A914MAN

My A/C system is virtually flat on charge, so I'm getting everything together for a re-charge with R12. I'm not converting refrigerant at this time. I'm fortunate to have access to enough R12.

I know it's good to change the receiver/dryer, but what else?

Valve cores?

O rings?

I'd prefer to leave as much as possible undisturbed.

Soliciting sound, experienced advice

Earlydays

It's highly likely that you have a leak in the evaporator (the most common leak area) after all these years. Though if the recharge lasts a summer and you have enough R12 to recharge every year it's the easiest path....once you run out of R12 then you'll have to bite the bullet, I did.

cobalt

I would run a vacuum on the system overnight to get any impurities out. It will also let you know if you have a bad leak or a small one.

You can buy cheap vacuum''s for A/C work from HF cheap that will do the job. R12 is not cheap. I don't now what to do with all the r12 I have left over from the days when my cars had it.

griffiths

Replace the drier.
If you have time replace every o-ring in the system, you can look at the Porsche PET or Porsche's online classic site to see where all the o-rings go. Usually schrader valve cores become loose.

If you are recharging you already know you have leak(s). Other than the dreaded evaporator, check for signs of oil film around the expansion valve, the hoses attached to the front condenser, the bottom of the condenser, around the compressor manifold, and the hoses at the compressor; most of the system uses aluminum tubing.

With leaks it possible the system has lost refrigerant oil, if you are using R12, add 2-3 ounces mineral refrigerant oil or Ester oil

The best way to find leaks is with an electronic lead detector (system charged and running), sniff every joint, and then the vent outlets and condensation drain tube from the evap box.

abarthguy

Sage advice above !!
I have his new style evaporator in my '92 Carrera with R12and it works VERY well !!

mystert

I am in the same boat, bought my car two years ago with no previous records and want to get the AC system working again. Assuming it will not hold a vacuum and has a leak, what is the best way to determine the leaky components? I have a electronic leak detector I can use to sniff for refrigerant but nothing that can detect a vacuum leak. Is it OK to pull a vacuum on the system and charge it with a single can of R134A to leak check the system? I don't plan on running the compressor just checking for leaks. I don't have the time or budget right now to replace the evaporator if its bad, but if its an easily accessible o-ring, condenser, or the compressor I'm going to fix it. Once I have leaks fixed and the system is sealed I plan on removing the condenser and flushing the oil, replacing the receiver/dryer, and emptying the compressor and refilling with the proper ester oil. Does this sound reasonable or will the short term R134A/mineral oil/possibly moisture mix severely damage my AC system? Is there an alternative way to find leaks without charging the system?

mystert

Finally got around to charging my AC yesterday. I pulled a vacuum on it for 3 hours the night before and charged it up as per the Porsche TSB with 840g of R134a (840g=29.6oz = about 2.5 12oz cans). I ran it for a bit with the rocker panel and inner fender liners off(front and back). I also didn't have all the ducting in the bumper 100% installed. I checked for leaks and needed to tighten one or two fittings. Vent temps were roughly 50F and the outside air temp was about 75F. My pressures were 20F and 200F and the line running in the rocker panel was frosted over and the hose in the engine compartment had condensation on it. Is this normal? I'm assuming the high high side pressure was due to the condenser not working 100% because the air ducting wasn't installed. Maybe I put in too much oil 4.5oz? Nothing drained out of the condenser or the dryer when I took them off. I got about an oz total out of the compressor and from the connection in the rocker panel under the door. I'm assuming theres probably a leak in the evaporator and Ill address that this winter or next summer when I have the motivation to take it all apart.

griffiths

High side of 200 @ 75F is not to bad, 180 is the bogey

mystert

Is the frost on the line a normal occurrence that Ive never noticed before? Is it happening because the condenser isn't working at its highest efficiency due to the ducting not being assembled yet?

cobalt

Frost is usually a sign of a low charge.

griffiths

There is frost because the temperature on the surface of the line is at or below 32F, and there is moisture in the air.

The 20 PSI low side is interesting, either you have one very cold evaporator core or for some reason
the evaporator core is running a tad on the lean side. I believe somewhere you should have an evaporator freeze sensor? You could pull some codes or raw data off your AC control head and review that sensor

mystert

Ill button up the condenser ducting in the front and try to pull codes this weekend and report back.


I have zero history on the car other than what I have done to it. What I have found/done so far-


Car has 993 heater control. I rewired the connector on the back to work correctly as per Tore's instructions.
AC compressor didn't engage when AC buttons pressed.
No sign of R134a conversion sticker or updated fittings.
Pressing the Schrader valve on the low side initially made a slight hiss and when I pressed it a second time it didn't. System was completely empty
No oil came out of the dryer or condenser.
Approx 1oz of amber/brown oil came out of the connection under the drivers door and the compressor. That's 1oz total.
Replaced all easily accessible O-rings with upgraded green O-rings. I didn't change the O-rings for expansion valve or anything else in the "suitcase"
System held vacuum overnight as measured on AC gauge set
Reused original condenser
Replaced dryer, fan ballast resistor, foam around condenser
Filled with 4.5oz of ester oil as per Porsche TSB. 2-3oz in compressor, .3 oz in dryer, rest in condenser
Filled with 2.25-2.6 cans of R134a.

wallra

before you waste any money replacing parts I would vacuum it down to see how bad it leaks and just recharge the system and see how long it last. I would'nt waste any time or money before I did this. On my car it did'nt even hold a vacuum for five minutes.

mystert

Mine holds vacuum just fine. Longest I've measured it is overnight. Did that first before I got started.

mystert

How can you get realtime values using the laptop scan tool? When I connect to the unit it just shuts everything down and reads the codes. I have code 16 and 44. The 44 is for the secondary rear blower that's not there on a 964 and 16 is??