I've got an 05 Grand Prix that just began blowing all the a/c out of the defrost vents regardless of what position it is set on. I know some Fords default to defrost when there is a vaccumm problem, but don't know about a newer GM. Anyone have any ideas?
Air only coming out Defrost vents on 05 Grand Prix
- Thread starter nwjones18
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Which engine and is this an automatic or manual system?
The actuators in all systems are electric and may need recalibration.
Pull the HVAC control module fuse (engine off) for at least 60 sec to reset.
Its possible there is a vacuum line somewhere in the system but the diagram doesn't show any.
The actuators in all systems are electric and may need recalibration.
Pull the HVAC control module fuse (engine off) for at least 60 sec to reset.
Its possible there is a vacuum line somewhere in the system but the diagram doesn't show any.
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Its a 3800 V6 and a manual system. I will try pulling the fuse. I know I haven't been able to find any vacuum lines..
What i posted is the recalibration for your system.
I don't know anything specific about THAT vehicle. But I've had the same problem on other GM vehicles, and it's always been due to a lack of vacuum.
I had an '85 Buick Lesabre that would switch to the defrost outlets while going up hill (when the engine wasn't making much vacuum). Problem was a bad vacuum check valve.
My '94 Corsica defaulted to defrost vents only one time when my battery started leaking... and the battery acid ate through a vacuum line that ran under the battery tray. I also lost cruise control. A length of rubber vacuum hose and a new battery took care of the problem.
And there was my first car- a '78 Cutlass. Air came out only at the defrost vents when I got it (at age 16). There were two vacuum lines near the heater box that were hanging loose. I hooked them up to manifold vacuum and suddenly my heater controls worked, but there was a constant hiss under the dash. It was probably a broken line, bad switch, bad diaphragm... something like that. But I was too young and dumb to figure it out, so I just disconnected the lines and left it that way.
I had an '85 Buick Lesabre that would switch to the defrost outlets while going up hill (when the engine wasn't making much vacuum). Problem was a bad vacuum check valve.
My '94 Corsica defaulted to defrost vents only one time when my battery started leaking... and the battery acid ate through a vacuum line that ran under the battery tray. I also lost cruise control. A length of rubber vacuum hose and a new battery took care of the problem.
And there was my first car- a '78 Cutlass. Air came out only at the defrost vents when I got it (at age 16). There were two vacuum lines near the heater box that were hanging loose. I hooked them up to manifold vacuum and suddenly my heater controls worked, but there was a constant hiss under the dash. It was probably a broken line, bad switch, bad diaphragm... something like that. But I was too young and dumb to figure it out, so I just disconnected the lines and left it that way.
Pulled the HVAC fuse and that fixed it! Thanks! Nice when its an easy fix.
So no AC now, but you call it fixed?
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So no AC now, but you call it fixed?
I don't see where he said that, did i mess that in an edited post or something?
I understood his A/C is blowing cold air out of the defroster vents and nowhere else like the middle vents like its supposed too.
So no AC now, but you call it fixed?
I don't see where he said that, did i mess that in an edited post or something?
I understood his A/C is blowing cold air out of the defroster vents and nowhere else like the middle vents like its supposed too.
No I pulled the HVAC fuse to let the system reset, reinstalled the fuse and now the air is blowing out the vents as it is supposed too. It has been blowing cold all along, but was just coming out of defrost vents.
It's probably the HVAC blend door. My 1999 Buick Century makes a noise under the dashboard when you switch it from vent to defrost.
Originally Posted By: nwjones18
Pulled the HVAC fuse and that fixed it! Thanks! Nice when its an easy fix.
Here is the word 'FIXED'.
Pulled the HVAC fuse and that fixed it! Thanks! Nice when its an easy fix.
Here is the word 'FIXED'.
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