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Discussion Starter #1
Hello everyone.

Today I noticed that my air condition compressor makes a loud "click" sound when engaged. The engine idle speed also momentarily drops when the compressor is engaged. I took the car into the dealer (2007 Exi) and the dealer said that the loud "click" noise is not normal.
Whilst at the dealer, we also noticed that when the engine is switched off, a "hissing" sound could be heard from the compressor.
Other than these noises, the air conditioner is working.

Has anyone had a similar experience?

A worksheet has been prepared and the car is going in next friday to check the noises from the compressor.
 

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Hello everyone.

Today I noticed that my air condition compressor makes a loud "click" sound when engaged. The engine idle speed also momentarily drops when the compressor is engaged. I took the car into the dealer (2007 Exi) and the dealer said that the loud "click" noise is not normal.
Whilst at the dealer, we also noticed that when the engine is switched off, a "hissing" sound could be heard from the compressor.
Other than these noises, the air conditioner is working.

Has anyone had a similar experience?

A worksheet has been prepared and the car is going in next friday to check the noises from the compressor.
a click noise from the a/c compressor is normal, it will cycle on and off also as its running, and the rpm drop is a result of the extra load on the engine. Now, depending on how loud the click is, it may or may not be normal. the click is a result of an electromagnet engaging the a/c compressor clutch. A hissing noise ive heard before, not sure what causes that but ive never seen anything bad come of it. they may just tell you its normal, but again i dont know how Loud it is on your car
 

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^^^Well said!

It is normal depending on how loud of a click although the click is pretty loud if your not expecting it.

Let us know how you make out!
 

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I have the hissing sound too when I shut the motor off. I dont know how long it hisses for though. It was there from the day I bought it and still have it with about 825 miles. Doesnt seem to be anything wrong so it doesnt bother me. If something is wrong then Ill just take advantage of my 5/60 bumper to bumper warranty...as long as its under warranty I dont lose a single second of sleep at night.
 

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The hissing sound is normal. When the compressor is running it builds up pressure on the high side of the system and draws the pressure lower on the low side of the system.

When you shut off the car the pressure slowly bleeds off the high side into the low side through the orifice tube/thermostatic valve (depending on which the system has). As the pressure bleeds off/equalizes is makes a slight hissing sound. This tube/valve where the pressure bleeds through is usually near the firewall, sometimes even in the dash. This makes it easy to hear the slight hissing sound it makes. If you shut the A/C off while the car is running it makes this same noise, but it isn't very loud and you probably simply don't hear it over the engine, blower noise, road noise, radio, etc.

The A/C compressor clutch will click when the system is turned on. This happens in the engine compartment and is less likely to be heard since the engine is running. It can sometimes be heard if the engine is idling and you are sitting still because there isn't much other noise, but I don't think I have ever heard mine while driving. Depending on how loud it is and when you hear it the click noise may be louder than normal, or caused by something different and not normal.

Good luck. Let us know what the dealer says.
 

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Discussion Starter #7
Thanks for the information everyone. Well, my mind is at ease with the hissing sound from the compressor when the engine is off. Hopefully, the loud clicking, which the dealer says is abnormal, would be sorted out as the car is still under warranty. I will let you all know of the outcome.
Thanks.
 

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The hissing sound is normal. When the compressor is running it builds up pressure on the high side of the system and draws the pressure lower on the low side of the system.
When you shut off the car the pressure slowly bleeds off the high side into the low side through the orifice tube/thermostatic valve (depending on which the system has). As the pressure bleeds off/equalizes is makes a slight hissing sound. This tube/valve where the pressure bleeds through is usually near the firewall, sometimes even in the dash. This makes it easy to hear the slight hissing sound it makes. If you shut the A/C off while the car is running it makes this same noise, but it isn't very loud and you probably simply don't hear it over the engine, blower noise, road noise, radio, etc.
Thanks for the insight, I didnt know that.
 
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