[crypto]

Tonight I'm replacing the compressor and dryer in my XJ. There's really nothing wrong with the compressor itself, but the compressor's clutch bearing is out, and the clutch itself looks pretty worn. With those two in mind, it's simpler just to replace the whole compressor.

So, with that in mind, here's my plan:

Pre-work: drain any oil from new compressor, and replace with new PEG oil.

1. remove old R-134 from system.
2. replace compressor
3. replace dryer
4. pump down system to vacuum
5. add rest of oil, refill with R-134 to spec charge.

My main question is "how many grams of R-134 is the right amount?"

My gut says "2 cans worth" but that may be too much, and I dont want to slug the compressor.

Aside from "flushing all the lines with solvent to remove all the old oil" is there anything I'm missing here? I'm not going to flush out the old system, mainly because the A/C is running fine as it is, with no leaks (so no moisture in the system)

[SilverXJ]

How are you removing the old coolant?

[Stumedic]

If you're only replacing the compressor, drain the old compressor and replace the same amount of new oil into the new compressor-make sure to drain the new compressor first. Also make sure you drain the oil from the compressor inlet and outlet and add that to your total. The idea is to replace the amount of oil you removed. If you flush the system that another story altogether. Since the system is intact I see no need to flush the system or replace the dryer. The freon capacity is 20 oz. Stu

[AZ Jeff]

According to the shop manual for the 2000XJ, when replacing the compressor, you measure the amount of oil that is removed, and reinstall the same amount. (That's real useful info---NOT).

The whole system holds 6.1 ounces of SP-20 PAG oil.

I agree with Stumedic. If your system was working fine, and only had a bad clutch, then don't both with a new accumulator. If you DO decide to replace the accumulator, you will need to add 3 ounces of oil to THAT when you install the new one, per the FSM.

[tangofox007]

Originally Posted by crypto

With those two in mind, it's simpler just to replace the whole compressor.

It's actually a lot easier to replace only the clutch.

[crypto]

Well, actually, replacing the clutch involved unbolting the compressor anyway, so I'd have access to the front of the pulleys, then using a whole crap-load of specialty tools I didnt have (pin wrench, pully pullers, etc etc) to get the clutch off, then shimming the new clutch to make sure it was within spec and getting it all lined up. All things considered, it's a lot more complicated than replacing the whole unit.

When you consider that the cost difference between the clutch assembly and the compressor was only about $30, it made sense to pull the compressor completely. Besides, when I tried pulling the clutch off last time, I could see the felt oil seal on the front of the compressor was full of oil anyway, so the compressor was probably within a year of going out.

As far as removing the R-134a, I pulled it out with my pump, which has an accumulator tank in it, until it was down to about normal pressure. Then I cracked the seals on the compressor, and stuffed the lines with rubber gloves to keep them from getting too much air in them.

I had to buy a new drier/accumulator to get the warranty on the compressor, but I ended up not installing it because I absolutely could not get the old one off at the evaporator fitting at the firewall. There was a little metal clip that popped off, at which point the accumulator should have slid out of the fitting ,but it just didn't work out like that. I turned and yanked and pulled on the accumulator until I was afraid it would break the brazings on the evaporator, and then I ceded defeat and just hooked it back up.

I only poured a few ounces of PEG-100 into the compressor (maybe 3), because most of the oil was still in the old accumulator.

I pumped it down to vacuum, and then refilled with a can and a half of R-134 in it (18 ounces), and I have an outlet temp of 38F.

So far I'm satisfied that the repair went as well as I could manage in my garage, but I wish I had been able to get the damn accumulator off.

[AZ Jeff]

Originally Posted by crypto

Well, actually, replacing the clutch involved unbolting the compressor anyway, so I'd have access to the front of the pulleys, then using a whole crap-load of specialty tools I didnt have (pin wrench, pully pullers, etc etc) to get the clutch off, then shimming the new clutch to make sure it was within spec and getting it all lined up. All things considered, it's a lot more complicated than replacing the whole unit.

Except for one KEY THING---you had access to a vacuum pump, and therefore were able to refill the system yourself. Probably 98% of the guys on this forum DO NOT have a vacuum pump, and therefore have to pay someone else to evacuate and refill the system for them. In that case, putting in a new clutch (which avoids all that) makes sense......

[tangofox007]

Originally Posted by crypto

Well, actually, replacing the clutch involved unbolting the compressor anyway, so I'd have access to the front of the pulleys, then using a whole crap-load of specialty tools I didnt have (pin wrench, pully pullers, etc etc) to get the clutch off, then shimming the new clutch to make sure it was within spec and getting it all lined up. All things considered, it's a lot more complicated than replacing the whole unit.

A proper compressor replacement requires that the accumulator be replaced. The fact that you were not able to accomplish that part of the task might suggest that compressor replacement is more "complicated" than you want to acknowledge.

[ottomobile1]

Originally Posted by crypto

I had to buy a new drier/accumulator to get the warranty on the compressor, but I ended up not installing it because I absolutely could not get the old one off at the evaporator fitting at the firewall. There was a little metal clip that popped off, at which point the accumulator should have slid out of the fitting ,but it just didn't work out like that. I turned and yanked and pulled on the accumulator until I was afraid it would break the brazings on the evaporator, and then I ceded defeat and just hooked it back up.

i'm assuming you used one of these to push the spring back in the fitting, yes? http://www.mytoolstore.com/kd/61059.jpg


all i did was slide that tool in there and a little yank let it loose without much fuss.

[pahefner01]

Originally Posted by AZ Jeff

Except for one KEY THING---you had access to a vacuum pump, and therefore were able to refill the system yourself. Probably 98% of the guys on this forum DO NOT have a vacuum pump, and therefore have to pay someone else to evacuate and refill the system for them. In that case, putting in a new clutch (which avoids all that) makes sense......

You can rent a vacuum pump at Auto Zone and get a full refund when you return it. Zero cost to you.

[AZ Jeff]

Originally Posted by pahefner01

You can rent a vacuum pump at Auto Zone and get a full refund when you return it. Zero cost to you.

That must be a local thing. The AZ's out here in Phoenix DO NOT have loaner vacuum pumps. I have asked at several stores here. Fortunately, I have a friend in the trade who does......

[tangofox007]

Originally Posted by pahefner01

You can rent a vacuum pump at Auto Zone and get a full refund when you return it. Zero cost to you.

Not where I live. Plenty of Autozone stores; no vacuum pumps.

[gjs76]

Originally Posted by AZ Jeff

Except for one KEY THING---you had access to a vacuum pump, and therefore were able to refill the system yourself. Probably 98% of the guys on this forum DO NOT have a vacuum pump, and therefore have to pay someone else to evacuate and refill the system for them. In that case, putting in a new clutch (which avoids all that) makes sense......

do you know what it takes to take out the compressor clutch on a 96 cherokee
what kind of pulley puller or extractor tool do i need and where do i get one?

[AZ Jeff]

Somebody on this forum has posted, in the recent past, a link to the Sanden service manual. Sanden is the maker of your compressor.

If you PM me with your email, I can send you the manual sections that cover the compressor clutch removal.

[tangofox007]

http://www.sanden.com/support/pdf/sd7servicemanual.pdf