88 C68 Repairs - Saved $$ thanks to Forum
04-18-2009, 11:54 PM
#1
Racer
Thread Starter
88 C68 Repairs - Saved $$ thanks to Forum
Once again the Forum has saved me some big bucks. This time it was on heating and cooling problems. I have an 88 with the C68 electronic climate control which was making me wish I had ***** and cables. The first problem I had back in January was with the controller flickering like disco lights. Engle1147 posted some info on how to fix the connections on the controller that made all the difference in the world.
http://forums.corvetteforum.com/c4-t...-for-88-a.html
Then a couple of weeks ago all I was getting was heat. After following the diagnostics in the shop service manual I determined the programmer was at fault. I searched for a replacement and it looks like a new programmer costs around $200 (give or take). I searched the archives and found a post by wildride in July 08 telling how to fix a common problem by resoldering two resisters.
http://batee.com/corvette/acrepair/c...oard/c68.shtml
That fixed the programmer. Then I discovered the temperature control motor wouldn't run. Unfortunately, I couldn't find any posts about fixing that and I also wasn't able to find a replacement part. So I took it out and decided since I couldn't make it any worse that I'd take a crack at figuring it out and fixing it. I desoldered the motor from the circuit board and took it apart. To my dismay I wasn't able to see anything wrong so I put it back together and resoldered it back to the circuit board. Then I applied 12 volts to the motor terminals sticking out of the circuit board and it moved. When I applied 12 volts to the edge connectors I got nothing. I used my voltmeter to check continuity through the circuit board paths and discovered a small break where it probably burned through. The circuit board has very little to it although it has paths and holes running all over. It basically has the motor and a potentiometer. So I found a couple holes where it looked like components should be soldered in that were on either side of where the break was. In a macgyver moment I decided to use some electrical tape and a paper clip and solder in a bridge across the gap. I used the electrical tape on the back side of the circuit board to keep my paperclip from touching other similar looking wires by covering them up. Then I bent the paperclip into the right shape and position, shoved the ends through the holes and soldered them in place. I gave it a test and tada the motor moves again when 12 volts are applied to the edge connector! woohoo! I put everything back together but hadn't paid attention to the position of the plastic arm that connects the motor to the threaded rod which moves the temperature door. Hmm, where should this point? Uhoh, just wing it. I did a small test to see if the programmer moved the motor and it did, but it didn't seem like a lot of movement. It was late and so I didn't test drive it until driving to work the next morning. It turned out I now had the exact opposite problem, all I had was cold air. I was thinking I did one or two things wrong. 1, soldered the motor in backwards on the circuit board (noticed a + on one terminal after I had it all apart) or 2, I didn't put the arm on the motor in the proper orientation. So I took things back apart and played with the door manually to make sure I knew which direction was hot and cold. I then ran the motor by alternately setting the temperature between 60 and 90 so I could see which way the motor thought hot and cold were. Good news, it was going the right direction. Next I moved the motor until It was approximately midway its direction of travel. I then moved the door by hand until it was approximately in the middle. I connected the arm to the threaded rod then connected it to the motor and held my breath. To make a long story short and hopefully help you to avoid some aggravation my car now knows the difference between hot and cold! Thanks to the forum and a drawer full of paperclips I can ride comfortably again. I wish I had taken pictures but that's one of those things I tend to think of only when I'm done and I'm not taking back apart again. I still have a headrush from being under the dash.
Thanks again Forum!
Ron
http://forums.corvetteforum.com/c4-t...-for-88-a.html
Then a couple of weeks ago all I was getting was heat. After following the diagnostics in the shop service manual I determined the programmer was at fault. I searched for a replacement and it looks like a new programmer costs around $200 (give or take). I searched the archives and found a post by wildride in July 08 telling how to fix a common problem by resoldering two resisters.
