Air conditioning issue

I did a search before posting this, but to be honest I was so confused on all the posts that I read that I wasn't able to finding a starting point for my problem.

I sent my 00xj to the shop to have the cracked cylinder head replaced. While it was there I had my mechanic (3 hrs away from where I live) have someone take a look at my AC. We had charged the AC but it only lasted a couple weeks. Upon further investigation they couldn't find any leaks in the engine compartment and determined that I needed a new evap and heater core. So I had them replace it. Got the jeep back a few weeks later, turned the blower on and got nothing.. Turned it to 4 (max?) and it blew. Looks like I need a new blower resistor.

Driving to the cape this weekend i had the AC on, about 30 minutes into it I changed the direction from dash to dash and floor. 5 minutes later its blowing semi-cool air. Pulled off to get gas and opened the hood. The pipes were cool but the condensor was warm and wasn't sweating. Changed the direction back to dash and started the jeep. Blew cold air for the next 15 minutes or so before I shut it off because I didn't need it anymore.

Obviously I'm annoyed it wasn't fixed right the first time. I'd like to fix it on my own rather than going back to CT. Does anyone have any idea where I should start looking?

still having this issue can anyone help me with this?

Could be a number of things.

When it was blowing "semi-cool" air, was the compressor still engaged? How long was the engine off at the gas station in your first post? Does it start blowing cold again after you have the AC turned off for a while? Do you feel a difference in the volume of air blowing out the vents (or just the temp)?

The condenser should be warm (hot even) and won't sweat since there's no condensation on it.

Get one of the instant read thermometers and stick it in center vent. Turn AC on MAX, close windows and, once fully cold, read the outlet temp. You should also use some manifold gauges to read the low/high side pressures.

You could be experiencing evap freeze up. Possibly a blend door issue (also common).

sorry for taking a little while to get back to you. It seems like the system blows cold for a short period of time (20 minutes) and then starts to blow warm & humid air. If the jeep is stopped and allowed to cool down for a short period of time, the system will blow cold air for a short period of time and then blow warm.

No difference in the volume of air.

I remember reading somewhere about the fins on the compressor clutch and when they get warm it doesn't engage right. Does this sound like it could be the problem?

Thanks for the help.

One possibility is moisture in the coolant.
When you first start the compressor, all is well. After a short period, the cold goes away, replaced by ambient air. What could be happening, is that a small amount of water freezes the expansion valve orifice, or the opening in the orifice tube, cutting off the flow of freon. You let the system rest for a while and the orifices thaw, allowing for another cycle.
Replace the filter/dryer, have the system properly vacuumed, and recharged. The main thing, other than no leaks, is a proper vacuuming; this is what removes the moisture from the system. Anytime the system is opened to atmospher, moisture will get into it. The only way to get it out is with PROPER vacuuming.

interesting... thanks for the input. I'm guess I should also run the system till it blows warm air and then check to see if the compressor clutch is locked up or not- correct?

I struggled with the AC on my 2K WJ for two years. I determined it was the clutch after a lot of wasted effort. I even replaced the coil in the clutch,used several cans of 135 (senior moment!) and bought gauges at HB. I finally decided to read the WHOLE instruction set in the FSM.

What led me astray was the statement that if you are assembling the clutch you do not need to measure the gap between the clutch plate and the clutch. You only needed to measure it for a new clutch. I decided to measure it anyway. It was way out of spec on the plus side!

What was happening was the under certain conditions it would engage and at others it woiuld not. Just on the hairy edge of operating/not operating, probably thermally related. I took a spacer out of the assembly which moved the plate closer to the clutch putting it within spec and now I have AC all the time. Everyting works great! The clutch material wore down to increase the gap, duh after 125K miles!

Not saying this is the problem you are having, and I don't know if the 2000 XJ AC compressor is anything like the one on the 2K WJ, but you might check it out.

So what would happen is that it would engage at the begining of a trip and then after a period of time quit. I took a trip from Portland to Seattle on a 95* day. by the time we got out of the metro area, it quit. We stopped half way to get drinks, as we were very uncomfortable. Started it up and it worked the rest of the way!

BTW: an open sun roof does not improve MPG's

Emerscape said:

interesting... thanks for the input. I'm guess I should also run the system till it blows warm air and then check to see if the compressor clutch is locked up or not- correct?

Click to expand...

I don't think so. I will defer to an AC expert. If the pressure increases enough, the high pressure switch will disengage the clutch. The expansion valve is behind the dash and part of the evaporator. It would always be cold so you can't tell if it is clogged or not. If you have pressure gauges, you might see a pressure increase just before the clutch disengages. This is conjecture on my part.

sjx40250 said:

What was happening was the under certain conditions it would engage and at others it woiuld not. Just on the hairy edge of operating/not operating, probably thermally related. I took a spacer out of the assembly which moved the plate closer to the clutch putting it within spec and now I have AC all the time. Everyting works great! The clutch material wore down to increase the gap, duh after 125K miles!

Click to expand...

Based on my research (unless it was your thread I was reading) this sounds to be a common occurence. Is it hard to remove the spacer out of the assembly? Also any idea on how hard to replace the clutch? I do have a factory service manual but doesn't really give a good idea how hard it is to replace.

