Noise in A/C system

[Jimmy9190]

I have a warbling/groaning type of noise in the AC system in my Dakota. The noise is not present when the heater is in use, only when the AC is on. Is it possible to get an air bubble or air pocket in the AC when the AC is evacuated and recharged? I had that done after an accident and I have had this noise ever since. The compressor is original but the body shop replaced the condensor and the receiver-drier, the radiator and the fan along with some front body parts after I hit a deer on the interstate. I am thinking maybe they didn't pull enough vaccuum when they did the AC recharge and that is why I have this noise. The noise is only audible from inside the cab; when you open the hood there are no abnormal noises from the AC compressor or other AC parts. The noise is only present when the compressor cycles. The fan and temperature control both work fine and the AC is ice cold. I am stumped and appreciate any help.

Thanks,

 

[Triple_Se7en]

I get a similar noise in my 1999 S-10 with the older style AC charging system. The noise is basically when I have the defroster or AC on when starting the vehicle. The noise can be described as similar to a noisy ADBV filter at startup. It temporarily disappeared when the fan clutch was replaced. But I'm hearing it again once in a while. It all started when I added/topped-off the refrigerant a few years ago. I'm wondering about an air bubble too.

 

[Jimmy9190]

My noise turned out be the compressor--I think. A shop that does AC work here told me that when the compressor begins to go bad the noise caused by the internal problems with it may not be audible at the compressor but the noise can be transmitted down the AC lines to the evaporator. This made sense to me since the noise seemed to originate in that area of the cab. So the shop wanted about $650.00 to change it out. I had them evacuate the system and I got a compressor from NAPA, a new accumulator from Carquest (plus a free hat!) and a new fixed orifice tube from the Dodge dealership. I changed out all the parts myself and then had the system recharged, so far it is much quieter and I don't hear that noise any more. I do hear the normal noise from the compressor cycling on and off. Altogether the job cost me about $520.00. The AC shop quoted $650.00 just to replace the compressor alone, so I think I did well with it. From what I have read online this job can run anywhere from $900.00 to over $1200.00 so I was pretty glad about that, and to do it correctly you must change out the accumulator and the fixed orifice tube.

I'd like to know if this story sounds logical to any BITOG'ers here. Sorry for such a long post.

 

[AcuraTech]

Well done my friend! Looks like you did everything for half the price. And yes, it does sound logical.

The price we pay just to stay cool! Oh, wait. I see you live in Florida. A/C is pretty much mandatory there. That humidity is killer.

I can only wish I lived in Florida, and didn't have to deal with rotten cars. That road salt is killer on suspension and brake components. The oxyacetylene torch aka blue wrench is our best friend here in the rust belt.

 

[Jimmy9190]

Thanks AcuraTech. I was hoping someone with some AC experience would respond. I'm pretty sure I did it right, now I just need a hot day to really test the AC. It's cool here now, will be in the low 70s/high 60s today but is supposed to warm up in a few days. I don't envy you or anybody up north who has to work on cars. I worked for a summer in the Service Department at a Chrysler-Jeep dealership and a guy there was from Pennsylvania and he said the same thing you did, he had to work with a wrench in one hand and a torch in the other most of the time.

Thanks,

 

[mechtech2]

You can't get an air pocket - the gas [if any] will mix with the refrigerant. Water is the real killer that the evacuation is trying to remove.
When your system is stable [like in the morning after sitting all night], check the pressure. Even a cheap fill gauge will work. Don't start the car, just read the pressure - the high and low sides will be the same . It should be about 80-90 in your climate .

This is a quick check of the system that is really helpful, and you can go from there. Then, do your running pressure tests. You will know that you have the approximate right amount of refrigerant, and then, if the compressor and system are working correctly.