EDIT:
I posted a synopsis of my troubleshooting/historical info in the next post

Ok, so AC had never worked in my XJ. Truthfully, it could have been drained at some point by the PO and never refilled, or it could be completely FUBAR (mechanically, visually everything looks to be in pretty good shape).

NOW, my question is - how do I proceed to get this thing working properly?
Evap core and Heater core were replaced, but I never really hooked the AC system back up. When it was charged, it would cause the Jeep to get really hot, but I can't really tell if the compressor was causing the system to heat up, or if the Condenser radiator may have been plugged up or something.


Step 1: Get the E-Fan working. I tried a new relay which didn't work, so I am assuming it is the fan/motor itself that is bad. I have not verified that by wiring it straight to the battery though. I will replace the fan and try to test it (though temps are still pretty cool in Colorado).

Step 2: New Condenser Coils/Radiator

Step 3: New Compressor?

Do I replace the AC Compressor pre-emptively? I have no real idea if it is "good" or not, but the Jeep has about 200K on it, and the AC has not been used that much

Do I need to replace the AC lines out of precaution as well??

And this is a stupid question, but how do I replace the AC condensor and lines? Does the radiator need to come out and cooling system drained? I get the general idea (remove Radiator support, unbolt condenser, remove lines, replace), but I can't find any pictures detailing the process and I would ideally like to see the procedure before I dive in.

 

Quick synopsis;

I went ahead and jumpered the low-pressure switch and the compressor clicked on (that was about 2 years ago). Filled the system with a DIY kit from AutoZone and rocked it for the summer. I did make sure to get the pressure in the "recommended" range or whatever. It held pressure for the ~2 months that I actually used it. I was born and raised in Florida so heat is pretty familiar to me

A/C Worked, but not very well. It would blow cold air initially but if I sat in traffic it was eventually start blowing warmer and warmer, until the engine temp started to creep up too high. Holding ~1500 RPM would help to dump some of the heat load out and help keep the AC blowing cool air (probably 50*F), but the E-fan didn't ever kick on and if I left the XJ idling with the AC on, it would overheat on its own.

Fast forward to ~2 years later, and I have completely overhauled my cooling system including a new heater core, hoses, water pump, t-stat, and radiator. Never creeps up past 210*F any more.
I had the AC system discharged at that time and replaced the AC Evaporator Core at the same time as the heater core, for good measure, and replaced the AC Drier since I was in that area anyways.

Parts Replaced;
- AC Blend Door
- Heater Core
- Evaporator Core
- A/C Drier
- O-Rings for AC Drier to compressor and evap core

Original Parts
- AC Lines
- AC Compressor
- AC Condenser

EDIT:
Or do I just get a shop to pull vacuum on it for a few days to make sure there are no leaks, then just fill it and see what happens? Time is short for me and I hate having to go back and re-fix things a second time. But I also hate wasting money on parts that don't need replacement, so I am not trying to throw money at the problem or anything.

 

Sounds like you have most of the bases covered. Compressor replacement is a judgement call. These Sanden compressors last a long time. When my '85 AMC Eagle bit the dust last year due to a bad transmission and rust the AC was still ice cold with the original Sanden compressor.

The problem is that when a compressor fails it typically sends debris into the system. R134a systems use a parallel condenser that you can't really flush out. If there's any garbage stuck inside the flush compound will just go around it, then the stuff may come loose and create problems later. Likewise the drier would have to be replaced, probably the expansion valve too. So you can spend $$$ on a new or rebuilt compressor or take a bit of a chance on the old one.

Typically you pull vacuum for a few hours at most, not days. (A shop will usually do it for an hour or less.) You can pick up a vacuum pump at Harbor Freight for about $100 with a coupon that does a good job, at least for occasional use. (It would probably self-destruct in constant use at a shop.)




http://www.harborfreight.com/25-cfm-...ump-98076.html

Actually it looks like HF has it on sale now for $100, so with 20% off you're looking at 80 big ones to have your own pump.
Then after pulling vacuum for a while, shut the valves on the gauge set, turn off the pump, and see if the system holds vacuum. If it does the system will most likely hold your refrigerant charge, but not necessarily. Even if it holds vacuum it may not hold up under pressure. I like to use "Nylog Blue" on the O-rings and fittings, it helps give a good seal.



http://www.refrigtech.com/Product/Se...ylog_blue.html

You might want to take this opportunity while the system is empty to replace the schraeder valves in the compressor.

