A/C mode issue only on defrost?

2003 JEEP GRAND CHEROKEE LAREDO
134,000 MILES • 4.0L • 6 CYL • 4WD • AUTOMATIC
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STXHAMMER
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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?
Jul 30, 2025 at 8:43 PM
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STRAILER
  • ✓ASE Certified Mechanic
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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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Jul 31, 2025 at 11:19 AM
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STXHAMMER
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I have the manual one I believe. I will check it out and report back. Thank you
Jul 31, 2025 at 5:50 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
Okay them manual one is vacuum operated, check the small tube under the hood like the guide shows. Have a good weekend!
Aug 1, 2025 at 11:38 AM
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