HVAC question
Thread Starter
Melting Slicks
Joined: Oct 2010
Posts: 3,028
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From: Tollesboro Kentucky
HVAC question
My 2008 started having an issue yesterday with the blower fan.I noticed it was stuck on high so the first thing I suspected was the module.After some searching I found that you can check it by seeing if there is a voltage change while adjusting the fan speed.I get the voltage change while speeding the fan up and slowing it down.The odd thing is if I turn the fan on all the way I can no longer turn it down.As long as I don't turn it full speed I can turn it back down and up without issue.It stays an high and the only way to change it is by shutting off the car.I tried the 3 button reset to no avail.Has anyone else ever had this happen or have any suggestions on things to try?
Race Director
Joined: Dec 2013
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C6 has a blower motor controller (PWM) on the fan, that is between the HVAC controller and the fan motor itself.
https://i.ebayimg.com/images/g/lOcAA...dw/s-l1600.jpg
So since HVAC controller is doing what its supposed to do, then time to pull the motor controller apart to see what the problem is in it.
https://i.ebayimg.com/images/g/lOcAA...dw/s-l1600.jpg
So since HVAC controller is doing what its supposed to do, then time to pull the motor controller apart to see what the problem is in it.
Thread Starter
Melting Slicks
Joined: Oct 2010
Posts: 3,028
Likes: 794
From: Tollesboro Kentucky
I appreciate the response!I checked the fan by doing the voltage test that I found online.It said to check the center wire on the motor while hooked up.Should see the voltage change by adjusting the fan speed.I do get a voltage change while speeding the fan up and slowing it down.the odd thing is the voltage and fan speed doesn't change once I go to full fan speed,As long as I don't go full speed everything works fine.I thought that by it doing this the problem was in the dash control unit itself.Is there anything in the fan module that would cause this situation.Really confused on this but hey,I'm getting old!
Last edited by jamieo; Apr 28, 2022 at 05:51 AM.
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Again, PWM on the back side of the fan,and sounds to be the problem itself.
Hence at 100 percent, pretty much straight to ground for fan motor (no pulsing), and when the HVAC backs off it voltage and the PWM should be pulsing to run the motor slower, pwm is pretty much stuck bridged to ground instead.
So would pull PWM to take a quick look to see if its the timer that needs to be replaced, or something else on the board that let all its smoke out instead.
Short of that, just replace the HVAC motor since it will come with a New PWM on it.
Hence at 100 percent, pretty much straight to ground for fan motor (no pulsing), and when the HVAC backs off it voltage and the PWM should be pulsing to run the motor slower, pwm is pretty much stuck bridged to ground instead.
So would pull PWM to take a quick look to see if its the timer that needs to be replaced, or something else on the board that let all its smoke out instead.
Short of that, just replace the HVAC motor since it will come with a New PWM on it.
Last edited by Dano523; Apr 27, 2022 at 07:39 PM.
Thread Starter
Melting Slicks
Joined: Oct 2010
Posts: 3,028
Likes: 794
From: Tollesboro Kentucky
Update.Just replaced the fan with a new one and same problem.Put my old fan in my C7 and it works fine.Put the C7 fan in my C6 and same issue,fan sticks on high.Has to be the module.Don't want to take the dash and cosole apart but it could be worse.
On a side note,I did notice what sounded like the blend doors cycling while changing the fan.Car had been off for about half an hour and my remote was nowhere near the car.Coincidence or could this be related to the module als?Car seems to be drawing power all the time so I guess it's time do start doing a amp draw test.Seems like it is always something.Maybe I need to downsize and not try to maintain too any vehicles!
On a side note,I did notice what sounded like the blend doors cycling while changing the fan.Car had been off for about half an hour and my remote was nowhere near the car.Coincidence or could this be related to the module als?Car seems to be drawing power all the time so I guess it's time do start doing a amp draw test.Seems like it is always something.Maybe I need to downsize and not try to maintain too any vehicles!
