A/C mode issue only on defrost?

Tiny
STXHAMMER
  • MEMBER
  • 2003 JEEP GRAND CHEROKEE LAREDO
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 134,000 MILES
Hey, my A/C and heat work in the car but only on defrost. It seems the mode no matter what I select only comes out the defrost. Is it the blend door actuator which I think is located behind the glovebox or someone else?
Wednesday, July 30th, 2025 AT 8:43 PM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
So there are two systems, one for the manual system which is vacuum operated, if this is the system you have I would look under the hood for the small vacuum line (plastic) headed from the vacuum reservoir to the engine and then to the firewall, please go over this guide to see what I am talking about.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

If you have the "auto" system the problem will be the mode door actuator, here is the location for that, please let me know which system you have. Check out the images (below). Let us know how it goes.

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Thursday, July 31st, 2025 AT 11:19 AM
Tiny
STXHAMMER
  • MEMBER
  • 47 POSTS
I have the manual one I believe. I will check it out and report back. Thank you
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Thursday, July 31st, 2025 AT 5:50 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Okay them manual one is vacuum operated, check the small tube under the hood like the guide shows. Have a good weekend!
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Friday, August 1st, 2025 AT 11:38 AM

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