AC Not Engaging, stuck on Defrost

[dbdynsty25]

Hey Guys,

Been on this forum forever but haven't posted much over the past year or so. Gotta quick question.

A couple months ago I was using my winshield defroster and when I went to switch it back to the AC...it took me a couple tries to get it engaged. Fast forward a couple months worry free...it did it again and now it won't switch at all. The thing is stuck on defrost and I can't get it off. I can turn the knob all I want, and it never engages.

Someone once told me that it would be a vacuum hose...but most likely the car would be running rough if that was the case. It's not...it's running like it always has.

Has anyone ever had that happen to them? What was your solution? What are some things to look for or try?

Thanks in advance.

Damn I missed this place.

BTW, I've got a 95 GT, stock besides the springs and suspension.

 

[dTas95GT]

its a hose/connection under the dash. i had the same problem. actually i never turned it as far as AC but the heat wouldn't switch away from Defrost. i didn't bother looking at it myself. i had to take the car in for a tune anyway so i had them look at it. its a quick fix if you can find the right thing to hook back up. no new parts needed.

g'luck.

 

[Rel]

Chances are it's the vacuum line that runs across near the top of the firewall in the engine bay. It's a very thin black vacuum line that starts on the drivers side and ends up on the passenger side going in behind the glove box.

I stopped getting air through my A/C vents too, but mine was a different problem.
It was this guy behind the dash.
http://forums.stangnet.com/showthread.php?t=411084

And not to try to discourage you, but if the vacuum like cracked and is now separated, it wouldn't explain why it started acting up, then worked, and then died.
I had the exact same issue where it did work, and sometimes it took a few time's. Then it eventually just died and stopped working all together.
When I did my heater-core swap I replaced it and whataya know.. it works.

 

[dbdynsty25]

its a hose/connection under the dash.

Awesome, thanks for the reply. Do you have any idea where it's located so I can just reconnect it? I was hoping that's all it was...if that's it, I'm gonna be lovin' it.

 

[dbdynsty25]

Thanks Rel...I had a feeling there might be something behind the dash controlling that. Maybe that's my problem too. I guess it's worth the 15 or so bucks to try eh?

 

[Rel]

Worth the $15? Yes.... but is it worth taking out your dashboard to remove it? That's up to you.
Definitely troubleshoot the vacuum line first and go from there.

 

[dbdynsty25]

Details, details...

 

[Rel]

Details on removing the dash? or the vacuum line?

 

[Rel]

Okay well I went searching through some of my pictures and here are the best I could come up with.
You need to check the small vacuum line that is zip tied to the big line. Follow it from the booster all the way to where it enters your glovebox through the firewall.

 

[dbdynsty25]

Oh shoot...I'm sorry Rel...I was saying "Details, details" in response to the part about taking the entire dash apart. Meaning...sure, I'll spend the 15 bucks on the part, but do I want to invest so much time taking the thing apart.

Sorry about that...hard to tell inflection on a message board. I appreciate the pics anyway...I'll take a look at those lines this evening.

 

[Rel]

Details on taking out the dash... that's a full days work. I did mine + replaced heater core in about 8-10 hours on a saturday.
Basically everything has to go. I used my Haynes manual for instructions of ripping it out. It has a step-by-step on dash removal. If you don't have one I strongly suggest you pick one up at your local auto parts store.
It goes from this....

..... to this

Check out this link for the screws/bolts that need to be removed.
I made these up when I first did it a few months ago but I'm not sure if that's ALL of them.. I think it is.
http://webpages.charter.net/forestrat/howto/dash_removal/