Eletronic climate control trouble.
Thread Starter
Race Director
Joined: Jun 2004
Posts: 13,968
Likes: 710
From: WI
Eletronic climate control trouble.
Hey my blower will not work at any speed. I checked the volts at the blower plug and that reads correct. I jumpered the blower to the battery and it works fine. I checked the control module on the evap housing and that seems to check fine per the FSM charts. Though I am a novice with the multi-meter. I also checked for draw on the battery while I was there. There is only 30 milliamps draw.
I noticed another problem along with the blower not working, the climate control will not go into diag mode. I tried several different ways of entering diag mode and none work. It will just display 00 and nothing else or do anything else. All other functions work fine, just no blower or diag mode. Is the climate control shot? Last year I checked some things with it and diag mode did work.
I noticed another problem along with the blower not working, the climate control will not go into diag mode. I tried several different ways of entering diag mode and none work. It will just display 00 and nothing else or do anything else. All other functions work fine, just no blower or diag mode. Is the climate control shot? Last year I checked some things with it and diag mode did work.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
can't get blown
You have to take the programmer out down by the gas pedal and inspect the two big resistors on the circuit board. these resistors are ceramic resistors (special) and they get really hot. They sometimes ruin the board that they are soldered to. If the circuit board is damaged, neatly solder some 18-20 gauge wires in place of the bad board flat metal that is silk-screened onto the board, or resolder these resistors in place.
The transistors they use for speed control may have gone south as well.
good luck.
The transistors they use for speed control may have gone south as well.
good luck.
Thread Starter
Race Director
Joined: Jun 2004
Posts: 13,968
Likes: 710
From: WI
Thanks, I will check the programmer. I found it in the FSM but the picture of its location is vague. Would it be best to take the digital cluster out to get it or is it behind the center section above the radio? I looked down by the gas pedal and couldn't find a box like the FSM showed.
Already jumpered the motor, it works well.
Already jumpered the motor, it works well.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You should always include the year vette you are asking help for. I am assuming its an 88 from your profile. We shouldn't have to look for what year it is.
The controller on an 88 is by the blower motor and I would first check the fuse that is by the blower motor with an ohmeter, looking at it isn't good enough. See also if there is 12v on the red wire going to the control module. With the blower controls set for some air, check for voltage on the brown wire going to the controller. If no voltage on the brown wire, then your problem is with the control head in the dash. You can remove the control head and with electrical contact cleaner and a Q tip, clean the contacts on the rear of the control head. Plug it back in and see if the motor runs. If not, disassemble the control head and unplug the circuit board by pushing in on the two side tabs of the circuit board and using the Q tip, clean the edge connectors on the circuit board and reassembe. DO NOT use an eraser on any electrical contact! If you still have no blower and the gages and ctsy/clk fuse are ok in the fuse block, then you need a rebuilt control head.
The controller on an 88 is by the blower motor and I would first check the fuse that is by the blower motor with an ohmeter, looking at it isn't good enough. See also if there is 12v on the red wire going to the control module. With the blower controls set for some air, check for voltage on the brown wire going to the controller. If no voltage on the brown wire, then your problem is with the control head in the dash. You can remove the control head and with electrical contact cleaner and a Q tip, clean the contacts on the rear of the control head. Plug it back in and see if the motor runs. If not, disassemble the control head and unplug the circuit board by pushing in on the two side tabs of the circuit board and using the Q tip, clean the edge connectors on the circuit board and reassembe. DO NOT use an eraser on any electrical contact! If you still have no blower and the gages and ctsy/clk fuse are ok in the fuse block, then you need a rebuilt control head.
Thread Starter
Race Director
Joined: Jun 2004
Posts: 13,968
Likes: 710
From: WI
jfb, I clicked the box to include my sig which has the year included (in the OP). I have always done this but I can understand that some do no have sigs enabled. I will try to get in the habit of typing my model and year.
I did a continuity test across the fuse, good idea as I just visually checked it. It's fine. I checked and got batt 12v on the red wire. I checked the brown wire with the car off and found 1.1 v and with the car on start and controls set for air, found 9.78 v. Once again everything checking correctly.
It's fixed! Guess what was wrong? When doing these tests for the fourth time I noticed the plug not going in smoothly on the blower. I looked down and sure enough one of the leads was bent down. One sec with a small screw driver fixed the problem!
I did a continuity test across the fuse, good idea as I just visually checked it. It's fine. I checked and got batt 12v on the red wire. I checked the brown wire with the car off and found 1.1 v and with the car on start and controls set for air, found 9.78 v. Once again everything checking correctly.
It's fixed! Guess what was wrong? When doing these tests for the fourth time I noticed the plug not going in smoothly on the blower. I looked down and sure enough one of the leads was bent down. One sec with a small screw driver fixed the problem!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Makes sense - you might also check for a voltage drop which can occur with a poor connection between that terminal and the wire. They're crimped, not soldered. Look for discolored and partially melted wiring. If there, take the weatherpak apart and solder or recrimp the terminals to the wires.
Thread Starter
Race Director
Joined: Jun 2004
Posts: 13,968
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From: WI
I'll give it a look over, thanks.
I am curious, why is there 1.1 v on the brown wire at the module in the evap housing with the car off?
Where is 1.1 v going? Does it get stored in the module?
I am curious, why is there 1.1 v on the brown wire at the module in the evap housing with the car off?
Where is 1.1 v going? Does it get stored in the module?
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Assuming you mean "key off", I've never seen a blower voltage with it off. Specs are 2.5 or so at "1"; 6 or more at "10"; key on. Blower signal is from the Dash Controls and the only power going into it - with the key off - is to keep it's memory alive. That draw is a couple of miliamps at best and that shouldn't be enough to generate a discernable voltage. Now if you mean "key on" but the Controls set to off, I wouldn't be surprised to see a minimal voltage as GM probably wants something circulating a little bit of air. I've never had any reason to check it. Anyhow, if you've got it when the car is off, I'm surprised you don't have a dead battery after a couple of days or maybe your meter just isn't that accurate.
Thread Starter
Race Director
Joined: Jun 2004
Posts: 13,968
Likes: 710
From: WI
Yes at key off, I thought that was odd. This is reading on the brown wire of the control module, up on the evap housing. 1.1 v key off, key on and set to air reads 9.78 v and good air flow.
My meter is really cheap, I can check with my father's. He will be stopping by soon and has an expensive meter.
I checked for a battery draw while I was there. I set the meter to amps and put one lead on the pos terminal and the other lead on the disconnected pos car wire. This read 30 miliamps, well within FSM spec.
Hope to finish up installing the headers finally.
My meter is really cheap, I can check with my father's. He will be stopping by soon and has an expensive meter.
I checked for a battery draw while I was there. I set the meter to amps and put one lead on the pos terminal and the other lead on the disconnected pos car wire. This read 30 miliamps, well within FSM spec.
Hope to finish up installing the headers finally.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Are you sure you're not reading or touching the ground wire? It's black, shared with the blower ground, and with age, it's difficult to distinguish from the Control Panel input, dark brown.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The control head in the dash receives power all the time on one wire in order to keep its memory alive. The electronic circuit supplies pulses to the brown wire and with the ignition off, there is some very high resistance in the driver circuit. Your voltmeter has a very high resistance and this allows it to read 1.1 volts. The current supplied by the control head when it is off is so small it is of no consequence to the battery. The 1.1 volts you read is nothing to be concerned about.
