit. After that, it seemed to be working. He recommended replacing the switch saying often his customer won't replace the switch after it starts working and end up calling him back in a few days.

So we are the proud owner of a new limited switch and a working furnace (at least for now).

GlenCoombe · 03-02-2007, 04:22 PM

Very cool....er ... warm. Glad you got that sorted. I wish I had propane onboard. The one thing the old Coachman could do was run you out of the bus with the Suburban furnace.
The electric heat on Airstream One is o.k. but not for boondocking.
It's on the list, just a little ways down in priority.

zamboni · 03-02-2007, 05:58 PM

I sure wish AS er...suburban would come up with a furnace that could use electric (when plugged in) or propane when boondocking. We have a heat strip in the roof air, but our roof air is original and kinda noisy to run all the time in winter...os we use the "propain" furnace. It sure heats up the MH.

lewster · 03-02-2007, 06:15 PM

Quote:

Originally Posted by guy99

RV tech just left. (Since we need to live in the rig until next week I decided that I'd let a pro with a good supply of parts have a go)

He replaced the limit switch and it seems to be working. As he was poking around checking continuity of the limit switch, the burner lit. After that, it seemed to be working. He recommended replacing the switch saying often his customer won't replace the switch after it starts working and end up calling him back in a few days.

So we are the proud owner of a new limited switch and a working furnace (at least for now).

You made the right move in having it serviced by a qualified professional. The electrical path that allows the electrode to fire starts at the battery, thru the sail switch, (normally open, also called an air-prover switch) then thru the limit switch (normally closed) and into the igniter board. The board then will send a spark to the electrode as it opens the gas valve, and the burner ignites. It usually tries this 3 times before shutting down if it does not ignite (newer furnaces with DSI feature).

If any part of this path is blocked due to a failed component..... 'ya just don't get no heat!!!! (as in your open limit switch).