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Hopefully someone on this Forum has some answers or suggestions. For several years I have been struggling with my 1996 A/C system. I did a evaporator/expansion valve replacement myself using DIY write up from this forum and Pelican Parts. I must say it was a big PITA to do, but I got everything back together. A local shop evacuated the system and did a recharge. The resulting temps were rather poor. Later I rebuilt the original A/C compressor, had a shop recharge the system and again no real improvement in temperature. A year later a new attack on this issue. Went through all of the vent actuators, cleaned the internal PCB contact wipe areas, made sure they all worked as they should. Just a few weeks ago I had a mishap with the compressor and had to replace it with a new compressor. I borrowed a vacuum pump, plugged the High and Low side compressor lines and pumped the system down. When I installed the new compressor and removed the line plugs, there was still vacuum. Back to the shop where a pump down and leak check was done prior to the recharge. Still not great cooling. The Tech removed some compressor oil and there was some improvement (81 degree F ambient and 61 degree F out the center vent). The Tech felt it should be better than that. He asked if the evaporator had foam around the sides to seal up against the 'suitcase' enclosure. I did not take any pictures during my reinstall and I don't remember. Looking at the DIY printouts, I don't see any mention of foam. Looking at evaporator pictures on Pelican Parts for both Genuine Porshe and Kuehl. The Porsche part shows more foam in place. The Kuehl part shows foam along the top side and a roll of something that might be foam rolled up. I don't remember getting the roll with my evaporator or any mention of it or where it goes. See accompany pix.
I am at cross roads as to remove my 'suitcase' again to look for foam and or to apply foam all around the sides to make a complete seal so all the air moving has to go through the evaporator core. Not sure if there is any easy access to 'look' inside the suitcase.
Any thoughts, suggestions, solutions would be most appreciated!!!!!!
This Forum is such a Great source of information from so many people from around the world!!!!!
Pictures would be much appreciated. I live in Titusville, FL.
I will try and get some temperature readings once the ambient air temp goes up some and make sure the CCU settings are correct for max cooling. I really don't want to crack open the suitcase again, but not getting good cooling is driving me and my technician nuts, plus the $$$ being spent.
Always had cold ac in Orlando. The leak happened and I replaced condenser, back to cold ac.
min the pic, you can see how tight the condenser is to the opening.
With the pollen filter at the fan inlet removed you can see the face of the evaporator.
I did a Kuehl evap and it came with a foam on the top. I added a thin foam strip on the vertical faces just to be sure.
The roll is sealant that goes around where the pipes go in.
Hi Mr. Bock,
Four thoughts,
-The Porsche service information defines specifications for vent temperatures at various ambient temperatures. You may be chasing a problem while the system is within specification and is working properly.
-- Consider cleaning the Evaporator coils/fins if you didn't do this previously. Easily done with a wand bug sprayer:
See the topic on this in the middle of this page:
--If all the vent servo motors and vacuum actuators are working properly it may be the expansion valve if the vent temperatures are out of specification. Be sure to check the recirculation vacuum actuator behind the CCU in the dash.
--Finally, if the system is within specification and you simply want more cooling a modification of the ductwork so more air blows under the dash onto the driver's legs is an option. I did this on a 930 to good effect where the modification is rather simple. On a 993 it may require a little work.
Thanks Guys!!!!! I will sort through the info given and see what applies to get my ac cooler. It looks like I don't need to pull the suitcase (again) that is quite a PITA that I did to install the new evaporator and expansion valve. I will report back...
Recently did an overhaul on mine, new evaporator, condenser, expansion valve, high pressure switch, blower fans and drier. Also replaced every o-ring and seal in the circuit and fixed the vacuum recirc actuator behind the CCU. With the suitcase out I was able to check the electric servos one of which wasn't working but after a gentle tap or two came back to life. Compressor was fine and didn't need replacing.
I believe I had two leaks, a small one on the evaporator and another from a join in a pipe near the back left wheel under the side skirt. That leak in the join was very hard to find.
Prior to the fix the cooling gas would typically last around 4 months and would blow quite cool although I never actually measured the temp. Since the overhaul it's all still working OK - six months later - and still blowing cool but should be noted I don't think it is any cooler than before.
I live in a hot climate in North Queensland and summer days of 35-40C are not uncommon and even with all the recent work the system struggles. I have a late model Subaru Impreza daily driver and its' A/C leaves the 993 for dead. Let's face it, the 993 design is around 30 years old, there is a lot of glass in the cabin and it is never going to perform like a new car. It is what it is.
With the pollen filter at the fan inlet removed you can see the face of the evaporator.
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Kudos
not only see it, you can touch it all over. With thin hands, if my memory does not fail me, you could even seal it's corners with adhesive foam stripes, and test.
In my primitive logic, before I unscrew anything, I would hook a Porsche system tester, If you have access to a tester, and check the values of all temperature sensors and flap functioning.
With all the stuff you changed, I have a feeling a temp sensor is triggering the compressor clutch too often, thus no continuous cold air. Maybe the evaporator temp sensor ?
I rebuilt my A/C from the compressor to the fans. Here are few notes I would add:
First of all removing the fan motors before removing the suitcase makes the job much easier. There is lots of wire going to the fans tucked away on top of the suitcase for this. Ideally you would have Porsche Tool 9512, part number 000.721.951.20 around $125 at Sunset Porsche. Following the instructions on Pelican I removed the whole A/C harness starting at the HVAC control unit instead, a real PIA but I wanted to clean up the wiring under my dash anyway. There are methods to remove the motors without the tools here on Rennlist, if I had to do it over again I would cut the wires to the fan motors and install some Jr. Timer electrical connectors to look "stock". If you go this route Corsa-technic.com has the connectors.
I used the Kuehl condenser which is slightly taller than the Behr unit, it fits OK but is not a "direct" replacement. I used the Kuehl drier which is a bit smaller than the OEM unit.
The gasket around the perimeter of the suitcase was hard and cracked and it is 2 mm O-ring material I got from McMaster Carr described as "Oil resistant soft Buna-N O-ring cord 2 mm wide, 10 foot length". I used adhesive backed foam liberally to seal all areas around the evaporator.
I bought my compressor on Amazon it is a Denso "New compressor with clutch" # 471-1130 and cost $212. It is exact replacement and comes with gaskets to install the manifold from the OE Denso unit.
I used URO brand replacement motors from EBS Racing and they appeared exactly like the OE ones and work perfectly, $129 each.
I used Refrigeration Technologies "Nylog" assembly lube on gaskets, etc. instead of refrigerant oil and purchased all O-rings from Porsche parts department.
I sent my HVAC unit to Tore Bergville for a check out, update and new bulbs. Shipment to Norway was seamless with USPS.
The Kuehl Evaporator core is larger than the stock Behr unit and obstructed by a baffle plate in the suitcase. The Kuehl is a much nicer unit than the Behr in my opinion.
My A/C works great now.
To maximize the extra core a baffle has to be removed from the suitcase
Removed baffle piece
My flap doors had the rubber coming off so I rebuilt them after carefully cleaning the old stuff off with solvent. Below are before and after along with the tape brand I used.
04-01-2021, 05:08 PM
A/C Evaporator-'Suitcase' expert needed...