You should also add some oil to make up for what was in the evaporator and drier. Might want to add some dye as well to make it easier to find leaks, especially if you don't have an electronic detector. There are rules of thumb for how much to add for each replaced component, but the best way is to drain the oil from each into a measuring cup and put the same amount back in. Either that or flush the whole system, drain the compressor, and put in fresh oil in the amount specified by Jeep.

It is best not to leave your AC system exposed to atmosphere for very long. The drier will absorb atmospheric moisture, as well the oil, and this will not come out when you pull vacuum. Moisture forms acids in the presence of R134a which can eat small holes in your evaporator and condenser.

If you're going to have a shop put in the refrigerant for you they should handle all this stuff as part of the service.

 

If your system sat for 2 years its time to have a shop pull vacuum. You could also do it yourself with the rental tools from autozone. If it doesnt hold vacuum replace as many o-rings as possible plus get a new accumulator and charge it up making sure to include some dye to find potential leaks. If it doesnt leak run it, provided the compressor is relatively quiet. You may get lucky and all will be fine. If you do decide to replace the condensor, its not difficult at all. Remove the top radiator support and if you're careful you can get it out without removing or draining the radiator. It helps to remove the battery and tray to get better access to the quick connects on the lines.

 

Holy crap, I totally forgot I made this thread (posting at work, a dangerous game )

Rambler 65 - thank you so much for the detailed breakdown!

And Brielly1 - that is exactly what I was wondering in regards to replacing the condenser (if the radiator also needed to come out). I finally have my Jeep cooling system back to 95% and no leaks, so I want to avoid poking that bear
---

I think I am going to opt to try out the stock compressor and condenser. If the compressor fails, I would need to replace both anyways so its not like I would be creating more work later on by not swapping it out right now (minus evacuating the refrigerant out of the system).

I was considering flushing the condenser core as well, but based on the same premise I might just start "cheap", see how it performs, and go from there.

This was the flush tool I was looking at, but I would rather just put the $$ towards a new condenser instead of flushing out the 18 year old stock unit.


I am going to go ahead and replace all the O-rings I can easily get to before pulling vacuum though (which I will also have the A/C shop do since I am too cheap and don't have any legitimate uses for an expensive vacuum pump). I will update this thread when I actually get the work done, right now I have some driveline grinding that I need to diagnose/fix.

I figure keep the heep moving in a forward direction, then I can think about creature comforts

 

From what Ive read, its difficult if not impossible to flush a condenser. As long as your compressor hasnt failed it probably wont be necessary anyway.

 

Yes, the parallel-flow condensers used with R134 cannot be reliably flushed out since the flushing compound may just route around any debris that's lodged in there. (The old R12 systems used a serpentine condenser, those can be flushed.)

Sounds like a good plan. The Sanden AC compressors really are very reliable. The only thing I might suggest if the system has been open to atmosphere for a long time (like 2 years!) you might want to replace the old oil with fresh and put in a new drier/accumulator. You would drain and measure the oil out of the compressor and use dry compressed air to blow it out of the condenser, evaporator, and hoses. (There are dessicant filters you can add to your air hose to remove moisture.) Then add the same amount of fresh oil back into the compressor and add enough into the other components to bring the system total up to spec.

Likewise the drier/accumulator should be replaced if it has been exposed to atmosphere for a while. (These are designed to absorb moisture and should be left exposed for as short a period of time as possible.)

Moisture is the enemy here, much more so than was the case with R12. The problem is that the oil used in R134 systems is extremely hygroscopic, and aborbs atmospheric moisture 100 times more readily than the mineral oil previously used with R12. This moisture is not released when you pull vacuum. Moisture in the presence of R134 forms acids that can eat holes in your evaporator. (That's why evaporator leaks are so common with R134.)

BTW, the flush kit you were looking at is the same one I use, it works well. Also you can make a vacuum pump for cheap from the compressor out of an old refrigerator, room air conditioner, or the like. (My main pump is on a homemade AC service cart that uses parts from an old refrigerated water fountain. I picked up the HF pump just to have something easier to move around.) With several AC-equipped vehicles to service it's nice to have this stuff handy.

 

Where in Colorado are you? Evaporators often last a long time out here because we don't use the A/C that much. Condensers get trashed from rocks and dust like our windshields. No sense in even trying to flush the condenser. Just scrap it and get another. BIf the system has been open or without any pressure for years I'd replace everything because the PAG oil used in R134a sucks in any and all moisture. It ain't like the oil mineral oil days. If you can't replace everything replace as much as you can.