EATC Going crazy!?

[shosound]

I got in my '93 MTX yesterday and as soon as I turned they key to run the Blower went full on on defrost for a second, shut off, then repeated this over and over again. I'm thinkin it might be a relay, but I don't know where they are. Anyone got any ideas? The display said OFF the whole time the thing was acting crazy too. I pulled to fuse for now so I don't have to listen to it. It didn't matter if I had it on or off, it was nuts as long as it had power.

 

[F-22 Raptor SHO]

do the eatc automatic diagnosis....as outlined here:

http://www.v8sho.com/SHO/EATCandMaxAC.htm

though outlined for the v8 SHO, the test is the same.

 

[ohfosho]

almost a garentee the BMC. if your EATC was off at the time, it is for sure the problem. i had the same issue when i bought my car. full on all the time, i pulled the fuse untill i got a replacement (someone on this board prolly has a good used one for you to buy, or i have heard that some people were able to get a hold of new ones at the dealer?)

where it is: passenger side, under dash, pull down vanity cover (black plastic), 2 screws (bolt heads) hold it in. also partially accessable through glove box (when let open right up, past the holding point)

what it is:

but remember if you have it on auto, it will be trying to get the interior to that temp. that is shown on the screen, so it will start off blowing high. you can override the auto by setting the blower speed yourself. i usually leave mine on vent, and when its nice out, at 19-21 (celcius)

 

[sdpatt]

Check the battery voltage with the engine running (13.5V+) and stopped (12.0V+). If the voltage is too low, the EATC is just one thing that will not work as designed. This is not the most likely cause, but an easy check.

 

[shosound]

Blower control sounds spossible. If you read my first post I said it runs full spped and stops, then full speed then stop, etc. The display says OFF, I can switch it, but the air still comes out the defrost area. Do you still sthink the blower control, voltage is fine. the car was truned off, when I restarted it did this

 

[projectSHO89]

Blower control sounds spossible. If you read my first post I said it runs full spped and stops, then full speed then stop, etc. The display says OFF, I can switch it, but the air still comes out the defrost area. Do you still sthink the blower control, voltage is fine. the car was truned off, when I restarted it did this

Yeah, blower speed control module

Steve

 

[shosound]

just out of curiosity, where are the relays in our cars? so I can check it too

 

[projectSHO89]

just out of curiosity, where are the relays in our cars? so I can check it too

Relays? I though you were trying to fix your HVAC system....replace the BCM.

We don't need no stinkin' relays!

Steve

 

[dstig1]

Weird EATC behavior can easily be caused by a dying battery. How old is it? Sometimes that doesn't matter - I had a new one die on me after a year or so and got it replaced under warranty. Thing I noticed was every time I stepped on the brake, the electricals would go nutty. I assume it was the load from the brake lights dropping the system voltage too much.

 

[projectSHO89]

Weird EATC behavior can easily be caused by a dying battery. How old is it? Sometimes that doesn't matter - I had a new one die on me after a year or so and got it replaced under warranty. Thing I noticed was every time I stepped on the brake, the electricals would go nutty. I assume it was the load from the brake lights dropping the system voltage too much.

He doesn't have a wacky EATC, he has no control over the blower motor.

Steve

 

[shosound]

Thanks for the info projectsho