1st Gen Blend Door problem

[Super Matty P]

I'm trying to diagnose my AC problem on my 90mtx and I believe it to be the blend door inside the dash. The compressor comes on smoothly, engages and disengages, the system is full and has no noticeable damage. The only problem is that when I turn the AC on it blows HOT air. That's got to be the blend door stuck in the hot position right?

Can anyone link me to some info on how to repair this item? I purchased a Haynes Manual but it has NO SHO information in it....maybe it's not an SHO-specific problem but I'd like to know what I'm getting into before actually doing it.

Any help??

 

[jedhead]

Click here:
http://www.shotimes.com/php-bin/mod...e=article&mode=thread&order=0&thold=0&sid=139
http://www.shotimes.com/php-bin/mod...e=article&mode=thread&order=0&thold=0&sid=142

The only manual to get is the factory manual from helms. You will pay for it, but its worth every penny.

Bob

 

[Super Matty P]

great reads but damn thats going to be annoying to fix. I may just do the simple fix being from alabama with our 74* christmas' I think it'll be fine.

 

[projectSHO89]

I'm assuming an automatic climate control

There's a single fuse that runs the BDA (Blend Door Actuator). Check it first. I've seen reports from owner's who replaced the BDA (a major job) only to find it was just a fuse.

SEARCH keywords "BDA fuse" and my username.

Steve

 

[Super Matty P]

great thanks!

 

[jbspeednut]

Super Matty-
I have the factory manual and have replaced the blend door motor myself.
The first step is to run the self diagnostic test (I presume you have and Automatic Temperature Control (ATC) unit). The control head will detect (some) electrical malfunctions through the self diagnostic test.

To conduct the self diagnostic test...

Ensure the engine is warm.
Initiate the self test by pushing OFF and FLOOR simultaneously and then AUTO within two seconds. The test may run as long as 20 seconds during which the display will remain blank. The following error codes may show on the screen:

01 Replace control head
02 Bend door problem
03 In-car temp sensor
04 Ambient temp sensor open or short
05 Sunload sensor short
888 Testing complete - no test failure (all segments on)

To exit the self-test and restart the system push the COOLER button. Self-test shoud be deactivated before turning off the system and the in-vehicle temperature should be greater than 50F for error codes to be valid.

I had to replace my blend door motor. At the time, the part was about $50 and took me about 10 hours (1 long Saturday). The dealership wanted about $900 to do it. The dash has to come out...there is no way around this step.

Good luck.

Jbspeednut
1990 White MTX

 

[Super Matty P]

I didn't know a few things going into this project so I'll provide a little more info.

My car isn't running right now. I have the intake manifold off right now for some freshening up. I just turned the key to ON and did the self test and it came back with 888. When I get the manifold back on I'll try it with the car running.

I bought the car for a song so I'm trying to gety it going as inexpensively as possible. I thought the ac was defunct when I bought it so if it's a cheap fix I'm all for it. If it's too much then I'll just yank it.

 

[greg geraci]

way around it.

I said forget it and by passed my heater core so it can't blow hot. next winter I'll hook it back up.I don't have the time to pullthe dash. A/c works fine for now.

 

[Super Matty P]

not a bad idea. Heat in alabama is like ice water in the north pole. We've got plenty of it.

Would I feel my AC blowing cold again with the heatercore bypassed and the AC on then? If so thats the path I'll go.

 

[Redline]

I've got a writeup on how to replace the BDA. PM me if your interested.

 

[Super Matty P]

sure, you could email it to me if you prefer. [email protected]

 

[greg geraci]

Absolutely. It will blow cold if the heater core is by passed. Mine is by passed and a/c blows so cold. this winter all I'm going to do is hook up the heater core again and Won't use my a/c. Can't go wrong.I've decided I'm not pulling my dash apart when I can By pass. it's your call.
Greg

 

[SeanMc]

If it's blowing hellfire when it's set to cold, then it's probably the blend door.

 

[Super Matty P]

thanks guys. this has been a great thread.

 

[SonicRiot]

Wow. Have the same problem in my SHO. I assumed it was the blend door becuase the HVAC functions normally, except the Temp out of the vents is always hot. A swift kick ONCE got the blend door to move, but now it's always hot.

It failed completely on the way down to the NY Autoshow. We got stuck in traffic and it was really friggen hot. If it hadn't been for the sunroof open, I might have suffocated from the sweaty stink of three dudes ***** to see the new Challenger and Camaro.


...which friggen rocked, by the way!!!