Diagnosing A/C problems - help requested

[BananaDan]

Hello all.  I was hoping some of our resident mechanics can help guide me here. On my way out to Carlisle in my '05 Jeep Liberty, I lost my A/C. Here are the symptoms I have experienced.

1. When A/C was first lost on the highway, it would come back and work whenever my speed would get down to under ~50-55mph. (I suspected the A/C compressor clutch was failing?)

2. After about an hour after this initial failure, whenever the A/C would intermittently blow cold it would have a terrible chemical smell in the air.

3. When the trip was done and I was no longer at highway speeds, I was then able to hear a grinding sound (sounds like metal on metal) under the hood. I would hear it with the A/C button off, and when the A/C would be turned on it would get louder. (I suspected this would be a bearing failure of some sort on the compressor, or still maybe the clutch?)

4. Now, a week later, there is also the typical squeal sound from the serp belt. The A/C no longer blows cold at slow speeds, or ever for that matter, and I don't notice the chemical smell anymore.

I am going to attempt to fix this myself and replace the belt while I'm at it b/c I can't recall changing the belt since I've owned the Jeep (~80,000 miles). My question is, how do I diagnose the problem exactly? I suspect I need to replace the A/C compressor clutch and/or the compressor itself but at ~$200 each, I'd prefer to replace only what I need to. How do I diagnose which component is the problem, the clutch or the compressor itself? Obviously I know I'll need a refrigerant recharge afterwards.

Also, the bad chemical smell concerns me. What could cause that? Could I have a refrigerant leak elsewhere, or can the clutch or compressor going cause refrigerant to leak out and cause the smell?

[Pete in NH]

Hi Dan,

Sorry to hear you're having the troubles you are and that it happened on the way to Carlisle. I suspect as you do the initial problem was the compressor clutch. As they wear, the clutch gap increases to the point the magnetic field can't hold it fully engaged. Then you start to get the intermittent operation you experienced. They start to slip and when that happens friction builds up a lot of heat. When things get really hot it's hard to know what will happen next beyond burning up the clutch assembly, it is possible the front seal in the compressor could have been damaged.

Rock auto lists a new compressor kit for your car from Four Seasons, a new compressor, accumulator dryer and liquid line with new orifice tube for $255. Stay away from rebuilt compressors, some are okay and many are junk. The first thing I would do is put an A/C gauge set on it and see if you still have R-134A in the system. If the front seal blew the R-134A will be gone. You can borrow or rent gauge sets from auto parts stores, call around. If you can post a picture of the compressor it may be possible to get an idea of what happened. In General though, it's not worth putting a new clutch on an old compressor. In the long run, it's less expensive to replace both as a new assembly. If you do still have R-134A in the system it will have to be recovered before you start to replace parts. If you want to repair this yourself , I can step you through things. I've been doing my own A/C work for years. One repair and you can pay for the tools required rather than paying a shop.

[BananaDan]

Thanks Pete. I just watched about an hour of YouTube videos and now I feel like I stayed at a Holiday Inn Express last night. I'm likely going to get the compressor and receiver/dryer kit as I've read/heard that you are supposed to replace the rec/dryer whenever you replace the compressor. Question though, how do I know if I should replace the condenser? Obviously if it's ratty and has a leak, then it needs replacing. But at $40 should I just do it since I'm replacing everything else, or is it safe to leave it assuming it doesn't have a leak?

[BananaDan]

It's definitely the clutch, it looks like it's cooked. I watched it try to operate and when the A/C is turned on, it tries to spin but just jerks a few degrees at a time. That should mean the electrical side is ok and it is a mechanical issue. PepBoys and AutoZone wanted way too much money for the parts (I was hoping to do the job this weekend) so I'll be ordering on Rock Auto. Thanks for the tips so far. I noticed a lot of black powdery dust everywhere around the pulley. I assume that's the friction material on the clutch having worn off?

I'm still curious what the cause was of the terrible chemical smell that was blowing through the vents when it failed. Would that have been refrigerant?

