HVAC Controls

[gpse_97]

MY HVAC controls wont switch modes. (upper, lower, defrost, etc).

Any ideas on how to fix it?

Is there a vaccume line that I need to run anywhere???

[stockgp]

resistors may have gone bad? could also be a vacuum line, though

[gpse_97]

where is the vaccume line located?

I am pretty sure thats what it is, where do I connect the vaccume line from the engine to on the HVAC unit?

[stockgp]

resistors control the speed settings. i'm a little backwards. i believe the line that runs to the interior runs off the t-shaped connector by the washer fluid reservoir

[blackbombshell95]

if u need the hvac unit for a garnd prix let me know. mine from my 95 is forsale with 2 knobs

[DiscoStudd]

Do a search, this exact topic just came up about a week ago...

[GP1138]

if u need the hvac unit for a garnd prix let me know. mine from my 95 is forsale with 2 knobs

 

His is different than yours.

 

Do a search, this exact topic just came up about a week ago...

[Kalgorn]

I just fixed this problem. It was my vacuum lines. Turns out I was completely missing the check valve on the vacuum lines and one of the lines that goes to the check valve controls the HVAC.

 

I used these two vacuum diagrams:

 

 

 

The only problem with the first diagram is the check valve is shown as backwards (unless I got a fluked check valve?).

 

Unfortunately, a little bit more info is going to be needed to diagnose this problem. My problem was complicated because lines weren't hooked up and I was needing pieces. You could just have a leak somewhere.

 

As long as your engine bay is set up the same as mine (both are DOHCs), find your cruise control module. There are two vacuum lines coming off of it; one large hose and one small hard line. The hard line comes down to a T. Left side of the T goes to the vacuum ball (line runs under the battery/washer fluid tank) and the other side connects to the check valve. The check valve should look like this:

 

 

The MAP sensor line is a vacuum line that runs behind your engine (around the rear plugs) and curves around towards your cruise control module. There should be a small rubber connector on it to attach it to the check valve (my dad threw mine away ). The HVAC line runs under a bunch of stuff to the left of your driver's side strut tower and it has a rubber elbow on it.

 

Hope this helps you. If you run into any problems or have any other questions, feel free to IM me at CreepingSkulls while it's still fresh on my mind.

 

If I find some free time either this week or next, I think I'll write a FAQ on this with pictures to help people out.

[gpse_97]

Thanks for the replies, well I doubled checked and all the vaccume lines under the hood are looking good.

I think the vaccume line breaks or doesn't connect properly on the interior. Where does that vaccume line run into the interior? I think I might run an entire new line.

[Turbo231]

On my 93, which is the same as yours, my HVAC module did go bad. Since I find electrons easier to chase then vacuum lines, pulled cable harness going to the vacuum module and tested for signal...and found none. I ohmed the cable and found it OK, so it's my little module. Can be had for ebay from 5 to 25 bucks, with or without rear defrost. Good luck.

 

P.S. You can get all the voltage/ohm/signal information from your service manual. You can get one on ebay too.

[Supreme Cutlass]

Thanks for the replies, well I doubled checked and all the vaccume lines under the hood are looking good.

I think the vaccume line breaks or doesn't connect properly on the interior. Where does that vaccume line run into the interior? I think I might run an entire new line.

 

There's a black plastic line that runs from engine bay to the firewall. after the firewall it switches to a softer, colored (probably purple) line. That purple line runs to a switch that adjusts the vacuum to the different places ( which should be checked first, since it's the easiest. ) that's right above the convenience center. From there vacuum goes to the individual acutators.

[gpse_97]

Thanks for the replies, well I doubled checked and all the vaccume lines under the hood are looking good.

I think the vaccume line breaks or doesn't connect properly on the interior. Where does that vaccume line run into the interior? I think I might run an entire new line.

 

There's a black plastic line that runs from engine bay to the firewall. after the firewall it switches to a softer, colored (probably purple) line. That purple line runs to a switch that adjusts the vacuum to the different places ( which should be checked first, since it's the easiest. ) that's right above the convenience center. From there vacuum goes to the individual acutators.

 

so I Should check the purple connector for vaccum. What convenience center are you talking about exactly? are you talking about the DIC?

[Supreme Cutlass]

Honestly, I dunno what the acronym "DIC" is for, but i'm talking about the unit that has the chime module, etc. it's on the passenger side right next to the blower motor, closest to the floor. RIGHT above it is the switch

[Supreme Cutlass]

I forgot to ask, where do you HAVE air?

If you still aren't sure what i'm talking about, go to my car domain site and the convenience center that i'm talking about is resting on the floor, passenger side. I took it off so I could get to that switch.

[gpse_97]

hey, the DIC is the "Driver Info center" or Trip computer thingy. (that shows ur MPG, fuel remaining, etc). Anyways air is coming thruw the floor and windshield from what I can tell.

 

 

so how hard is it to get to this switch???

[Supreme Cutlass]

lol not hard at all, on my olds you just remove one panel and it's there.

 

I had to do ALOT of little repars when I first got the car...

[gpse_97]

Thanks for the help, I fixed it!!!

The purple vaccum line was cut in half! So I reconected it down there and all is good now.

thanks once again!

[Supreme Cutlass]

woot!