corvette95

Blend door is hot all the time, I have tried to make sure it wasnt stuck (it's not) I can turn manually move it with car off, but it will manuall go back to full hot. Guess I need a blend door motor, any tips on how to replace.

AGENT 86

Remove the ECM, then remove motor.

No Guru on HVAC, but if the motor is moving the door back, sounds like it's working, but not receving the correct command.

I would be looking more towards the control head and the programmer.
Cleaning up the control head cured some whacky problems I had. It's been 7 years and no problem since.

Engle has a nice write up here

http://forums.corvetteforum.com/1568603057-post3.html

Some info on the programmer is here

http://www.batee.com/corvette/acrepa...oard/index.htm

HVAC from my 86 FSM

http://members.shaw.ca/dankai/HVAV'S.pdf

http://members.shaw.ca/dankai/HVAC%20Electrical.pdf

corvette95

I have cleaned the control head, I figured the motor stripped out , I disconnected battery, it should move the blend door to neutral 75 when it re powers up. It stays all hot. I have a couple of extra control heads (and programmers) I guess I could try but I am thinking blend motor

corvette95

Just replaced head unit, no change. I thought the blend door was electric. is it vacuum too? Any tips on replacing it?

AGENT 86

It's right above the flat duct, pull the ECM and remove it.

Here's a clear shot of it.




The white clip on rod is a common failure point.

AGENT 86

Was this test performed with the blower module removed. When it goes back to full hot, is the motor doing it, or is it falling to that side. Your quote doesn't make it very clear.

corvette95

check vacuum at programmer...... that is just for air direction..... blend door motor..is it right up under passenger foot area with four or five wire connector going to it? How do you get to the screws holding it on?

engle1147

I'm not sure where you are with the troubleshooting.

Can you see or hear the actuator motor running at all?

Is the "white clip" on your actuator still attached to rod/actuator?

You really shouldn't be able to move the blend door motor armature by "hand" since that thing has a gear reduction inside the housing....so this sounds like trouble to me. Those acutators are discontinued items and it is pretty hard to locate a "good used" replacement as those things are a major pain in the *** to remove/install. If your actuator is still good I'd look into inspecting and/or resoldering the electronic components within the programmer itself as mentioned by Agent in post number 2.

corvette95

I checked the door with the blower resister out. It doesnt move but isnt "stuck" as they sometimes do. It defaults to hot, no motor action at all. R and R'd 3 control heads.... no change, just pulled temp actuator....seems to be frozen. Rod and clip were fine and attached. Now I need to find an actuator, they are discontinued and Vette2Vette are out.

SunCr

If you haven't, try jumping it to power (battery)/ground first. Harness leads should be Tan/Black & Yellow. It should move in both directions when you switch the jumper wires. If it works, it's in the Supply and since you've swapped out Programmers, etc, it's the wires or the connector which you can verify by checking the Pinouts for voltage/ground.

corvette95

Did not try that, I opened up the actuator to see if I could relube it or something...lets just say its dead FOR SURE now!

AGENT 86

If you read the electrical schematics, you would see that it does more than control vacuum, such as controlling the temp door.

SunCr

Opps! You might still check the Programmer Pinouts, but obviously you'll need a new/used motor.

-=Jeff=-

My old 89 had a similar issue.. turned out to be the programmer ( 2 burnt resistors)

corvette95

I called myself reading the factory manual and only saw voltage to the actuator. How does the programmer affect actual cabin temperature other than recircle and direction????

AGENT 86

The programmer sends power to the temp door motor. It controls both directions of door.

corvette95

Thanks for the help, I am trying to find a actuator, I feel confident that is the problem, but thanks agent86, if I am wrong, I will know its the programmer, you told me something I didnt know (the programmer send voltage to actuator not control head)

SunCr

There is a return voltage (5 volts) to the Control Panel which is used to calculate Door Position. The Control Panel on these Years was the Processor - unlike the '90 and up which moved that function to the Programmer.

As I far as I know, the motor wasn't exclusive to the Vette, so if a boneyard has a Caddy or Olds with Electronic Air, an Actuator from either might work.

corvette95

thanks! I am having trouble finding one

RWDsmoke

The gears were stripped on my 86 actuator. Early 90's Cadillac had the same actuator motor but it is built into the programmer. I took the motor out and installed it into the corvette actuator case.