playbass

Yup, it's that time of year.

Last year, I suffered from intermittent a/c. Once my XJ would get up to the temp, the a/c would go warm.

This spring, I'm going to be looking into the air gap on my Sanden compressor. I downloaded the literature on how to do that.

My question is regarding how/when my compressor should be kicking on. Right now, it only kicks on for a few seconds at a time when I engage the a/c. Same thing with my electric fan; I know it is supposed to come when the a/c is on, but it never continuously runs. It (the fan) stays on only for a few seconds at a time when the a/c is on. Is this the correct behavior? I don't know very much at all about a/c systems, so I don't know what the proper behavior is (other than putting out cold air...)

Thanks!

NewJerseyXJ609

All the info you need is right here!

Thank CCKen when you see him around he's the one who shared this with me. It's written out as an instructors journal but it really does point you in the right direction.

http://www.askamechanic.info/askamec...nt/view/73/47/

NewJerseyXJ609

I can tell you just by the info that you have given that your systems pressure is too low. The clutch will kick in and out and if too low the aux fan won't even kick on at all.

playbass

Do you think the air gap on the clutch could be causing this (the link you gave builds up to that) or does this indicate I need a recharge?

I noticed that this past winter, if it was really cold and turned the defroster on, the compressor sometimes would not kick on at all.

DFlintstone

I re-chrged mine with LP (Liquid Propane). Did a "wet" (that's upside down) charge, with oil left from a Napa kit in the line when I opened the valve. Some amount of oil went in along with the propane. No idea if I have the correct amount of oil/refrigerant, but it works.

Not at all suggesting anyone else should do that, but mine works. Not strong, but works.

I guess ambient propane pressure is around 80 psi? Maybe I gave it close to that. Anyway you can mix what refrigerant was in my 90 with LP and it works.

CCKen

This data is for a 2000 or 2001 XJ. The OP has a 1998 XJ, which has a different A/C High Pressure Switch system.

As mentioned, the OP's system looks like it needs to be serviced.

NewJerseyXJ609

Well I tried! Haha

I figured 97-01 would be the same, should have known. Sorry bout that op.

kennzz05

[QUOTE=playbass;2384121]Yup, it's that time of year.

Last year, I suffered from intermittent a/c. Once my XJ would get up to the temp, the a/c would go warm.

This spring, I'm going to be looking into the air gap on my Sanden compressor. I downloaded the literature on how to do that.

My question is regarding how/when my compressor should be kicking on. Right now, it only kicks on for a few seconds at a time when I engage the a/c. Same thing with my electric fan; I know it is supposed to come when the a/c is on, but it never continuously runs. It (the fan) stays on only for a few seconds at a time when the a/c is on. Is this the correct behavior? I don't know very much at all about a/c systems, so I don't know what the proper behavior is (other than putting out cold air...)

Thanks!


since you live in utah i assume its cold out when you are running the a/c? ambiant temperature has everything to do with runtime for the compressor, when its cold there is little load on the system and the lo side pressure will go below the thereshold setting of the lo pressure switch very quickly, thereby shutting off the compressor and e-fan, once the pressure again rises above the cut in pressure on the switch it will again cycle on. (comp. and e-fan togeather) when its below freezing the freon sitting dormant in the unit will be below the cut out setting because its so cold out and will prevent the comp from coming on at all. So in summary you really cant tell anything about the system in this weather, it has to be warm enough out to justify using the a/c to really figure out whats going on with it.
as far as the air gap you can jump out the low pressure switch on the receiver with a paper clip and see if this makes the compressor stay on. that would eliminate the air gap as being the issue. do some googleing buy some harbour freight gauges and adapters and get an accurate idea of whats going on internally

CCKen

kennzz05 is spot on.

Here's some data that may assist.

Select a small paperclip to fit the Low Pressure Cycling Switch connector pin sockets. Do not shove a paperclip in the pin sockets if the wires are too large. If required, hammer the ends of the paperclip flat so they fit the pin sockets snugly but not expanding the pin sockets too much.

The AC Servicing tool can be obtained from any auto parts store like O'Reilly Auto Parts.

In the Temp/Pressure chart note that the Evaporator Inlet Pressure at Charge Port progressively gets lower as the Ambient Air Temp gets lower.



AC Srevicing tool.



Low Pressure Cycling Switch jumper installation and AC Servicing Tool Servicing Port attachment location.



Jumper the Low Pressure Cycling Switch, Connect the AC Servicing tool to the Service port, select AC with the mode selector **** as shown, start the vehicle, the clutch should pull in and the radiator fan should run. If the pressure gauge on the serving tool shows zero pressure, shut down the engine immediately. No pressure indicates the Freon charge is too low and the Compressor may be damaged by operating it without the proper amount of lubricant in the Freon charge.

playbass

Thanks everyone, especially CCKen and kennzz, this is great information.

It did turn cold again here in Utah, but last weekend it was 70+ degrees and I tried my A/C with the same results as I was experiencing last summer, so I was hoping to get ahead of the game and fix my unit before the heat comes in strong in a couple months.

playbass

I picked up a AC Servicing tool. At the low pressure port, when the engine is on and the A/C is on full, the compressor kicks on and the clutch engages. The psi cycles between what I assume is high and low, it starts at 10psi and then builds up to 50psi and then the clutch disengages, the pressure drops and the process starts again. It's about 80* here in Utah today.

What is this telling me about my A/C system?

I replaced both the high and low pressure switches this week.

playbass

I added some R-134a+ and the pressure started to stabilize around 30psi and the compressor stayed on for much longer periods of times. As an added bonus, the air in the cabin is cold now.

I still may have a clutch air gap issue, and I'm guessing I have a leak since it was nearly empty of refrigerant, but thanks everyone for your help. I'm making progress.

highmileage

NAPA used to carry some stuff called "freeze twelve", all it amounted to was propane and pg oil. Worked well in R-12 systems but if you had a leak "KA-BOOM" was a possibility.
Addressing the possible leak in the post the 25$ish stop leak(two part) works well but make sure the system is close to a full charge before adding, It can seize the compressor if there is not enough freon. Also it will not fix compressor front seals. It works if needed but you need to find the leak and repair it if possible.

playbass

An update: I ended up buying a new clutch face plate off of ebay as the old one was in rough shape (it was worn down unevenly on the back and kind of bowed inwards.) It would still disengage after some time or would start to squeal real bad. You find replacement faceplates on ebay for about 35$ and the one I got was brand new, and it came with some shims.

The belt squeal ended up being because my belt wasn't tight enough for when the a/c was engaged with a full charge. *duh*.

Currently 105* today in Salt Lake City and the a/c was working good for the 45 minutes I was driving around town. Hopefully it lasts, I think there are still some small adjustments to the belt and/or # of shims to get it really working great.

Now the only problem is coolant temp creep with the a/c on... zj fan clutch is this weekends project.

djb383

We did our a/c overhaul 3 years ago (new compressor, dryer, orifice tube and hose/manifold assembly). After a complete system flush and adding PAG oil, had a shop pull a vacuum and recharge the system with 20 ozs (or whatever the under hood sticker says) of refrigerant......the compressor seldom cycles off. We get slightly cooler vent temps than the chart shows......like upper 30s at the center vent in 90+ ambient on max/recirculate.