2007 F-53 Dash Blower quit working

[Black-Bear]

We purchased a (used) 2008 Class A on a 2007 F53 chassis this year.

Within a few weeks the dash blower wouldn't come on after I started the engine. Curiously, it started working again when I shut down the engine and restarted it.

This summer it worked for the most part (A/C, VENT, etc.), but occasionally it would act up and not start up after starting the engine the first time. No problems after restarting the engine again, though.

Didn't seem to matter whether it was a cold start of after stopping at a gas station, rest area, etc.

A few weeks ago it wouldn't come on no matter how many times I restarted the engine. However, sometimes it would come on after driving for some time.

You guessed it - now it's not coming on at all.

So far I've checked the following:

1. Blower resistor: in pristine shape and tests fine with a multimeter
2. Power to the blower leads: no power on any settings
3. Power to resistor: no power on any settings
4. Speed selector switch: continuity fine on all settings, no power to the switch
5. Mode selector switch: hard to tell, but I do hear a swooshing sound when I change the mode (baffles moving?)
6. Passenger compartment fuse (#7): continuity OK
7. Power Distribution Box fuse (#23): continuity OK
8. Power Distribution Box relay (#5): not tested, but swapped out with started relay. Blower still dead, engine starts fine with the former blower relay.

Visible cabling looks fine. Before I start removing insulation to visually inspect the hidden wires, anything less invasive that I can check?

Would it buy me anything if I checked the fuse boxes and the relay connector for power?

Is there a sensor somewhere that may have cut power to the system? Another fuse?

[House Husband]

On the circuit board in your BCC is an ignition relay that may supply power to your HVAC system. RV Custom Products may be able to supply a wiring print.
https://rvcustomproducts.com/

Richard

[Skip426]

Well first things first : Ford didn't supply the dash section of your HVAC , your coach manufacturer did and they sourced it from a supplier of dash HVAC equipment. Engine mounted compressor, and condenser in the cooling stack came with the chassis from Ford , maybe the receiver dryer.
So lets start with info on your coach builder and the manufacturer of the HVAC system . Any info there ? Evans/Tempcon ? Denso ?

[HarryStone]

However, Ford DID supply the power to the blower.

[Black-Bear]

Originally Posted by Skip426

Well first things first : Ford didn't supply the dash section of your HVAC , your coach manufacturer did and they sourced it from a supplier of dash HVAC equipment. Engine mounted compressor, and condenser in the cooling stack came with the chassis from Ford , maybe the receiver dryer.
So lets start with info on your coach builder and the manufacturer of the HVAC system . Any info there ? Evans/Tempcon ? Denso ?

It's a 2008 Four Winds (Thor) Hurricane 34B.

I'll give Thor a call tomorrow to see if they can send me the wiring diagram.

[Black-Bear]

Originally Posted by HarryStone

However, Ford DID supply the power to the blower.

Hmmm... makes me wonder about the ground. Haven't checked that yet.

[HarryStone]

Originally Posted by Black-Bear

Hmmm... makes me wonder about the ground. Haven't checked that yet.

Check fuses and check blower relay first.

[Black-Bear]

Originally Posted by HarryStone

Check fuses and check blower relay first.

Did that - all look fine and multimeter continuity check confirmed it.

I swapped out the relay with another one and it didn't fix the issue.

BCC is next on my list.

[Sweetbriar]

Go here - https://www.proairllc.com/design-eng...empcon-guides/ for troubleshooting guides and power distribution diagrams.

Thor did not use the BCC to route power for the dash fan.

[Black-Bear]

Originally Posted by Sweetbriar

Go here - https://www.proairllc.com/design-eng...empcon-guides/ for troubleshooting guides and power distribution diagrams.

Thor did not use the BCC to route power for the dash fan.

Thanks - that's good information!

I just got off the phone with Thor and was advised to take it to a dealership since Thor doesn't have good diagrams for 2008 models.

[HarryStone]

Did you have power to the relay? Continuity checks only go so far in troubleshooting.

[Black-Bear]

Originally Posted by Sweetbriar

Go here - https://www.proairllc.com/design-eng...empcon-guides/ for troubleshooting guides and power distribution diagrams.

Those docs are great - thanks!

[Black-Bear]

Originally Posted by HarryStone

Did you have power to the relay? Continuity checks only go so far in troubleshooting.

Good point. I'll make that the next item to check.

[avfordguy]

Sometimes it is best to start at the source ( blower motor) and work your way back, also it is best to load check the feed circuit and load test the grounds, normal dvom will trick you believing it is ok.