Very little HVAC airflow - SOMETIMES

[slovcan]

The position indicator marks in your photos look good. Defrost will engage the compressor so that’s normal as others said. If there was rust on the blower motor shaft when you pulled it, look for a water leak at the cowl vent screw hole directly above it. Put a mirror in with the blower removed and you’ll see the screw sticking though. Put a hose to the windshield and see if water comes though. Goop the hole and screw with RTV and that should fix it. Wet carpet is another indicator.

Good morning. Yes, I have been though the stupid screw process a few years ago. What a stupid place to put a screw. I did goop it over then, but saw this time around that the goop was gone. I have rubber winter mats in and saw a bit of water in the mat, so checked, and re-gooped.

I bet there are thousands of owners who don't know about the stupid screw. Good that you mentioned it. Thank you.

Also, thanks for confirming the index positions are OK and the Defrost-A/C function.

Cheers,
Glenn

 

[Sprinter77]

Hi guys I'm having the same low air flow problem. have changed the blower multiple times as well as resister. what does the screw that is mentioned do about airflow?

 

[dryslk]

FYI there is a RESET HVAC Controller Program on You Tube Try this sometimes when working on my Truck if the Batt goes 2 low the HVAC/ Heat Controller gets Confused doing the Reset Cures the Prob hope this helps Best of the New Year Everyone from the Great Frozen Canuckistan Temp Now is - 31 w/wind -45

 

[Ehall8702]

Man pulling the dash isn't fun at all! My subwoofers dislodged the flappers in the airbox , so I had to pull the dash and HVAC box and modify a bit, actually wrapped the "hinge pin" with mechanic wire (melted thru plastic and mad a sort of retaining ring) so it wouldn't happen again.

 

[Sprinter77]

FYI there is a RESET HVAC Controller Program on You Tube Try this sometimes when working on my Truck if the Batt goes 2 low the HVAC/ Heat Controller gets Confused doing the Reset Cures the Prob hope this helps Best of the New Year Everyone from the Great Frozen Canuckistan Temp Now is - 31 w/wind -45

thanks for that info. will try looking at that video. it's a freezing 52* here for us old folks in Arizona. Happy New Year

 

[Sprinter77]

Man pulling the dash isn't fun at all! My subwoofers dislodged the flappers in the airbox , so I had to pull the dash and HVAC box and modify a bit, actually wrapped the "hinge pin" with mechanic wire (melted thru plastic and mad a sort of retaining ring) so it wouldn't happen again.

Thanks for your reply. Yeah I'm afraid that is where this is going, pulling dash... here is AZ we need all the air flow we can get in the summer months. Have a Happy New Year

 

[Sprinter77]

FYI there is a RESET HVAC Controller Program on You Tube Try this sometimes when working on my Truck if the Batt goes 2 low the HVAC/ Heat Controller gets Confused doing the Reset Cures the Prob hope this helps Best of the New Year Everyone from the Great Frozen Canuckistan Temp Now is - 31 w/wind -45

Thanks again Dry Slick... like the looks of your car...

 

[slovcan]

Hi guys I'm having the same low air flow problem. have changed the blower multiple times as well as resister. what does the screw that is mentioned do about airflow?

Hi Sprinter,

The screw is under the hood. Open the hood and it is about the second closest to the right side fender. The screw hole goes into the top of the airbox where the blower motor lives. Water starts to leak around that screw. Doesn't affect airflow unless water kills the motor, of course.

Maybe you have an actuator issue. That doesn't require pulling the dash. Another possibility I learned about here is the possible collection of leaves or other debris in front of the evaporator - in through the blower opening and up over to the left.

 

[Ehall8702]

Thanks for your reply. Yeah I'm afraid that is where this is going, pulling dash... here is AZ we need all the air flow we can get in the summer months. Have a Happy New Year

I feel for ya! It's a crappy but necassary job. Good luck!

 

[Aeroscream]

Been having similar problems with my 2000 C3500. Before moving to NW AZ, back in Central IL only when in heat mode did it want to fail. Barely any air flow at all, virtually nothing coming out strong in any vent in any mode. You could ramp up and down the blower motor low to high and hear air flow moving all around, but no output. Then at highway speed cold air rushes in freezing you and more so the passenger out. It never acted up in A/C modes.

I now have the dash apart after a weekend trip to a state park north of Vegas where my wife and I struggled to keep heat in the truck. I have replaced the actuator nearest the gas pedal, that runs the vent/defrost/floor mode door(s). I bit the bullet and bought a new climate control panel, ($ ouch $), and am waiting for a temp mode actuator to arrive to change it out behind the ash tray.

The fresh air/recirculation actuator and door seems to be working flawlessly, and I cleaned out the chamber after removing the blower motor with a wet/dry vac and a rigged up 5/8 clear tubing to my vac's hose.

I hated throwing parts at it instead of troubleshooting, but I only want to take the dash apart once and it was an intermittent problem.

We'll see. Luckly, we don't often use the heat mode much now, but it sucks as you all know when it fails.