2nd Gen Non-Engine/Transmission hvac fan not moving air - help!

[DMcLeod]

You can hear the fan at the different speeds, but just a small amount of air coming out the vents. Could a blend door or some other door be broken or stuck? Anyone know how to narrow this down to give me a starting point? Not sure when this started, but recently had the AC serviced and they told me about this... . sure enough. Kinda difficult to heat/cool the cab.

 

[mweiman]

Blower fan

If your fan is running but not moving much air you might want to take it out and make sure there is not a mouse nest or something in the blower wheel. I have had that happen on someone's truck before.

Good luck,

Matt

 

[budnate]

also when the fan motor is out you can look up and see if stuff is all over the evap coil on both sides, mine was surface loaded with stuff, you can gently reach up and brush it off and vacumn it out, I also blew mine off with the air hose.



B. ,

 

[DonTX]

I had the same problem, took the fan on hi to cool. Pulled the fan/motor (only takes a few minutes and is an easy task) the fan was full of leaves! Put on the Geno filter and no more problems.

 

[JMcCoy]

I had the same thing happen. Check your vacuum lines. if there is not enough vacuum, the doors won't opperate properly. Check the line leaving the pump, the fire wall, CAD, transfer case, and under the dashboard. Mine went bad at the vacuum pump. Good luck.

 

[DMcLeod]

I pulled the blower motor - the wheel was very clean. (The original fan went to screaming at me last winter one fine -40F day, so it got replaced with a NAPA fan - the original was clean as well) I reached up and felt a little bit of debris down in the next pocket of the hvac housing, but nothing major. I did a complete test of all vacuum actuators, vacuum lines, and control switch. Everything tested good, all doors seem to be moving, and vacuum holds fine. The one I'm not certain about is the electrical gear actuator attached to the bottom of the HVAC housing. It moves while I move the temp selector switch from hot to cold / cold to hot, but only moves about 90 degrees or so. Does anyone know if that is the correct amount of rotation? You can see the shaft rotating in the 1/2" space or so between the actuator and the bottom of the HVAC housing. Thanks for the ideas... ... . still looking.

 

[DMcLeod]

I still have not figured out the problem. I've been uncomfortably living with it. I recently took the cowl cover off and found everything very clean, no build-up of debris whatsoever. So, I've got unrestricted air inlet. Fan working properly. Recirculating door (vacuum control) working properly. Looking up into the plenum through the heater fan hole, the condenser is clean.



I also recently removed the motor actuator for the hot/cold blend door. I ordered the replacement metal interposer piece from HeaterTreater.com, but I find nothing wrong with my stock plastic piece and the door feels like it is working properly. I can visually see the shaft opening/closing when adjusting the temperature selector switch.



Beyond that, the internal workings of the hvac are inaccessible without dash removal.



I cannot figure out in my mind what could possibly be blocking airflow inside the plenum. The mode doors should allow air one way or another, but never completely block air flow. If they were stuck to one side, I could see having mode issues (i. e. defrost, floor, panel, etc. ) but not a complete blockage.



I am going to start going back through the vacuum lines/control in case I missed something.



I also may cut a hole in the plenum just beyond the fan (like a 2" hole that I could plug later with a hole plug) to see if air will come out.



I am hoping some fresh sets of eyes will see this post and offer some additional suggestions. Thanks for reading.

 

[PBJ2500CTD]

Throwing in a couple of odd thoughts here:

Is the squirrel cage tight on the fan motor shaft?

Did this start when you changed the fan motor? If so, maybe the motor wiring was reversed during manufacture causing the fan to run backward?

 

[DMcLeod]

WHOA, PBJ!!!! I'm suddenly very curious about the crossed wiring.....



I just pulled the motor/fan again today. The fan is definitely tight on the motor shaft. No problem there.



I wasn't very observant - because the problem of no air flow was pointed out to me. I don't know if this problem started when I changed the motor out or not.



1st thing when I get home tonight, I will look into the wiring. The replacement NAPA motor had different color wires (red and blue I think) and no connector, so I spliced it into the stock wiring. We'll see... ...

 

[DMcLeod]

It's FIXED!!

Thanks to PBJ2500CTD! After testing the old motor against the new one, I had the wires crossed. Often it's the simple little things that stump this chump! I can hardly believe I've lived with this condition since I replaced the blower motor nearly a year ago!!! I guess I know alot about my hvac system now. Thanks to all for the help.