Hear blower, but A/C air not blowing through vents?

HIVELY2013

MEMBER
2001 DODGE RAM
5.9L
V8
4WD
AUTOMATIC
170,000 MILES

Hello!
I can hear the blower (and can hear it change speed/power when moving through positions), but my AC will stop blowing out cold air randomly. When it stops, there is no air moving through the vents. Usually, within a few seconds, it begins flowing again. Unfortunately, it's becoming more and more frequent, for longer amounts of time (and hotter and hotter).
Fuses are intact.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,621 POSTS

Hi,

Does this seem to happen when the engine us under a load such as going up a hill? I ask because the HVAC duct work and control doors are operated using engine vacuum. Based on what is happening, it sounds like either there is a vacuum leak under the dash, the mode door vacuum actuator is faulty, or the vacuum supply from the engine is leaking.

Try this. Turn the system on with the engine running. See if you can hear a hissing sound from anywhere under the dash, including where the controller is. Additionally, check for engine vacuum leaks under the hood on the engine.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Try that and let me know the results. Also, Chrysler and others love using vacuum tubes. They are known to dry out and crack. See the pic below. It shows what I'm referring to.

Let me know.

Joe

See pic below.

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Monday, June 17th, 2024 AT 8:16 PM

HIVELY2013

MEMBER
2 POSTS

I wanted to confirm I received your response. Also, this action happens at cruising speed. At first, I was thinking it was when I was accelerating hard, but that is definitely not the case. It can actually happen while idling, although it doesn’t seem to stop pushing air completely then, just goes into rotations of barely pushing it out.
I’m also going to pull up my most recent work on my A/C (a couple years back)- because there was a ton done on it. I wouldn’t expect any hoses to be dry/cracked by now.
I will run through the items you suggested, but to be completely honest, probably later this evening, we are under a heat advisory, and it is nasty out there today!

Thank you!

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Wednesday, June 19th, 2024 AT 6:39 AM

JACOBANDNICKOLAS

MECHANIC
109,621 POSTS

Hi,

Usually, the hoses under the dash aren't checked. However, anything is possible. Let me know what you find with the receipts. Also, when this happens, does the air flow redirect or does it just stop?

Joe

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Wednesday, June 19th, 2024 AT 6:59 PM