http://batee.com/corvette/acrepair/c...oard/c68.shtml
That fixed the programmer. Then I discovered the temperature control motor wouldn't run. Unfortunately, I couldn't find any posts about fixing that and I also wasn't able to find a replacement part. So I took it out and decided since I couldn't make it any worse that I'd take a crack at figuring it out and fixing it. I desoldered the motor from the circuit board and took it apart. To my dismay I wasn't able to see anything wrong so I put it back together and resoldered it back to the circuit board. Then I applied 12 volts to the motor terminals sticking out of the circuit board and it moved. When I applied 12 volts to the edge connectors I got nothing. I used my voltmeter to check continuity through the circuit board paths and discovered a small break where it probably burned through. The circuit board has very little to it although it has paths and holes running all over. It basically has the motor and a potentiometer. So I found a couple holes where it looked like components should be soldered in that were on either side of where the break was. In a macgyver moment I decided to use some electrical tape and a paper clip and solder in a bridge across the gap. I used the electrical tape on the back side of the circuit board to keep my paperclip from touching other similar looking wires by covering them up. Then I bent the paperclip into the right shape and position, shoved the ends through the holes and soldered them in place. I gave it a test and tada the motor moves again when 12 volts are applied to the edge connector! woohoo! I put everything back together but hadn't paid attention to the position of the plastic arm that connects the motor to the threaded rod which moves the temperature door. Hmm, where should this point? Uhoh, just wing it. I did a small test to see if the programmer moved the motor and it did, but it didn't seem like a lot of movement. It was late and so I didn't test drive it until driving to work the next morning. It turned out I now had the exact opposite problem, all I had was cold air. I was thinking I did one or two things wrong. 1, soldered the motor in backwards on the circuit board (noticed a + on one terminal after I had it all apart) or 2, I didn't put the arm on the motor in the proper orientation. So I took things back apart and played with the door manually to make sure I knew which direction was hot and cold. I then ran the motor by alternately setting the temperature between 60 and 90 so I could see which way the motor thought hot and cold were. Good news, it was going the right direction. Next I moved the motor until It was approximately midway its direction of travel. I then moved the door by hand until it was approximately in the middle. I connected the arm to the threaded rod then connected it to the motor and held my breath. To make a long story short and hopefully help you to avoid some aggravation my car now knows the difference between hot and cold! Thanks to the forum and a drawer full of paperclips I can ride comfortably again. I wish I had taken pictures but that's one of those things I tend to think of only when I'm done and I'm not taking back apart again. I still have a headrush from being under the dash.
Thanks again Forum!
Ron
04-19-2009, 08:27 AM
#2
Is it normal for the unit to reset itself after you stop then restart the car? I've noticed sometimes if I say have it set to 90, then stop the car, then restart, it goes back to 75 or something. I think sometimes when I restart, the thing is off.
I have also noticed sometimes when I start the car, the Hvac doesn't do anything for a little while. Like I try to adjust the temp, and it doesn't change, and nothing is blowing. Then after a minute of driving it will start blowing.
The other thing is if I have the unit set on Auto at 70, then raise the temp to 90 with it still in Auto, it seems as if it goes into defrost as the doors shut and no air blows. But it will start blowing again if I drop the temp back down to 70 or so.
So, where does it look like the problem would be, programmer or unit or both?
The PO replaced the unit a few years before I bought it. I don't know if he replaced the whole thing or just the faceplate part. I already took everything apart and cleaned it up. And I resoldered some stuff on the programmer.
Would it be a good idea to put a couple of drops of vacuum line cleaner in all the Hvac vacuum lines when I pull the programmer again to check it?
I have also noticed sometimes when I start the car, the Hvac doesn't do anything for a little while. Like I try to adjust the temp, and it doesn't change, and nothing is blowing. Then after a minute of driving it will start blowing.
The other thing is if I have the unit set on Auto at 70, then raise the temp to 90 with it still in Auto, it seems as if it goes into defrost as the doors shut and no air blows. But it will start blowing again if I drop the temp back down to 70 or so.
So, where does it look like the problem would be, programmer or unit or both?
The PO replaced the unit a few years before I bought it. I don't know if he replaced the whole thing or just the faceplate part. I already took everything apart and cleaned it up. And I resoldered some stuff on the programmer.
Would it be a good idea to put a couple of drops of vacuum line cleaner in all the Hvac vacuum lines when I pull the programmer again to check it?
04-19-2009, 10:19 PM
#3
Racer
Thread Starter
Resetting itself if definitely not normal. I know mine reset itself when I took the controller out and reconnected it, but no other time. I suppose if I disconnected the battery or pulled a fuse it would also reset. According to my shop manual there is a pink and an orange wire supplying voltage to the controller. The pink wire is only hot in run, bulb test, or start. The orange wire says it should be hot at all times and gets its power from the 15 amp ctsy/clk fuse in the fuse block. I'd check the fuse. If that's good, measure voltage between the orange wire and ground. It should be battery voltage, if not there's your problem and you'll need to figure out why you aren't getting power.
Mine usually won't start blowing right away until after a few minutes. My guess is that it's waiting for something to warm up.
You can also see if there are any codes in the diagnostic mode. press and hold down the EXT Temp button, then press and release the AUTO button. A number from 1-9 preceded by a minus sign will be displayed indicating a particular diagnostic mode. Advance teh mode number by pressing the warmer button until you get to mode number 8. Then press the cooler button to select that mode. The shop manual lists some tests to perform based on the code returned. If it's 00 then it doesn't detect any problem.
The vacuum lines control the direction of the air flow by operating various doors. If they are not changing directions I'd suspect a vacuum related problem such as a line or the actuator. According to one test in the shop manual if you have it on auto and 90 degrees the air should blow from the defroster.
Over all what you describe sounds about right except for resetting itself. My guess is you have a fuse out.
