ammonman

Well crap. After an extensive AC refresh this spring that saw all coils flushed inside, all new o-rings, new TXV's and drier, a compressor re-seal, and all lines refreshed with new barrier hose EXCEPT the high pressure liquid line from the drier to the front and rear AC expansion valves (yeah, that one) I have lost nearly all the charge. System has been working flawlessly since the refresh until this morning. It was a little too humid for comfort so I turned the A/C on and rolled up the windows. No cold air at all. Got to work and checked the compressor and found the clutch was not energizing. Figured the relay in my rebuilt Climate Control head had failed or the compressor clutch had gone Tango Uniform. Stopped and picked up a new relay at the Shack on the way home so as to be prepared. Checked for power at the clutch lead and sure enough no power. I stuck the A/C gauges on just to be sure I had charge and lo and behold, only 10psi left in the system. So now the hunt for the leak starts with the prime suspect being the only line I didn't rebuild because it is such a bi@tc# to get out and back in. When I did the refresh I pulled vacuum for 24 hours to ensure a dry system, then left it valved of for a further 24 hours as a leak test with no change in gauge indication ( I know, I should use a micron gauge I just can't justify the expense for occasional home use.) so I declared the system leak free and charged just under 36 oz of 134a. So tomorrow I get to go leak hunting. I hope it's a pretty sizable leak and therefore easy to find. I just am not looking forward to getting that #%@$# HP liquid line out and back in as there will be a BUNCH of stuff to get out of the way that I hate to disturb (like wire harnesses) not to mention another coolant change.

Ok, whine mode off. This is part of the joy of owning a 20+ year old Porsche.

Wish me luck that my compressor seal failed or some such.

Mike

j.kenzie@sbcglobal.net

Hi Mike,
I feel your pain. I did the same refresh this spring and so far so good. The liquid line looked like a bitch so I did not replace it either. I decided that I would partially remove it and crimp in place a new barrier hose end if needed.
My bet is some other source of leak will be found. Are you using a leak detector or UV dye, or soap bubbles? I would put my money on compressor seal early failure, but I am an optomist too.
Good luck,
Dave

OTR18WHEELER

the uv dye check would be best, just hope it doesnt look like motel 6 under the hood.

WallyP

Sniff the rear evaporator.

ammonman

I'm going to grab one of our ultrasonic listening systems from work today. They are amazing tools and very versatile. I'll drop some gas into the system and start listening for leaks. Hoping for anything other than HP liquid line or main evaporator as the source. If it turns out the liquid line is the source I'll either pay for a house call from a local AC shop or buy the tool and supplies for an in-place replacement of the hose. If the dash has to come out I guess I'll start another WYAIT list.

Wish me luck.

Mike

Mrmerlin

mike did you do anything to reseal the rear evaporator?,
the copper lines going into the aluminum is where they leak, JB weld can be used to pot the joints.

if you flushed any cleaners through the system they must be fully removed before you install new O rings,
the cleaner fluid will damage the O rings and they will leak,
any O ring not replaced should be

jcorenman

Mike, spend the money on an electronic leak detector. They work well, and won't break the bank-- around $150-200 as I recall. (Harbor Freight for half that of course...).

There's two theories... The leak is either the one hose you didn't change, or any of the ones that you touched last...
That line-from-hell is mostly hardline which will last forever, if it is leaking then it will be an o-ring at one of the ends, or the flex-line.
Once you know exactly where the leak is, then you will know what the options are.

j.kenzie@sbcglobal.net

Do not buy a super cheap leak detector. Sometimes they react to water vapor as well as freon. It is possible to suspect an evaporator leak because of it reacting to the condensation. Don't ask me how I know.
Good luck,
Dave

ammonman

I used a low vapor pressure solvent to flush the lines, then air purged and let the system stand open for a few days before installing all the new o-rings (every o-ring was replaced) then pulling vacuum for 24 hours. I am pretty confident I got all the flush solution out before I closed it up and got all the moisture afterward with the deep vacuum. I didn't do anything to the rear evaporator other than flush. I was concerned about the corrosion on the aluminum but felt it best left alone until it became a leak (sleeping dogs and all) Didn't think about the galvanic joint there so that is good to know as a known failure point. All the lines I did change were done by a local shop I've used in the past. They have the apparatus to nitrogen pressure test their assemblies before they leave the shop. Not saying they don't have a bad crimp/joint, just that those are down the list of things to check. I'm starting with the ultrasonic rig since I have the use of it for free. If I can't pinpoint the source with that I'll buy a HFC detector. We use these ultrasonic units for finding both pressure and vacuum leaks on different mechanical systems inside noisy manufacturing plants. They are great for finding vacuum leaks that hold under positive pressure. We also use them to listen to fluid flows through valves and steam traps as well as bearings in motion, corona discharge from electrical insulation breakdown, and a myriad of other scenarios. Very handy tools to have and only about $500 for the kit. can also be used to find leaks in weatherstripping and other types of seals with the included ultrasonic emitter. Close the emitter up inside an enclosure and the use the detector to sleuth out the leaking gaskets.

More to come....

Mike

Mrmerlin

dont rule out a defective schrader valve,
these are usually replaced as well as O rings

ammonman

Replaced all the Schraders as well but thanks for the reminder.

Mike

ammonman

Well, turns out the new compressor shaft seal has failed. Dumped 12oz of juice in which brought it up to about 90 psig and started listening with the ultrasonic. It was immediately apparent there was a leak in the engine bay. I quickly zeroed in on the compressor clutch/pulley and located that as the leak source. Leaking bad enough to actually feel the gas escaping. I need to go buy a lottery ticket today.

Thanks for all the feedback and suggestions. Now to get a seal and o-ring kit. Anyone have a source for quality parts?

Mike