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air conditioner hums and shuts off

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Having a sporadic problem(worst kind).

When CCT sets on hot day(75+). I start the motor, ac starts up and usually after a short delay, goes into ac overdrive mode putting out a lot of cold air to cool quickly then back to normal ac cool air. Now every other day or so, I crank it up, ac comes on but instead of going into overdrive mode with ac, I get a humming sound from center console and after a minute or so, ac shuts down completely. No air out of any vent. When it is humming, I can feel the humming when I touch the consule. After about 30-45 minutes of the ac shutting off, turning on with hum, shutting off, it will come on normal mode, cool and continue to work normal. Also noticed the defroster will not work when ac shuts of(maybe normal)? I am getting really cold air when it is working.

I know one day it will give up completely and of course it will be 110 degrees.!!

Anyone had this or related problem?

Please advise,


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Thanks for pointing me in that direction. I dropped the cover under the glovebox but left the fan in. Today it happened again. I felt the fan and the vibration is definitely coming from there. Saw a couple pics on dropping it so I will dig them up and do it today.

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dropped the fan, Works good on bench. Oiled, cleaned and put back. Works ok on normal cool. Just when it kicks into high speed for max cool, it still vibrates, or somrthing does. Can that still be the fan that acts up when going into high speed??

Please advise if you know.


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I did change the filter. A bit of crude and a few bugs in there.

Is there an auxiliary booster fan on the 2006 CTT ac?

I am only getting the problem when it sets in sun and heats up a lot 80+outside). As I start it, the ac starts, cool air starts blowing, then the blower kicks into "boost" mode blowing a lot of cold air. Runs that way for 30 seconds or so then the hum begins. cool air still comes out for a bit but not "boosted" as before. After a couple minutes of that, the whole ac starts shutting down and starting up with the hum and less air until the inside gets cooler. Then the ac runs fine.

I am somewhat puzzled about the boosted air flow. Could the 1 fan have an accelerated speed?



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  • 3 weeks later...

Hmmm Something similar happened to me today! It was 36 degrees Celcius. I put the AC on Auto with temp at 19.5 and it worked for a few seconds on the max air out put and all of a sudden it quit working but there was normal air coming out through the back seat vents. As soon as I manually reduced both left and right air flow in the front the AC started working again but the coolness was not as powerful as it usually is. I was very upset. After parking the car 30 minutes later and swimming I went back to the car a couple of hours later and the AC was working fine on AUTO. I did hear a wierd noise from the engine compartment when all this began!!!! I hope it doesn't happen again.

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Roli- when I heard the humm, I could feel the vibration by touching the center console. Hope you do not have the problem but mine seemed to start as yours did. Would do it one time and go away for awhile. The got to the point of every time the ac called for really cold air and fan full blast. Got service in a couple weeks. Will have them check it out.

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  • 1 year later...

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