[Pete in NH]

Dan,

Good move staying away from Auto Zone and PeP Boys for a compressor. If I were to order from Rock Auto i would order the compressor kit with a new not rebuilt compressor.

There is  no friction material on the clutch, its steel on steel, the black power is likely ground up fried steel. The oder may have been burning belt material or worst case the compressor seal blew and it was burning oil and refrigerant.  When you get the belt off, try to spin the inner hub of the clutch by hand. If you can't spin it the compressor has likely seized up.If that happened, it likely ground itself up internally from lack of oil after the seal blew. If the inner hub spins you'll know the compressor is likely intact internally. You'll be replacing it anyway, but, you'll know the system isn't clogged up with ground up compressor. If the compressor is locked up, get a new condenser as well as you can't flush out the ground up compressor from the condenser.

Look under the hood of your Jeep for a decal telling you how much refrigerant it holds and what weight. of PAG oil you'll need.  You'll want extra oil to install the new compressor as you never know what type and how much oil is in a new compressor

[BananaDan]

Thanks Pete. Yes, I have heard the advice about going with a new part. I ended up ordering from Amazon, I found a setup for $70 cheaper than Rock Auto.

http://www.amazon.com/gp/product/B00JXYF4OQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

[beedees]

Be sure to flush everything.

[69wannabe]

Oreilly's has a can of a/c flush that has a hose that has a nozzle that you can put to your condenser and your evaporator core and usually one can will flush out the condenser and the evap core. I just done a 2000 jeep grand cherokee about two weeks ago and it's doing good. Replaced the compressor, accumulator, and the orfice tube and flushed out the evap core and condenser then blew them out good with compressed air. Always put pag oil on the new o-rings and there is a web site you can go to that will tell you how much and what kind of oil to use in the system and how much freon to put in the system. It's an experience the first time you do an a/c job but after doing two or three it get's alot easier!!! When you get the new compressor on and the new accumulator and orfice line on it and all the lines hooked back up you will need to pull a vacuum on the system to pull all the moisture out of the system and if the system holds a good vacuum then more than likely it will hold freon without any leaks. You tube is a good place to learn how to do job's like this!!!! If you ordered a four seasons compressor it will have instructions that will tell you to put half of the recommended oil into the compressor into the suction side and the other half in the accumulator suction side. Most are 6 oz and I put 3 oz in one and 3 oz in the other and once all the hoses/lines are hooked back up you will need to turn the compressor about 10 complete turns to pump oil through it to keep it from oil locking when you start putting the new freon in it.

[Pete in NH]

Dan,

Be careful about You Tube advice, like everything else on the internet there is good information and really bad information.

I looked at the link you provided on the compressor kit. The original compressor on your Jeep is a Sanden. At the price level of that kit, the compressor is likely a clone Sanden. If, as I mentioned the old compressor self destructed and there is debris in the system, replace the condenser. Also, reviews of that kit stated the wrong expansion device was sent in the kit. You Jeep has the orifice opening in the liquid line so you have to replace the entire line. A little factory cost cutting move that costs big time in the field when repairs are needed. If the compressor failed internally you will need to replace that line as there is no way to clean it out. The little auto store flush cans really don't develop enough pressure or fluid volume to be able to flush a parallel flow condenser. It takes a pretty high class flush system to do that.

As I mentioned the next thing you really need to know is did the compressor come apart internally. A locked up/damaged compressor will burn up a clutch also.  Refrigerant mineral oil or a product called Nylog are best for lubricating new O rings. There are some concerns that PAG oil reacts with aluminum tubing when exposed to air.

System oil capacity is best determined from the shop manual. With a new compressor, accumulator and possibly condenser you will essentially have a dry system and 6 oz. sounds a little low.

Compressors are sometimes shipped dry of oil, sometimes they are filled with a shipping oil, whatever that is. I always dump out whatever in in the compressor, put in some of the correct oil, turn the inner compressor hub by hand to circulate the oil and then dump that out as well. Then I refill with the correct amount of new oil. You would also like an oil that has some U/V dye in it to help find any leaks in the future.