A/C troubles

In my 99, the A/C works like a charm until I come to a long stop, where the air significantly gets warmer, like it is freezing up. I have to cut it off for about 5 minutes, then I get cold air again. Several years ago I had a part(on top of the condenser, I think) replaced via a TSB, the details are escaping me right now. Could I just be low on on refrigerant?

more than likely you're low on refrigerant, but after a check you're still having same problem make sure the condenser has adequate airflow through it. Remove and dirt, leaves, dead bodies and such from the grill and verify the electric cooling fan is pulling air through it sufficiently to remove the heat from it. Use a sheet of news paper to verify airflow-- if the fan will pull it out of your hand and hold it against the condenser, you should be ok.

I went back and looked up the TSB. It was 24-13-99 JUL 99 for A/C Evaporator Freeze up.

I don't know the newer AC systems well enough to say, but if it uses an expansion valve, it may need flushing or the thermal sensor for the evap. may have gotten dislodged (if it still uses one)

do check the refrigerant level first, though as until you know it's right, you're just guessing:dunno:

It's at the shop now getting a check and a top off, if needed.
Thanks!

MattS said:

I went back and looked up the TSB. It was 24-13-99 JUL 99 for A/C Evaporator Freeze up.

Click to expand...

Is the solution for that replacing a switch? I had a problem and a switch fixed it, like $30 for a new one at the dealer.

I don't think it was a switch. I think it had something to do with a check valve or some kind of fitting under the hood on the evap canister (I think)

Heres the one Im thinking of;

Number: 24-13-99

Group: Heating & A/C

Date: July 2, 1999

SUBJECT:
A/C Evaporator Freeze Up
OVERVIEW:
This bulletin involves installing a revised low pressure cycling switch.
MODELS:

1997 - 1999 (TJ) Wrangler
1997 - 1999 (XJ) Cherokee
SYMPTOM/CONDITION:

Intermittent low A/C output due to reduced airflow through the evaporator or excessive condensation draining from the vehicle after the vehicle has been turned off due to evaporator freeze up. The system will operate normally in most conditions. The condition will only occur after extended periods of driving with the A/C system operating. The system will return to normal operation after the NC system has been turned off long enough for the ice on the evaporator to melt.

DIAGNOSIS:

If customers complain of this condition and no other NC system problems are found, perform the Repair Procedure.

PARTS REQUIRED:

1 05015871AA Low Pressure Cycling Switch (1997 Models)
1 05015872AA Low Pressure Cycling Switch (1998 - 1999 Models)
REPAIR PROCEDURE:
THIS REPAIR IS COMPATIBLE WITH DAIMLERCHRYSLER'S MOBILE SERVICE PROGRAM AND DOES NOT REQUIRE HOISTS OR OTHER FULL SERVICE FACILITY SPECIAL EQUIPMENT.
1. Disconnect and isolate the negative battery cable.
2. Disconnect the low-pressure cycling switch connector from the low pressure cycling switch located on accumulator.
3. Remove the switch from the accumulator and remove the 0-ring.
4. Lubricate the 0-ring with refrigerant oil and transfer it to the new switch. Install the new switch. The switch should be hand tightened to the accumulator fitting.
5. Connect the harness to the switch.
6. Connect the negative battery cable.
POLICY: Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:

Labor Operation No: 24-35-35-90 0.2 Hrs.
FAILURE CODE: P8 - New Part

As posted on JF:
All three of my cars--a 97 XJ, a 2007 VW GTI and a 2006 Honda Element--have sucky AC at idle. It's a little better on the max/recirc setting. My XJ has an extended idle switch--helps immensely.

I guess that was it. It seems like I'm having the same symptoms again. I bet the dealer didn't really do the repair.

Ok, I got it back from the shop. The guy told me that the gauges read that it has plenty of freon. It is still freezing! I called the dealership and explained what is going on. They say that the only way to truly test the level is to suck it out and put it back in. They want $70 to do it. I mentioned the cycling switch, which they didn't go for, and said freon level. The switch is $40 and I can turn a wrench. Hey, $30 is $30! Is the dealer blowing smoke, or should I trust in what the guy is telling me. Keep in mind that the switch has been replaced once, maybe. Thanks in advance,

Well at least you found out which dealership to avoid. If the high and low side pressures look good, then the amount of freon in the system is within the correct range. I don't believe low freon by itself will cause freezing. It should just cycle a lot of not at all if it gets too low.

Sounds like the low pressure cycling switch mentioned is not operating properly. Actually, that might have been noticeable looking at the low side pressures. There are many articles mentioning this problem (google on the part number from above).

http://findarticles.com/p/articles/mi_qa3828/is_200606/ai_n17177105
http://www.jeepsunlimited.com/forums/showthread.php?t=898052

Despite what the dealer is telling you, your problem sound very symptomatic of a failed low pressure switch. It's happened to me...twice.

It's an easy change out. It's located on top of the dryer/accumulator, and it's wired with a plug connector. Disconnect the connector, unscrew the old low pressure switch, and install the new one.

You won't lose any freon as a shrader valve keeps things in check....

Ivan said:

You won't lose any freon as a shrader valve keeps things in check....

Click to expand...

Yup.

I attempted to change this switch on a Ford Mustang for a friend once and discovered that it didn't have a shraeder valve under the switch. It started spraying as soon as we loosened it. It had spit out the o-ring and wouldn't seal again. He wasn't happy that it dumped the freon in the parking lot. Turns out that his a/c was an aftermarket unit installed by the dealer instead of factory installed. That also explained why he had a wierd setup on theidler pulley. Lesson learned - don't get a/c as a dealer add on.

I've got the switch coming in Monday. I hope my schrader valve works!