Heater Temperature Door Erratic
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
Heater Temperature Door Erratic
I'm getting no heat at all on my '94, it blows cold or ambient temp. I took a look at the temp door through the evaporator housing by removing the sensor that bolts in there and it closes completely or almost when temp is set to auto and 60 degrees but when set to 90 it won't close all the way and just moves slightly back and forth continuously. Do you think the problem is in the AC Programmer, C68 control unit mounted in the dash, or the temp door motor? When I press the up/down arrows on the C68 I get -00 and pressing the middle button twice still gets me -00. Also I recently replaced the heater core and everything worked fine before this, could the door motor possibly not be aligned correctly with the door shaft? What do you guys think?
Last edited by dan6712cc; Mar 29, 2009 at 04:49 AM.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
I'm getting no heat at all on my '94, it blows cold or ambient temp. I took a look at the temp door through the evaporator housing by removing the sensor that bolts in there and it closes completely or almost when temp is set to auto and 60 degrees but when set to 90 it won't close all the way and just moves slightly back and forth continuously. Do you think the problem is in the AC Programmer, C68 control unit mounted in the dash, or the temp door motor? When I press the up/down arrows on the C68 I get -00 and pressing the middle button twice still gets me -00. Also I recently replaced the heater core and everything worked fine before this, could the door motor possibly not be aligned correctly with the door shaft? What do you guys think?
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
Push both the up and down arrows at the same time for approx 5 seconds...release 00 should appear...then press the "auto fan" button once and release you should be able to read the code...that is assuming the lights were flashing when you started this procedure. Check for codes while the fault is present do not cycle the ignition switch.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
Just tried it again I get -00 when the up/down buttons are pressed then it turns to 00 when the auto fan button is pressed once. The flashing lights don't come on right away though but the erratic door swinging does when the temp is set to 90.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
Hmmm...well it's been 2 years since I repaired mine...I THINK I had a code 24..which led me to the temp door motor (one of the gears inside the motor was cracked causing the door to sorta bounce/move slightly).. once again DO NOT check for codes until the lights are flashing. Hope I've helped and not just confused the issue.
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Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
Hmmm...well it's been 2 years since I repaired mine...I THINK I had a code 24..which led me to the temp door motor (one of the gears inside the motor was cracked causing the door to sorta bounce/move slightly).. once again DO NOT check for codes until the lights are flashing. Hope I've helped and not just confused the issue.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
The codes would be stored though from last time it flashed, the only reason I don't think it's the gears is because it only moves back and forth when the temp is set to 90, if its set to 60 it will close all the way, or almost all the way, and stay there without the erratic movement.
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
So has anyone else had a similar problem.... still don't know which part is at fault since the C68 isnt giving codes...only other things I can think of are the AC programmer and the motor itself (or motor alignment)... any other input on this?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Tech Tips - if you can get it to work, I can't - will give you the procedure to pull up the Data Stream. You might do that and then post the numbers. I'm going to guess that the Programmer is sensing full heat at 90 (it'll be a numerical expression in the data stream) and as suggested, that points to a stripped gear. See what numbers you get and post them.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Tech Tips - if you can get it to work, I can't - will give you the procedure to pull up the Data Stream. You might do that and then post the numbers. I'm going to guess that the Programmer is sensing full heat at 90 (it'll be a numerical expression in the data stream) and as suggested, that points to a stripped gear. See what numbers you get and post them.
Not sure if this what you want but will post it
http://www.corvetteactioncenter.com/...agnostic+Codes
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
Yeah tech tips hasn't worked for a while, hope that gets fixed. I checked the C68 unit with the up/down arrows while it was flashing and I DID get a code, 01. This is TEMP DOOR MOTOR CIRCUIT FAULT. I don't know what that means, what part in the circuit is it referring to? Also another thing I noticed is if I put it on auto and change the temp to any setting the fans go to zero and never change unless I do it manually. Does this help at at with the diagnosis?
Last edited by dan6712cc; Mar 29, 2009 at 03:22 PM.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
Yeah tech tips hasn't worked for a while, hope that gets fixed. I checked the C68 unit with the up/down arrows while it was flashing and I DID get a code, 01. This is TEMP DOOR MOTOR CIRCUIT FAULT. I don't know what that means, what part in the circuit is it referring to? Also another thing I noticed is if I put it on auto and change the temp to any setting the fans go to zero and never change unless I do it manually. Does this help at at with the diagnosis?
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
I'll say this once more and then won't post on this thread again... your problem sounds just like mine...which was a defective TEMP DOOR MOTOR...you need to remove the passenger side lower dash panel...the motor doesn't look like what you may think a motor looks like...it's approx. 3/4 of an inch thick----3 & 1/2 inch long and 2 & 1/2 inches wide--it attaches to the bottom of the heater box and has one electrical connector---it's up very close to the fire wall and yes you have to stand on your head to remove it...the temp door itself may be binding in the heater box... but at this point I'll bet on the temp motor itself being bad.
However the temp door motor still doesn't explain why the fans don't turn on when it is set to auto (or any setting actually), they stay at 0 unless manually moved up or down.
Last edited by dan6712cc; Mar 29, 2009 at 06:07 PM.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
I know I said I was done--but--to answer your "auto fan" question when the system does not see movement in the potentiometer (built into the temp door motor) it does not allow the auto fan function...but does allow manual fan control .. once again exactly the way mine reacted to the bad temp door motor.
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,455
Likes: 2
From: East TN
I removed the motor, managed to break just about every pin on it too (the ones for the connector), probably when I was sliding the passenger side panel in. Anyways I opened it up and the motor is rusted to hell, even if this part was not at fault it would soon be gone as the motor shell is almost completely rust. I hooked it up to a 12V source and it would turn one way fine then reversing the leads it tended to make one of the gears slip up and not turn all the way sometimes. Kind of what the door was doing, but I don't know if that is because the motor didn't have the top on (so I could see the gears) or if it just became defective. I'll know for sure next week when the new part comes in.
