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Hello all... I have a 99 C5,auto climate control.. I have noticed even when the blower indicator on the control unit shows full, its not producing the volume it should. If I happen to hit bump, it will then blow like a hurricane for 5 minutes or so and then slow back down.
Any ideas or a starting point for checking? Bad blower motor? Bad motor regulator? Bad controller (This was supposedly refurbished
)
Thanks in advance!
Last edited by DaytonaRacer; Aug 31, 2023 at 10:10 PM.
Have you verified that, when the mode is set to dash vents, that all the air flow is only coming through the dash vents and not the defrost and heater? There have been a number of posts where low air flow has been mistaken for a mode door vacuum problem.
The fan speed on Auto going fast after a bump sounds like a loose electrical connection in the control module that adjust fan speed automatically with temperature. You say the control module was refurbished? That makes it more suspect.
The air does sometimes blow out of the top and bottom vents as well as the dash.. When the air speed picks up, it still comes out the same areas.. just at a greater volume.. Some times it just comes out the dash vents, so if it was a vacuum leak, it would be consistent, plus I do not hear any vacuum noises coming from behind the intake, or in and below the battery tray. No signs of battery leakage. It does not happen every time a bump is hit.
isn't there 3 parts to the blower?.. The blower itself,a control board mounted to the blower, then another component behind the blower assembly? (voltage regulator)
If a vacuum leak would cause a consistent airflow problem and if those other 2 electrical components could not be the cause, then I'm leaning to the issue being in the AC control unit...
I'm dealing with the same issue on my 2000. Speed doesn't change but air blows thru all the outlets regardless the mode setting. Have you tried calibrating the blend door actuators? Are you getting any hvac error codes?
Also see here. The blend doors are electrically controlled but vacuum operated. A break in the vacuum would not generate an error code but a faulty solenoid would.This is courtesy C5 diag
According to the diagram, I should be able to access the air inlet door after the blower motor is removed? correct?? I need to check that actuator...it may be stuck on just outside air.
According to the diagram, I should be able to access the air inlet door after the blower motor is removed? correct?? I need to check that actuator...it may be stuck on just outside air.
If I'm not mistaken yes but only the passenger side. The drivers side requires dash surgery
According to the diagram, I should be able to access the air inlet door after the blower motor is removed? correct?? I need to check that actuator...it may be stuck on just outside air.
I do not think you will find that the air inlet door will be the cause of your problem. There is some difference in maximum airflow between the two settings but it is not as noticeable as you describe. One of your earlier posts describes air flow coming out of the heater and defrost vents intermittently. This is not normal and suggests you have an issue with your vacuum source, vacuum reservoir, plumbing, or a leaky vacuum actuator.
I have done some testing.. When I change the mode, the air changes from dash to floor to windshield depending on the setting.. tho, when on dash setting, there is some "bleeding" thru the floor and windshield vents. The reason I asked about the fresh air intake, as that does not seem to change. Seems to be stuck on outside air. So a bad actuator may be the cause there.. The blower speed that sometimes goes into "Hyper" mode when a bump is hit is puzzling as it does not occur each time.
If the air inlet actuator is sticking or otherwise intermittent it will have a similar effect to blower speed. In recirculate mode the fan is both pulling air out of the cabin and blowing it back in, where with fresh it’s only pushing air into a semi-sealed box.
Blower Motor changes Speed
