HVAC vent problem

[CobraM23]

Hey guys this just happened yesterday. My cars HVAC stays on defrost no matter what I set it to. It will switch off when in the OFF position but no matter what A/C, MAX A/C, FLOOR it blows out the defrost vents. What could possibly be wrong and how do I fix it?

 

[mrvax]

Sounds like whatever cable is used to deflect the air to the floor/vent/dash is not working. Check fuses.

 

[FriscoGT]

There is no "cable" which controls this. It is a vacum line, so check for a small vaccum line that is broken or disconnected under the hood. If broken, a new hose from an auto store will only be a few bucks.

The reason it is stuck on defrost is by design, so that if this hose breaks you can still clear your windshield.

 

[mity2]

Sounds like whatever cable is used to deflect the air to the floor/vent/dash is not working. Check fuses.

Dude..... we have Vacume actuated Vent deflector. No cable here. Check behind A/C panel for leak from hoses

 

[CobraM23]

Thanks for the replies. Where exactly under the hood should I be looking for? I have been leaking water right above my passenger header collector from this rubber grommet that seems to be right in front of where the heater is located at under the passenger dash. I figured it was weird since I dont use my A/C at all.

 

[FriscoGT]

I've only replaced one on a 95 v6, and it was located at the top of the engine bay, running alongside the firewall. It should not be buried at the front or down low on the sides.

If I recall correctly it was a 3/8" tube at the ends connected by hard plastic in between. The plastic is what broke, but I replaced the entire lenth with new tubing and it worked fine.

 

[mity2]

and also look behind HVAC panel. there is bunch hoses there

 

[sgarlic]

Wow, to whoever read my original post, I thought I was posting on the 5.0 side for that question. Sorry for the completely wrong answer.

My original post referred to the foxbody's, where if you disconnect the a/c vacuum line at the vacuum tree it will only allow you to use Defrost, or Off.

 

[CobraM23]

Ok Ive taken out the HVAC control panel. On the back there is a yellow, white, red, blue, and black line. Yellow goes to what looks like a solenoid of some sort. The red and blue go up to the defrost or looks like it. Ive found the black line where it goes through the firewall. Ive pulled it apart where the plastic piece is in the middle and put my thumb over the hole to simulate vacuum but still no fix. Does that mean the vacuum leak is closer to the control unit than the line in the engine compartment? Any ideas guys?

 

[Mickey21]

Does anyone else know the answer. My 97 started doing this about a week or so ago. Exact same issue. Aint that wierd how that happens. It will only blow to the defrost as well. I will check my lines as well, just hadnt gotten around to it. Thought I would ask up here in case someone has already done it. I searched my repair manual up and down and only saw a BRIEF mention to the vacuum controls but not much else in there on it. If I figure it out, I will post back here...