heat blower motor

roempty · 10-06-2011, 10:08 AM

my 92 2150 blower motor is staying on for some reason I have temp tuun down as far as it will go and propane shut off.Hooked to shore power I went by it this morning and the blower is running.Any glues?

Gene · 10-06-2011, 10:52 AM

I don't know a lot about furnaces in the TT but I know my blower keeps running for a period of time after the furnace shuts off to keep the burner from getting too hot. Sounds like a time delay relay of some sort may be stuck on. Maybe a few "gentle" taps here or there may help.

Hopefully someone with more knowledge can give you a better answer.

Steve Collins · 10-06-2011, 11:53 AM

Inside the furnace is a sail switch. Part of its job is to keep the blower motor going before the furnace fires up to purge any possibility of propane where it does not belong. It also has to keep the blower going for a short time after the heater shuts off to allow everything to cool down. If the sail switch is stuck or defective, the motor will run and run and run.

There are several files about servicing furnaces over in the Files area under
Sunline Coach Owner's Club - Sunline Owner's Files - Sunline Heating and Cooling

I've never had a problem with mine, but those that have report that it is very easy to reach, and if necessary, replace.

mainah · 10-06-2011, 06:18 PM

The sail switch is part of the proofing chain and must close in order for the gas valve to open, the control module is the timer for pre and post purge cycle if there is no ignition the control module simply shuts off the gas now every thing is proofed thermostat, sail switch and over temp switch so as far as it is concerned every thing is fine and it will run until you turn the thermostat off. It's sort of dumb because all it does is blow cold air some of the newer modules will turn the fan off after a post purge but most don't. If it does not light the fan will run until the battery goes dead or some one turns off the thermostat and once the thermostat is turned off the fan runs through a post purge cycle then times out after a minute or so. The original board only tries once to light if it does not fire that's it most aftermarket boards do at least try 3 times before they give up and the better ones now will turn the fan off after a post purge.

**JohnB** · 10-06-2011, 07:32 PM

Quote:

Originally Posted by roempty

my 92 2150 blower motor is staying on for some reason I have temp tuun down as far as it will go and propane shut off.Hooked to shore power I went by it this morning and the blower is running.Any glues?

Hi Ro

Does the furnace actually ignite off when you are calling for heat just it does not shut the fan off afterwards? This helps tell us a lot as if it lights we know the safety and ignition circuit it all working. If it does not light at all, well that points in another direction.

What model number furnace do you have?

Are you handy with electronic and a VOM meter?

What little you have told us may be this "might" be the problem: This fits the newer model Hydrotherms

The fan motor relay is stuck on.
The control board that runs the relay has issues.

On the older models it may be dumber but we need to know if the furnace will light off when it is suppose to.

Page 96 of this Atwood service manual has the sequence of operation for the different models
Sunline Coach Owner's Club - Sunline Owner's Files - Atwood 2007 Service and Training Manual

Give us a model number and we can help better.

Hope this helps

John

**JohnB** · 10-06-2011, 07:56 PM

Quote:

Originally Posted by Steve Collins

Inside the furnace is a sail switch. Part of its job is to keep the blower motor going before the furnace fires up to purge any possibility of propane where it does not belong. It also has to keep the blower going for a short time after the heater shuts off to allow everything to cool down. If the sail switch is stuck or defective, the motor will run and run and run.

There are several files about servicing furnaces over in the Files area under
Sunline Coach Owner's Club - Sunline Owner's Files - Sunline Heating and Cooling

I've never had a problem with mine, but those that have report that it is very easy to reach, and if necessary, replace.

Hi Steve

Do not know what brand or model you are referring too, however the sail switch is in the safety circuit of the gas valve along with the over temp limit switch. It's purpose is to insure that the blower is running fast enough to remove heat from the combustion chamber and have the correct air/gas mix. It does not turn the fan on or off it only works the gas valve. Did I miss read your post? It sounds like you where saying the sail switch turns the fan on and off.

And the sail switch on the newer 8500 series hydroflames is buried so deep inside the fan housing you have to take the entire unit apart to find it.

Here is what Atwood says

Quote:

Atwood Wrote:

The sail switch is an air proving device. It is a safety component that will not let ignition occur until it sees 75% of the motor’s rpm’s. It insures that the combustion wheel is rotating fast enough so that there is a proper air and gas mixture for smooth ignition.

There are different size sail switches. The noticeable difference is the size of the paddle on the switch. Each switch is matched to the size of motor it must respond to.

NOTE: All 85-IV use the same sail switch. When the paddle of the switch is
depressed, there should be continuity through the switch. If a sail switch needs to be replaced, it should be replaced with the exact same size. If a larger switch than the original is used, it will probably not close when the motor reaches 75% of its rpm’s and therefore keep ignition from occurring.

The most common problems with these switches are bent paddles, loose wire connections or an obstruction between the paddle and switch contact

Hope this helps

John

roempty · 10-07-2011, 05:25 AM

what I'm saying is I used the heat last time I camped and worked fine.I came home from camping and have trailer in my driveway plugged in with gas off themostat off and the temp here got very cold and the fan comes on and is running won't shut off.I going camping today and will turn on The gas and see if she works ok.Maybe it is just thermostat just is not shutting off all the way

**JohnB** · 10-07-2011, 09:28 AM

Try unhooking the thermostat. Only need to unhook one wire. If you have the combo AC and furnace T stat you will have to find the right 1 wire.... as there is many in there for the AC as well. If you have the older furnace only T stat there is only 2 wires in it.

Good luck and come back with a model number too if you still have problems.

John

mainah · 10-07-2011, 07:35 PM

If the gas is off it will still run if the temp drops enough for the thermostat to call for heat and the fan will not shut off, if the "off " part of it does not work. Like John B said pull one wire off the thermostat it's is possible the "off " switch does not work it's pretty crude. The power to make the heater go comes through the thermostat then to the control module after passing through the proofing chain. Pretty much any non mercury thermostat will work on your system if you find it to be bad.

roempty · 10-08-2011, 04:36 AM

Thanks for all the help switch in thrmostat was still on.Thought I was going to break it to shut off