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Haven't had an issue with the A/C since I replaced the blower motor a couple of weeks ago....( only short trips blows great, cools fine ) well fast forward to today, and I take a trip up to KC, and sure enough thirty minutes into the drive the A/C stops blowing....still a little cold out of the vents, but no fan. Doesn't matter what I do with the controller, auto, or try to over ride, and put the fan on high, it will not blow. Turn it off for 5 minutes, and it will start up again..on a 95 degree day, this just doesn't cut it.
So I tend to go back to what was worked on last......the stupid stealership put a new controller in, and they said they had to go through three of them before they got a good one......I'm thinking this one is heating up and going fubar too? What say ZR-1 gurus?
So I tend to go back to what was worked on last......the stupid stealership put a new controller in, and they said they had to go through three of them before they got a good one......I'm thinking this one is heating up and going fubar too? What say ZR-1 gurus?
Well, my time-honored opinion is if the dealer used up three before they found a "good" one, something else is taking out the controller. Or the controller is not the problem at all. Or ... who knows? And I hate intermittent electrical problems as much as anyone.
What year is the vehicle? I'm assuming from your description this is an automatic AC, not a manual one. Let me know, and I'll study the FSM for a while.
It's a '90 with auto air......yeah it sucks, becasue it's kind of hard to duplicate too.....but it is consistant
Thanks for any help
Couple more questions: Does the car have or ever had an aftermarket alarm system? Is the factory wiring intact, or has some other electrical cobbling been done - example: aftermarket sound system, gauges, etc.
I'm not casting aspersions here but just looking for some root cause.
Couple more questions: Does the car have or ever had an aftermarket alarm system? Is the factory wiring intact, or has some other electrical cobbling been done - example: aftermarket sound system, gauges, etc.
I'm not casting aspersions here but just looking for some root cause.
Before the accident, car was very much intact not cobbled up at all; no aftermarket alarm stuff; factory wiring ok
Originally Posted by 8388
Did you follow the link I gave you and put it in diagnostic mode?
Not yet, just found that problem is still present; it does not present itself on short trips.
Originally Posted by -=Jeff=-
Controller meaning controller head unit in cabin?
yes
so if I understand it, the Ac still runs, but the fans stops or slows..
Did you check the fan module?
No, but that certainly sounds like a good place to start
Looking at FSM pages 8A-66-0 and -1: There are three major components:
1. heater and AC control head (where the push buttons reside)
2. heater and AC programmer (not sure where this is but probably under the dash)
3. blower power module (on the top of the blower housing under the hood). This is a 4 terminal solid state device which may be the intermittent problem. I've heard of complete failures too. It's a common part - L98 and LT5 - and should be easy to find at NAPA or ACDelco.
I vote for replacing #3 since it is just sitting there on top of the blower plenum under the hood, is cheap and a 10 minute job. After that it gets harder and more expensive. I also understand it is something that fails. I can send a photo of it if you PM me your email address.
Looking at FSM pages 8A-66-0 and -1: There are three major components:
1. heater and AC control head (where the push buttons reside)
2. heater and AC programmer (not sure where this is but probably under the dash)
3. blower power module (on the top of the blower housing under the hood). This is a 4 terminal solid state device which may be the intermittent problem. I've heard of complete failures too. It's a common part - L98 and LT5 - and should be easy to find at NAPA or ACDelco.
Did they replace #1 or #2?
They replaced #1
Originally Posted by Peter Mahr
I vote for replacing #3 since it is just sitting there on top of the blower plenum under the hood, is cheap and a 10 minute job. After that it gets harder and more expensive. I also understand it is something that fails. I can send a photo of it if you PM me your email address.
I'll get you the addy
Thanks.
The worst thing is I have to take these nice long cruises to present the problem............and they usually involve at least one triple digit blast
Haven't had an issue with the A/C since I replaced the blower motor a couple of weeks ago....( only short trips blows great, cools fine ) well fast forward to today, and I take a trip up to KC, and sure enough thirty minutes into the drive the A/C stops blowing....still a little cold out of the vents, but no fan. Doesn't matter what I do with the controller, auto, or try to over ride, and put the fan on high, it will not blow. Turn it off for 5 minutes, and it will start up again..on a 95 degree day, this just doesn't cut it.
