A knocking sound my be heard from the engine at times with the air conditioning on. The cause could be the AC compressor itself, if that is the case there is an updated AC compressor to correct this issue.Google+
Car Problem Reports
Dodge Avenger Knocking Noise From the AC Compressor
Dodge Avenger Problem
Average Mileage: 85,286 mi (32,000 mi - 310,000 mi)
Visitor, 2008 Dodge Avenger, 104,236 mi
I hear a knocking noise that seems to be coming from the under the glove compartment. I only hear it when i turn on the air conditioner. So frustrating since i just replaced the alternator, pulleys and serpentine belt. What else is going to go wrong with this car....its only 4yrs old.
Visitor, 2008 Dodge Avenger, 175,000 mi
Knocking noise happens after I turn off the heat or air conditioning... Goes away after a few knocks but is annoying and load when it happens ...
Visitor, 2008 Dodge Avenger, 117,846 mi
When the a/c is on it is fine. A loud knocking noise starts when you turn on the recirculate button on the a/c. Eventually it will quit. Sometimes it makes this noise when the a/c is turned off. Turn it on and it quits.
Visitor, 2008 Dodge Avenger, 64,000 mi
I hear a knocking sound from the dash when I turn on the heat/AC. Noise only last a few seconds.
terrible knocking and clatter from front of engine compartment. replaced all pulleys and tentioners, new power steering pump, new alternator, NOW they are telling me in the aC compressor. Is this a common preoblem with the 08 avenger?
Visitor, 2008 Dodge Avenger, 86,453 mi
I get a loud knocking noise when I turn the A/C and or heat on or off. It knocks/clicks for less than a min, but is very annoying. I have not brought it in to a shop yet to see what the problem is.
Visitor, 2009 Dodge Avenger, 55,000 mi
i have a loud knocking noise behind my ac uint also
Visitor, 2008 Dodge Avenger, 109,372 mi
Noises from the engine were heard, took the car to Dodge tecnician and was advised that A/C Compressor was damaged. Estimated cost of repair was $800.00!
Visitor, 2008 Dodge Avenger, 108,000 mi
Clicking noise behind glovebox when the heat/ac first comes on. Happens periodically when running ac. Also happens when the car is not running, no key in ignition.
Visitor, 2009 Dodge Avenger, 86,000 mi
Same as others. Knocking sound under glove compartment. Heard that it is the AC compressor and may cost hundreds to repair!