Blower won't stop

[Fam-Bambi]

We have a 2012 22fb sport. I went to plug in at our storage facility today and the blower came on. The thermostat had been left on from our last camping trip, so I turned it off, but the blower did not go off. It kept running. I unplugged and it was running off the battery. I turned the battery off and it stopped. When I turned the battery back on, it came on again and won't stop. Any ideas? Thanks.

[Al - K4GLU]

Assume you're talking about the furnace blower since you don't specify. You can always pull the furnace fuse to stop the blower running until you can get it fixed.

[Lumatic]

If your battery is drained when shore power is plugged in 12v can do funny things. See your battery has a full charge and see what happens. If that doesn't fix the problem the next thing I would do is disconnect the thermostat. If that fixes the problem you probably need a new thermostat. You don't need anything fancy get the cheapest one you can from Wallyworld that has an actuator. It will say for 24v, but it does not matter.

[TG Twinkie]

Sounds like the temperature sensor in the plenum has failed. The furnace thinks the blower is still hot. It will run until the plenum cools below the limit of the temp sensor. I am assuming the burner is not lit.

[TG Twinkie]

Meant to say the plenum is still hot.

[Fam-Bambi]

Battery is charged. After thermostat is turned to "off" the blower runs and runs. We can turn it off only by hitting the reset button inside the grill of the blower.

[Fam-Bambi]

The burner has only been on for a few minutes to test that the heating part of the sequence is working. So it never really got very hot.

[Lumatic]

Originally Posted by Fam-Bambi

Battery is charged. After thermostat is turned to "off" the blower runs and runs. We can turn it off only by hitting the reset button inside the grill of the blower.

Don't just turn the thermostat off, disconnect the wires at the thermostat and see what happens. If disconnecting the thermostat stops the blower and then crossing the wires starts to cycle the furnace the problem is the thermostat.

[Fam-Bambi]

Will try that. We already had to replace the thermostat once already last fall, just a couple months after buying the Airstream.

[TG Twinkie]

It's not that the plenum is hot. It's that the temperature sensor in the plenum thinks it is. The only time the room thermostat will stop and start the fan in direct response to the thermostat is when the plenum is cooled and the temp switch is satisfied that the plenum is cool enough for the fan to shut down.

[rumrunner]

My wife says I'm never afraid to ask a stupid question, so maybe does your thermostat have a second switch which turns the blower on directly like mine does?
tim

[TG Twinkie]

No such thing as stupid questions. And a second fan switch is certainly a possibility.

[Sodbust]

The heater fan motor kicks on our 72 Overlander starts up when the Thermos tells it to fire up.. Ok,, but even with the gas turned off it will still try to run,,

What I have had to do is to disconnect the thermostat when we have it all set for storage or it will drain the battery..

The thermostat is not stock, but some new item with 2 AA batteries inside,. There is no off and on switch so just have to pull the face off and park it on the shelf above the bed till we need heat for real.

Don't know if this is the same problem or not but our stick and staple SOB had an off and on switch at the bottom we could shut if off while in storage.

Sodbust

[richinny]

i'd do a reset to the thermostat settings. check the back pages of the thermostat manual.

[Fam-Bambi]

No 2nd switch on the thermostat. I disconnected the thermostat and the blower is still running. Looks like we will have to take it in for repairs. Thanks everyone.

[lewster]

Originally Posted by TG Twinkie

It's not that the plenum is hot. It's that the temperature sensor in the plenum thinks it is. The only time the room thermostat will stop and start the fan in direct response to the thermostat is when the plenum is cooled and the temp switch is satisfied that the plenum is cool enough for the fan to shut down.

Just for informational purposes, there is no temperature sensor in the plenum. There is an ECO, or emergency cut-off sensor, which will shut the furnace in an over-temp, over heating situation. The only sensor responsible for shutting down the furnace during normal operation is the wall thermostat.

In older furnaces, there is a TDR (time-delay relay) that is responsible for the purge cycle after the burner has extinguished after the t/stat has been satisfied. In newer models (such as the one under discussion), the igniter board has this job. It is also responsible for the blower coming on, checking the circuit thru the sail switch and ECO, igniting the burner and then extinguishing it and then controlling the purge cycle.

This board also tries 3 times for ignition and will shut down the blower if this doesn't occur. His igniter board probably needs to be replaced.

[Fam-Bambi]

Just got repair. It was the circuit board for the blower. Thank you for all of the support in helping us narrow down the problem. Happy camping!