So I tend to go back to what was worked on last......the stupid stealership put a new controller in, and they said they had to go through three of them before they got a good one......I'm thinking this one is heating up and going fubar too? What say ZR-1 gurus?
When the problem occurs taking some voltage measurements will help
identify where the problem is.
There is a 4 pin and 2 pin electrical plug on top of the evaporator housing that plug into the Blower Control Module.
Verify the connectors are making good contact.
The 4 pin connector is called C2
The 2 pin connector is called C1
C2 (Four pin connector)
Pin A Purple wire is the output of the Blower Control Module and
goes to the Blower motor. Voltage will vary from 4 - 12 volts DC
depending on what Blower speed the Heater/AC Control Head is requesting.
Pin B Dark Green/Yellow wire comes from the AC Programmer and is
a varying DC voltage 2.5- 7.0 volts DC depending on what Blower
speed the Heater/AC Control Head is requesting.
Pin C Black wire is ground.
When the problem occurs measure what the voltage is at C2 pin B the
Green/Yellow wire.
Then measure what the voltage output of the Blower Control Module is.
C2 Pin A Purple wire.
You can use C2 pin C Black wire for ground for the measurements.
If you manually increase or decrease the fan speed, the voltages should
vary.
When the problem occurs, if the input voltage on the Dark Green/Yellow
wire does not change when you change fan speeds, or is below 2.5 volts,
it could be the AC Programmer.
The service manual suggests using a Tech 1 to eliminate the Control
Head.
A new Blower Control Module is around $120.00
GM #1571642
Last edited by Hooked on Vettes; 05-31-2011 at 12:32 PM.
To the original poster, did you ever solve the issue? I had the exact same problem with my C6 and just replaced my blower motor at the recommendation of a shop. Haven't had a long enough drive to try to replicate the problem again, but just found this thread and was curious what the fix was for you.
I realize this was a decade ago but you are still active on the forum. Tried to PM you but it wouldn't let me.
Still relevant... did you read the part about PMs not working? Would be good to close the thread with the fix instead of leaving anyone searching for the solution to this problem hanging.
Whew..........man let me think about this for a bit.............that was about three cars ago and I've slept a lot since then..............I think what I finally determined, was that the fan was actually blowing, but the system was freezing up and turning to a block of ice that the fan could not blow through. That is why it would self correct after a few minutes of off time, it would thaw out........I had tried a different refrigerant in the system...maybe freeze 12? I probably changed refrigerants and got this condition straightened out.........I know the new owner has taken a cross country summer trip in it, and I don't think he reported any problems.
Still love that car
Last edited by WydGlydJim; 05-20-2022 at 09:18 PM.
Wow... Sounds exactly like what's happening to me. On one occasion, literal bits of ice came out of the vents like a chunk had been loosened up and it started blowing cold again. Think the wrong refrigerant was used when my AC compressor was replaced? Seems hard to mess up with a C6 but I could see it happening on a car that came out before the newer refrigerant type was commonly used.
Wow... Sounds exactly like what's happening to me. On one occasion, literal bits of ice came out of the vents like a chunk had been loosened up and it started blowing cold again. Think the wrong refrigerant was used when my AC compressor was replaced? Seems hard to mess up with a C6 but I could see it happening on a car that came out before the newer refrigerant type was commonly used.
They can freeze up for several different reasons..........low, wrong refrigerant, compressor issues, high/low pressure sides not evened out properly...................a good A/C man should be able to figure it out.
They can freeze up for several different reasons..........low, wrong refrigerant, compressor issues, high/low pressure sides not evened out properly...................a good A/C man should be able to figure it out.
Thanks for the ideas. I drove it in weather over 90 degrees this weekend and it kept blowing the whole time whereas before I replaced the blower, air would only trickle out after 20-30 minutes. It wasn't ice cold the whole time but we weren't sweating in the car so I guess that's all you can ask for on a hot day.
05-29-2011, 03:48 PM
Well crap blower motor didn't fix it.....
