A/C Selector?

RICHARD SMITH6

MEMBER
1998 FORD MUSTANG
3.8L
V6
2WD
MANUAL
121,000 MILES

I've put a vacuum smoker on the system and found two small leaks at intake manifold and repaired a rechecked. No more leaks were found in the engine area. Never saw or smelled a leak under the dash. The selector works in every position except vent or A/C. I'm starting to think the switch itself may be bad. Still trying to figure it out.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

What seems to be the problem? Does the A/C not work? Vent control?

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Friday, October 27th, 2023 AT 8:44 AM

RICHARD SMITH6

MEMBER
27 POSTS

A/C not working was already a known issue, the current issue is the selector switch works in all positions (you can hear and feel blend doors moving) except in vent or A/C positions it still only comes out defrost and floor vents. No vacuum leaks were found under the dash using a smoker. Plan on replacing the A/c compressor / dryer etc, in spring (don't need it now).

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Friday, October 27th, 2023 AT 9:46 AM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

It sounds like the air damper door is no working or you have a vacuum leak under the hood that feeds the HVAC system. Please go over this guide and check the images below to se what I am talking about:

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

Here is a guide to how the vacuum lines work and are routed so you can check them out. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)