Automotive Air Conditioning Information Forum (Archives)

Irish on Wed April 29, 2015 3:29 PM

Year: 2009
Make: chevy
Model: impala
Engine Size: v-6
Country of Origin: United States

Finally got warmer in Chicago. At Easter I tested AC and blew fine and cold. Used it last weekend. Blew cold but made thumping noise -seemed to be from behind glove box. Continued after car turned off. Only does this when use AC. As a young girl new to Chicago and I do not have a trusted mechanic. Any thoughts?

Dougflas on Wed April 29, 2015 5:47 PM

Can you hear the noise if you open the hood? You may be hearing the equilization of the system pressures that is completely normal.

Irish on Wed April 29, 2015 6:14 PM

Thanks for the reply-this is not normal. When I called my father-it could be heard thru my phone while I was speaking. Sounds like a slow moving fan blade hitting something. It is loud and a new sound.

Jag987 on Wed April 29, 2015 7:23 PM

Was the key turned all the way off to where it could be pulled out or just the engine turned off? Sounds like maybe the bearings in the blower motor have gone out.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

Irish on Wed April 29, 2015 8:10 PM

Again thank you. Yes the key was out and same noise while running. Also-if blower motor why only with air and not the heat?

mk378 on Wed April 29, 2015 8:38 PM

Could be a stripped gear in a blend door motor. When you select different modes on the control panel, little motors behind the dash move to re-direct the air flow.

Dougflas on Wed April 29, 2015 10:13 PM

Quote
Originally posted by: mk378
Could be a stripped gear in a blend door motor. When you select different modes on the control panel, little motors behind the dash move to re-direct the air flow.
Exactly why I asked if it could be heard with the hood opened.

Irish on Wed April 29, 2015 10:28 PM

Thanks for the idea. any guess on how big a job to get fixed? Parts and labor?

paclx on Thu April 30, 2015 3:01 AM

Anything to do with blend motors for the HVAC system is a big job, and expensive unless you tackle the job yourself. On my Range Rover the official procedure to access the blend motors is to remove the entire dashboard! There are shortcuts, and the appropriate forum for your vehicle would be the best place to start. If it makes you feel any better, this is not an uncommon problem with most cars. The more technology they build into them, the more there is to go wrong.

Irish on Thu April 30, 2015 6:18 PM

Anyone agree? Disagree? comments? Other forums I should try?

TRB on Fri May 01, 2015 5:34 PM

Might see of MACS Lists anyone close to where you are at for service.

http://www.macsw.org/imis15/MACS/Resources/MACS/Resources/Resources_Main.aspx?hkey=dafb3a46-0bcd-4581-9316-4ed009cda5c4


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GM Tech on Fri May 01, 2015 9:27 PM

I just did a stripped actuator replacement in a 2008 Impala yesterday-- noise is more of a clicking noise-and even did it with car off and keys in pocket-- bought the actuator at Autozone- $35- actually not hard to do- you have to decide which one it is- mine was on driver's side I believe there are four actuators and all are the same part number.

Very common issue--- next most common failure is the door lock solenoids.....cheap china stuff in both failures..

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......