My 2007 Jeep

My Jeep makes a whining noise and sounds like a deisel truck. In the morning when I back out of my garage and reverse down a little way the noise is there. When I then drive off, the noise gets even louder. As I drive, the diesel noise seems to stop. The whining noise fluctuates. The whining noise started when my mechanic put in a new tensioner. He insists that the problem is the compressor. Twice he has removed the belt and checked everything and he says there is nothing wrong with the car except the compressor. T he air conditioner mechanic says it is not because the ac works well. He said that he has seen quite a few Patriots with this problem but he cannot tell me what it is because the people never come back to tell him what the problem was. I play the cd and the radio loud to drown out the noise so my husband who had a stroke does not have to listen to the noise.

Do you think you know what this is all about?

I do appreciate you guys. We used to listen to you on Sundays in the Virgin Islands, but your show was discontinued.
Oh boo hoo hoo,



You describe the noise as “diesel noise.” Is it because the noise has a rattle quality?

A Chrysler bulletin written for Jeep Technicians says the rattle noise could indicate the need for a newly designed Air Conditioner Compressor in some 2007 Jeep Compass and Patriot models with a 1.8L, 2.0L, and 2.4L non-turbo engine. The replacement is necessary because refrigerant slugging damages the A/C compressor housing.

Your mechanic could be correct. Most mechanics can access Technical Service Bulletins. This one is a 3 page bulletin #24-006-07.

This is a fairly expensive repair and an accurate diagnosis, perhaps by a second qualified opinion should be considered. Also, be sure to use the newly designed compressor if it’s needed.



Oops! I forgot to mention that when you post questions on this forum, you don’t get Ray of the Click & Clack Brothers, you get an assortment of random car enthusiasts who try and offer helpful advice. Some of the advice is helpful and some not so much, but see what you get and perhaps it will steer you in a positive direction.

Welcome and good luck!


Ask your mechanic if it is possible as an experiment to briefly run the engine without the compressor’s accessory drive belt on, so the compressor isn’t turning. Then you’ll know for certain if noise is coming from the compressor or someplace else.

Another idea, if the noise started immediately after the new tensioner, me, I’d tend to think it was the new tensioner causing the problem, rather than the compressor. Do you still have the old tensioner? Another experiment, you could ask the mechanic to temporarily put that one back on. If the noise goes away, then the new tensioner must be on the fritz.

This longitudinally mounted engine should be very easy to access with a mechanic’s stethoscope. It’s a device for about $25 that allows you to usually easily determine which peripheral component on an engine is making noise. You simply put the earpieces in your ears and touch the metal rod to the suspect components. A diaphragm converts the vibrations in the rod to sound waves… and viola! Be very careful, though, that you don’t stick the rod into anything spinning… or onto the electrical posts on the alternator (which should be covered by rubber caps anyway).

You Can Try This, On Your Own …

Since the dashboard HVAC (Heating/Ventilation/Air Conditioning) control engages/disengages the clutch on the air conditioner compressor and starts and stops the compressor’s operation, you possibly can determine if the noise is present only when the compressor is running and isolate it as the culprit.

Here’s how it works. With the engine running, when the dashboard HVAC control is set to A/C or Defrost settings, the air conditioning compressor starts running. Try moving the HVAC control to a fresh-air ventilation setting (not A/C and not Defrost) and see if the noise goes away or changes.

Come back here and using Leave A Comment, let us know what you find.


Mountainbike, the Patriot has a transverse engine. The car is basically a jacked up Dodge Caliber.

OP, I have an 07 Compass, same car except for the body style. All of the accessories are on a single drive belt. Have your mechanic check out the pulley on the alternator. It’s got a one way clutch in it to dampen engine pulse effects on the alternator. Mine went a couple of years ago by getting louder and louder. The sound also varied sometimes between a whine and a lower pitched vibration.

Not saying for sure that it’s your problem, but it’s worth checking out.

Oh, man, another illusion vaporized!

Well the a/c man had a second opinion by his mechanic. The man said it was the altinator. My mechanic missed it because the altinator was doing what it is supposed to do. But the noise was clearly coming from it. I took it back to my mechanic who listened carefully and concurred! Finally I had a concensus! He exchanged the altinator today and my vehicle drives like heaven. All noises are gone and the car purrs! I am so very happy that this has gotten resolved. And I thank you for your input. You were very helpful.