Ron
Mine usually won't start blowing right away until after a few minutes. My guess is that it's waiting for something to warm up.
You can also see if there are any codes in the diagnostic mode. press and hold down the EXT Temp button, then press and release the AUTO button. A number from 1-9 preceded by a minus sign will be displayed indicating a particular diagnostic mode. Advance teh mode number by pressing the warmer button until you get to mode number 8. Then press the cooler button to select that mode. The shop manual lists some tests to perform based on the code returned. If it's 00 then it doesn't detect any problem.
The vacuum lines control the direction of the air flow by operating various doors. If they are not changing directions I'd suspect a vacuum related problem such as a line or the actuator. According to one test in the shop manual if you have it on auto and 90 degrees the air should blow from the defroster.
Over all what you describe sounds about right except for resetting itself. My guess is you have a fuse out.
Ron
04-28-2009, 10:29 PM
#5
Resetting itself if definitely not normal. I know mine reset itself when I took the controller out and reconnected it, but no other time. I suppose if I disconnected the battery or pulled a fuse it would also reset. According to my shop manual there is a pink and an orange wire supplying voltage to the controller. The pink wire is only hot in run, bulb test, or start. The orange wire says it should be hot at all times and gets its power from the 15 amp ctsy/clk fuse in the fuse block. I'd check the fuse. If that's good, measure voltage between the orange wire and ground. It should be battery voltage, if not there's your problem and you'll need to figure out why you aren't getting power.
Mine usually won't start blowing right away until after a few minutes. My guess is that it's waiting for something to warm up.
You can also see if there are any codes in the diagnostic mode. press and hold down the EXT Temp button, then press and release the AUTO button. A number from 1-9 preceded by a minus sign will be displayed indicating a particular diagnostic mode. Advance teh mode number by pressing the warmer button until you get to mode number 8. Then press the cooler button to select that mode. The shop manual lists some tests to perform based on the code returned. If it's 00 then it doesn't detect any problem.
The vacuum lines control the direction of the air flow by operating various doors. If they are not changing directions I'd suspect a vacuum related problem such as a line or the actuator. According to one test in the shop manual if you have it on auto and 90 degrees the air should blow from the defroster.
Over all what you describe sounds about right except for resetting itself. My guess is you have a fuse out.
Ron
Mine usually won't start blowing right away until after a few minutes. My guess is that it's waiting for something to warm up.
You can also see if there are any codes in the diagnostic mode. press and hold down the EXT Temp button, then press and release the AUTO button. A number from 1-9 preceded by a minus sign will be displayed indicating a particular diagnostic mode. Advance teh mode number by pressing the warmer button until you get to mode number 8. Then press the cooler button to select that mode. The shop manual lists some tests to perform based on the code returned. If it's 00 then it doesn't detect any problem.
The vacuum lines control the direction of the air flow by operating various doors. If they are not changing directions I'd suspect a vacuum related problem such as a line or the actuator. According to one test in the shop manual if you have it on auto and 90 degrees the air should blow from the defroster.
Over all what you describe sounds about right except for resetting itself. My guess is you have a fuse out.
Ron
Though, I think I might have figured out why my controller was resetting. When I had it for a year, I think the battery was on its way out. A few times, I'd have the doors open for 15-20 minutes vacuuming, and that would drain the battery to where the lights would go out and it wouldn't start. I know one time at work, I left the inside lights on for a couple of hours, and when I went to leave, my battery was dead.
So, I'm thinking that maybe with the battery on its way out, that might have been why the controller was resetting. I know there were several times though when I went to the store, came back out to leave, and the controller reset. Maybe it was just cause of the battery dieing.
I replaced the battery several months back, but haven't driven it much since then. I know I've left the interior lights on my Firebird overnight, and it started up fine the next day.
04-30-2009, 06:24 PM
#6
I took the programmer apart and reconnected it up. Started the car, and held the programmer in the upright position.
I had it set to Auto and adjusted the temp up and down. I noticed the programmer clicked a couple of times when I went from 60 to 90. I do know it clicked when I went from 85 to 90.
When I went from 90 to 60, the programmer clicked 3 times. I do know it clickes from 85 to 90, and from 90 to 85.
So, I'm guessing that's all working fine?
And, what would be something good to spray in the resistor pack hole to clean out the HVAC system? I know mold can grow in there, and figured it would be a good idea to clean it out. I think GM has something for that.
I had it set to Auto and adjusted the temp up and down. I noticed the programmer clicked a couple of times when I went from 60 to 90. I do know it clicked when I went from 85 to 90.
When I went from 90 to 60, the programmer clicked 3 times. I do know it clickes from 85 to 90, and from 90 to 85.
So, I'm guessing that's all working fine?
And, what would be something good to spray in the resistor pack hole to clean out the HVAC system? I know mold can grow in there, and figured it would be a good idea to clean it out. I think GM has something for that.
