QuestionQUESTION: I have a 2000 Jetta VR6 that makes a very low rumble noise intermittently when the ac is on. While watching the compressor I notice that when you hear the sound from the firewall area the compressors clutch will turn off then turn back on. This happen every 30 seconds but not all the time. The ac works fine and I have replaced both the idler pulley and belt. Any suggestions?
ANSWER: Hi there,
Have you located the general area the noise is coming from?? is it inside the car or is it in the engine compartment?? what kind of noise is it??
In my experience i have found that the Pollen filter ( located in the phlenum chamber next to the wipers or under the glove compartment) produces excessive noise when it is clogged.
does the noise disappear when the compressor switches either on or off???
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QUESTION: I replaced the pollen filter about a month ago. The sound is a low BRRR sound emanating from the firewall area and is heard at about the same level from inside the cabin. There is a slight vibration in the pedals when the sound appears. When viewing the compressor; at first no sound with clutch engaged then you hear the sound from the fire wall area and the clutch disengages for a few second then turns back on with no noise then the same thing happens again. But the compressor only turns off after the sound appears and the compressor will run noise free until the sound is heard. The compressor clutch cycles off and on every 10 to 30 seconds but the ac is cold. It seems that the noise is more prevalent when the car is hot and blower on full speed but then other times it doesn't matter what speed of blower. The car was quite filthy when purchased with few maintanence items done. Could it be related to some other duct component or freon level? Any ideas would be gratefull. Thanks
ANSWER: Geez this is a tricky one!!!
any chance of getting a diagnostic done using VAGCOM or VAS5051/2(the factory tool used by the dealer)???
Ok from what i know about the AC system employed by VW and what i can make out from your description there is something causing load on the system.
The Ac system is designed to cut off when under full load conditions like when you are under full acceleration or when taking off from standstill to provide more power that is usually used by the compressor, does this problem occur on all the ranges i.e. position 1,2,3,4 and auto of the fan or only on the auto position?? does the AC cut off when they steering is turned end to end??
could it be that the two items are not related at all?? have you carried out a visual inspection of the phlenum chamber and the underside of the car???
maybe some thing is loose and therefore rattling and the different loads created by the AC switching on and off (which reduces and increases the load on the engine )
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QUESTION: OK, I was able to do a more thorough check and discovered that the ac did not produce cold air at idle with the compressor running. I but in a few ounces of 134a and the compressor clutch would only engage for a few seconds and would no longer cool at any speed. The the compressor started discharging refrigerant from the back. Did I put to much in? I could not isolate the noise but was coming from the compressor. Any ideas?
AnswerHi Jeff,
looks like you have a fault on the AC compressor it self, the gas shouldn't have leaked out and I doubt you filling the gas caused the leak, I think it was there all along.
If memory serves me correctly there is a pressure switch located along the AC lines in the engine compartment and if the pressure in the lines is low then the system shuts off to prevent damage to the compressor.which is what I think you are experiencing.
I think its time the car was given to a AC specialist to rectify any leaks and refill it to the correct pressure. Also a diagnostic would provide more answers so if possible get one done before refilling the gas so all faults can be rectified at once.
