Restriction in outside air coming into heater/AC

[Blakers]

Something is restricting the outside air flow coming into the heater/AC on my 2003 Ram. Unless I have the controls on recirc, there is almost no air flow. The doors are working properly. The blockage is before the recirc door. Is there anything like a screen or filter inside the plastic cowling where the air comes in that could block air flow?

Thanks,
Blake

 

[lpennock]

Should be a screen on it if I remember correctly. Been ages since I had the cowl off.

 

[Prairie Dog]

Remove the cowl and you'll find the HVAC inlet on the passenger side tucked under the firewall overhang. I don't believe there's a screen on it and it's possible for leaves, mice or ? to come in where the cowl drains through the qtr panel.

 

[wcjp]

Check fan box for leaves/mice/blockage. Also, is your recirc door broken?

 

[Blakers]

Thanks guys. No, the recirc door is fine and the fan box is fine. Any restriction is before the door. If there are leaves blocking air flow in the cowling, would be be visible with a flashlight from the top?

 

[Prairie Dog]

Thanks guys. No, the recirc door is fine and the fan box is fine. Any restriction is before the door. If there are leaves blocking air flow in the cowling, would be be visible with a flashlight from the top?

No, the inlet sits high under the cowling so it's protected from washing or rain. It's hard to imagine you could get enough debris in there to block it because the bottom of that area is well below the inlet. Still it's not a bad idea to check it and if it doesn't have a screen then I would fabricate one.

 

[Bob4x4]

It should have a screen. I did an 06 today that had a bit of debris stuck in the screen itself and a fairly high amount of dirt/sand that had found its way into the housing

 

[Blakers]

I FOUND IT! Today I lifted the passenger side of the cowl up which revealed where the HVAC intake air comes in. On the far passenger side there is a triangular opening on top with a foil cover sealed down over the area where the screen is located. After carefully lifting the foil off the screen can be seen with the help of a mirror. It was completely impacted with black oily dust, dirt and weed seed particles. I doubt any air was getting through it at all. With a toothbrush I was able to get most of the dirt off of it, then I rigged up a blow gun with a short plastic tube with an arc shape that was able to get almost all the debris off the screen.

HORRAY! Another problem solved! Now I can remove the little 3/4" square piece of wood I zip tied to in the recirc doorway so some cab air could get into the heater of my truck last winter. Hopefully now I can enjoy plenty of airflow with my heater and AC. And the windshield should not fog constantly all winter unless the defrost is on full time.

I would say the screen in the heater intake is a very poor manufacture's design. That screen should be in a serviceable place under the hood, perhaps even incorporating a replaceable filter element that could easily be changed.

Thanks for your help guys,
Blake

 

[Prairie Dog]

Cool, thanks for the update.