2003
Chrysler
Town &Country Limited
3.8L
122,000 miles

07/21/2009 TROUBLE FINALLY CLEARED

In addition to faulty information about the correct oil charge, the after market pressure transducer sensor, which I used to replace the original defective unit, was ALSO DEFECTIVE! I ended up having to let a Chrysler Tech use their computer and an original Chrysler part to clear the trouble. The sensors were reporting 500psi to the control unit.

THANKS to everyone who helped me with this.

WillG

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ORIGINAL TROUBLE HISTORY

The original compressor had a catastrophic failure. I removed the compressor, opened , flushed (w/Flush and Clean) and then purged (with dry air) all lines and both evaporators. NOTE: The initial flushing looked like aluminum paint. I cleaned the rear expansion valve, installed a new front expansion valve and filter-drier. I also replaced a leaking discharge line from the comp. to the condenser, installed a new condenser and flushed it also. Note: It took 7 qts. to clean everything. I also installed an in-line pan-cake filter in the liquid line before the new filter-drier (just in case there was any debris left). I drained the new compressor and put 5oz. PAG46 in the filter-drier and 8oz. in the compressor (13 oz. total). I rotated the compressor 10 times to clear the pump. I vacuumed the system for 15 min. and let it sit overnight and had no leaks. I purged the system with R134a and then pulled a 2 hr. vacuum (Robinair 15434 pump). Then I partially charged the system with liquid R134a from a 30# cylinder. I started the car and began to finish the charge with gas.

NOW THE TROUBLE: The high side was very erratic, climbing to between 300-500 psi and the pressure relief valve operated several times, discharging oil and gas. I suspect too much oil in the system, but according to the compressor manufacturer and a NAPA chart, the specs for this car are 46 oz. R134a and 13 oz. PAG46.

ambient temp: 97
front evap temp: 75
rear evap temp: 78
low press: 60 psi (before it cuts off due to HP)
high press: 300-450 but it will fluctuate and will climb to 500 and shut down the comp

I weighed the 30# can on a digital scale.
start: 35#
now: 32#
I didn't complete the charge because of the HP trouble. That's only 36oz, not the specified 46oz.


(This post was edited by WillG on Jul 21, 2009, 11:23 AM)

This truck uses a 2 speed cooling fan so the pressures can be very deceiving. I suspect you may not be getting high speed and therefore not getting it full of refrigerant either.

Double check you fan speeds and see what is going on there. That may have been the cause of the original failure also.




78 Corvette Pace Car For Sale-18k mi orig-Florida

Fans appear to be working OK.

Original failure was apparently caused by very slow oil leak in discharge line fitting (aluminum to rubber) closest to the compressor.
The unit slowly ate itself up.

Will

No, I don't believe that was the problem. Test your fan and make sure you see 2 specific speeds. Normal speed won't cut it on that system.




78 Corvette Pace Car For Sale-18k mi orig-Florida

OK, Ill re-check the fans.

Thanks

Looks like it could be a cooling problem like Hammer has suggested... My gut reaction was you've overcharged it. I don't really care for the method you used....very easy to overhcharge a system. The 1lb R134a cans are 12 ozs but there are actually 16 ozs in a lb, so even by your method you are a little overcharged.....If in fact it was only 48 ozs that went in.

One thing I do if I suspect a cooling prob is to hit the cond with water, if it brings the pressures lower than what it should be & starts cooling then you have a cooling problem if they are still to high then it's overcharged or the cond is restricted. With all that metal in the system & considering how small the condensor passages are these days that could also be possible.....

Just curious why you didn't replace the rear expansion valve.... won't cause your problem but as a complete of a job you did it just suprised me......

If I'm in a situation where I can't accurately meter the freon I just start off slow & go by pressures & vent temp...... As long as you know what the head pressures should be in relation to the ambient temp, your good...........

THANKS for the help!


THE TROUBLE WAS I put in too much oil.
I started over and re-cleaned everything. I installed the CORRECT oil 6.43 oz charge per Nippondenso,. The compressor supplier finally admitted that their information, which showed 13 oz oil, was incorrect . I purged the system with dry air, vacuumed, tested for leaks (none), re-purged with R134A, re-tested for leaks, pulled a 2 hr. vacuum and re-charged with approx 2.6# - 2.8# (as close as possible with my scales) R134A (the underhood decal spec is 2.69 #). I drove the car for about a 40 mi. test run and decided to re-check the pressures because the front evaporator temp was only 62º. The HP & LP were about 55/215-250 psi., so I reduced the pressures slightly by slowly discharging some R134A.
NEW PROBLEM: Now, the compressor clutch will not engage unless I jump the A/C clutch relay. With the relay bypassed, the system appears to be OK, 40-45/180-200psi w/52º at the front evaporator with ambient temp of 87º. The fuse and relay are OK and I replaced the pressure sensor that feeds the power control module which operates the A/C clutch relay. Can the power control module be reset or re-booted and how? Or, am I at the dealers mercy for testing/reprogramming/replacement?