rmaytee

I have searched and read over 30 topics for blower issues, but have not seen this issue reported on the forums.

My AC seems to work fine, blows super cold, but when I go up a hill or accelerate even slightly hard, my air stops blowing in the cab. It gets real loud and almost sounds like something is blocking the airflow. The air is still cold, but I can barely feel it slipping through the cracks of whatever could be blocking the air. The problem has gotten worse over the past couple months--so bad that freeway driving is hardly practical.

This happens no matter what speed I have the air blowing and no matter what mode (AC upper, bi-level, recycled AC, or even vent). The issue is very consistant now and happens every time the motor is working hard, not just sometimes. But as soon as I let off the gas, it blows full strength.

Any ideas?

93XJLI

Did you do the cowl intake mod?

Cherryokee

Your description makes it sound as though one of the vent doors closes and blocks the vents while you are accelerating. If this is true then one of two things may be happening; either there's a vacuum issue that controls a vent door (source, vac ball or control line connection) or it's because of a vent door swinging closed due to the g-forces...

xjheep92

Sounds like a vacuum leak to me. I had a similar problem when I would step on the gas it would go to defrost no matter what mode it was in. the hvac line going to my heater control valve had a rip in it

rmaytee

I'm not familiar with the vacuum system at all. are there any diagrams showing where I should look for the leak?

freegdr

see if its coming out dash vent when this happens

rmaytee

I will check tonight. This much I can tell you. I normally leave the AC on the upper setting, and when the "blockage" kicks in, I can feel the air on my feet, slightly.

DESERTXJ206

I have been in some vehicles where when under hard acceleration it does this. What I believe is that the vehicle slows down the blower speed or sacrifices the air output to gain power. My s10, ranger and my moms ram hemi used to do the same thing. Now it never was more harsh thn before but it was always under real hard acceleration or downshifting to use passing gear for power.

Now on the Jeep I'd probly say its not computer related so its probly a vacuum issue when high rpms.

freegdr

what year we talking about?

rmaytee

99

xjheep92

Yup under the hood there is a vacuum system line diagram. do you have a stock front bumper? look and see if there's a football shaped thing in it. if it's missing there will be a vacuum line that is disconnected. that's the most common place but check all the lines

freegdr

check under hood for vacuum leaks theres a vacuum canister behing pass bumper check both line real good