Thanks

It is frustrating to find what you expect to be a detailed instruction for service and then find 2 sentences! The most difficult part is keeping the clutch assembly from rotating while you remove the bolt in the middle. I use an old belt and let it wrap on itself while holding the remaing portion, kind of like a oil filter removal tool.

On my clutch, the spacer is between the plate and clutchmounting surface on the shaft. They are washers. I had two of them in there and I simply removed one. They were different thicknesses, so choose wisely!

I am not sure I was clear. Bolt - Clutch assembly - washer - washer- compressor shaft and compressor assembly.

Again, I don't know the layout of the 2k XJ. I had to remove the compressor from the mount to get clearance and improve ease of access. You don't need to remove anything to measure the gap. I used spark plug wire gap tool. A blade thickness gauge may be difficult to use as it may not be flexable enough for the thickness. Use what you have.

Hope the FSM tells you what the gap range needs to be. I suspect it is dependent on the compressor.

It may not have been my thread as I discussed this on the WJ forum over on JU.

great thanks for the info.. I've done some more research - and I found a guy on jeepsunlimited (old thread) that mentioned his clutch bearing die and shoot red dust all over the engine bay. I found a bunch of red dust next to my battery but could never figure out where it came from. I'm guess that the compressor is the source of the dust...

I'm wondering if it's best to send to the mechanic..

Maybe, only you can make that decision. The dust is normal and is clutch material. I was hesitant due to the lack of information. But, I thought, if I was careful and did not go beyond my capability I would be OK. It was way easier than I thought and actually felt embarrassed. It is pretty bad when you embarrass yourself in front of yourself only!

In my efforts all I ran into was " replace the compressor" kind of statements. Only the FSM discussed clutch and coil replacement as serviceable items. The factory parts list helped validate that they were serviceable with part numbers for the serviceable parts. My compressor is unique for the 4.7 as it mounts on the intake manifold making it's housing fit only 4.7's. Compressor assemblies are north of $400. I was not willing to spend that kind of money for what I though would be a simple problem. I was right. Please tell my wife I was right for a change!

haha. I feel the exact same way. Just found the Sandene (compressor) service guide on the internet. Gives a pretty good explanation as to how to check the clearances and adjust via removing the spacer. Going to start out by checking the clearences and going from there. Didn't really want to spend the weekend working on the jeep but it's better than paying someone else.

Thanks for the help.

I don't remember how many weekends in a row I have had to work on the Jeeps in the last 6 months. Besides my 4 jeeps, my daughter has a 98ZJ. Why did she buy one? Cheep availalbe mechanic! Good thing I have one extra to drive while one is being worked on.

Good luck!

thanks. hopefully I can fix this without bringing it to the mechanic...

That's one downside to living in the city. We sold our expedition and kept our jeep as our dd between the two of us (worst decision ever)...actually worst decision ever was selling my 03 Dodge Ram 2500 QC for the expedition.....

But living in the city just makes it harder to work on the jeep since everyone always stares and asks if I need a jump... Wish there were more jeep enthusiasts around me..

I had this issue on my 97. Blow cold for 20 mins before quitting. The clutch simply stopped engaging and I got warm air. I had an ac guy look at it and he said one of those tiny washers (shims) needed to be removed from the clutch. I can recall running this idea through naxja and didn't get an overly positive response to what the ac guy Had told me (probably gave rubbish details mind!). Anyway the ac guy was right, He removed just one of those tiny shims and it's worked great since. Not saying that's your issue but i do believe this air gap issue is a simple check to carry out that it appears gets overlooked sometimes. It took this ac guy like 5 mins to fix. He didn't remove the compressor but don't know what tools he used. I've read a few posts about this issue and people talk of replace compressor or clutch or freezing over etc. But mine was a simple fix. And I've seen others have there's cured with this shim removal. If you know how to measure the pressure and voltage then great. But if you don't, I think if I were you, I'd watch that clutch and see what happens. Establish what that gap should be, take it to a shop if necassary and get them to verify it and or remove one of those shims.
Oh yeah, just make sure you take it to a decent garage, heater core replacement is another "chestnut" that I suspect is usually not neccasirily the case, but good for squeezing some of your hard earned out your pockets!

sjx40250 said:

I don't think so. I will defer to an AC expert. If the pressure increases enough, the high pressure switch will disengage the clutch. The expansion valve is behind the dash and part of the evaporator. It would always be cold so you can't tell if it is clogged or not. If you have pressure gauges, you might see a pressure increase just before the clutch disengages. This is conjecture on my part.

Click to expand...

He has a 2000. It does not have an expansion valve, only an orifice tube in the liquid line. If any trash gets into that line, it will clog the orifice up. You can take liquid line out and back flush it with isopropyl alcohol to if anything is clogging.

Op - The problem with spacing is the magnetic field dimensitons. If the gap is too big, there isn't enough magnetic force to draw the clutch into the plate. By removing the shim, the clutch is within the field to operate properly.

Chasjr1 - thanks for the clarification. Principle is the same, a venturi.

Yeah i agree with sjx, my problem was thermal related. As the jeep heats up, the metals change size enlarging that gap just enough to prevent the clutch from getting sucked in by magnetic force to engage. That's why it worked for me for first 20 mins then died. Once everything cooled down it was back to the correct gap.

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