tj90

Ok - we are almost to the evaporator - Crack open the airbox, swap evap, put everything together, and recharge. The airbox is the most complicated portion of the DIY. With that said, it looks intimidating, but actually not that bad. I strongly recommend digital camera so you can refer to the pics if you have a question during reassembly.

To give you some motivation, heres a pic of my A/C system after the DIY. Not bad for A/C sitting in the garage at idle. The coldest I got was ~ 5 C on the road. These temps, according to service manual, are within porsche spec.

tj90

First thing to do is disconnect the AC lines to the expansion valve. Its the 10 mm bolt. Now you can swing the 2 air conditioning lines out of the way. There is a retaining screw that must be removed to move the lines. I use the hood to hold the lines. The insulation protected the car finish.

You see the baggies on the lines? I attempted to close off the lines per good HVAC practices, I soon abandoned this method for balloons that worked much better.

Behind this bolt are 2 3 mm allen bolts. Remove those, now the expansion valve can come out. Pay particular attention to the O-rings. When reinstalling, you need to use new o-rings. Matching up the replacement o-rings is critical to prevent system leaks.

tj90

This step is easy, just start disconnecting the harness, vacuum lines and drain from the airbox. Below are close up pics of the plugs that must be disconnected. This stage seems like a free for all, but take your time and refer to these pics or your own for reassembly. I will not pretend to identify each component of the assembly, but Im sure they all have a name....

I apologize that the pics are out of sequence (I can hear it now - why is the expansion valve back on the airbox?) dont pay attention to this, my disassembly was not as smooth as yours is going to go by following this DIY....

tj90

There are 2 air ducts that feed the airbox on the left and right sides. They come up directly under the pollen filters. Each duct has 3 plastic snap connectors that must be depressed before the airbox can be removed.

If you are not careful, the plastic ducts can crack when removing the airbox. I believe the 993 is different than the 964 in this area. I believe that you can reuse the existing ducts if you are careful. The common thought is that the ducts must be replaced on the 964.

If you press down on the duct, it compresses a little in the trunk floor to give you more clearance. DO NOT press down on center bar on the inside of the duct - that piece can and will break - ask me how I know!

tj90

Now that the airbox is out, we need to take off some more topside components labelled in the picture.

Take your small flatblade and remove all the small retaining clips around the entire airbox. There must be 20 of them.

You will find 4-5 torx head screws that need to come out as well.

I forgot to mention that on the top of the airbox there are 2 temp sensors(?) toward the back of the airbox that must be removed with a T-10 torx screwdriver.

Finally, there are 2 hidden screws in each of the fans. These must be removed to separate the 2 halves. If you turn the fan, you will find that porsche keyed the fan hub to line up with the screw heads for removal.

tj90

The 2 halves of the airbox come apart easily. If they dont, you must of missed a screw or clip.

Wow, look at the nasty evaporator. I bet with all the gunk, it couldnt cool anything!

Because of the leak, oil from the AC system must have gone everywhere externally and my evaporator was like a K&N air filter!

tj90

I will cover reassembly tips as well as A/C recharge in part 4. I was originally going to do it in part 3 but I need to get some sleep.

maurice97C2S

I must renew today !! 2 DiYs at once .... excellent work, absolutely excellent !

cheers, Maurice

The Eagle

WOW, nice write up, nice pics.
Thanks for sharing!!!


__________________
~ The Eagle ~

'96 Polar Silver/Black C4S, manual, litronics, alu/leather shifter & handbrake, silver face gauges with alu rings, "GT" sport seats,
full leather interior, stainless door sills with split rear grill and layered with Meguiar's NXT Tech Wax
__________________
'92 Carrera 2 (Sold)
'89 Carrera 3.2 (Sold)

Ron

You might want to consider checking the brushes on the blower motors to see if they are almost worn out. If they are consider replacing the motors.

jnor10

~47 F : not too shabby. Sounds like it all went well. Thanks for all the documentation. Hope I don't ever need it, but nice to know there's a reference.

Speaking of which, did you have a manual or just winged it?

Jeff N.

tj90

I used the porsche PSM and alldatadiy.com. I have to say the PSM was not detailed enough - saying things like disconnect harness, remove airbox....

Alldatadiy.com is a great place to get the specs (that are in the PSM) on proper torques, pressures, capacities of the HVAC system.

Lastly, it was the 964 board post that helped as well. There used to be pics, but now they are gone and its just text. There was helpful posts on the 993 board as well.

And of course I winged it in a few areas - another rennlister may have a better way...

helmet993

I just tackled this job, didn't want to start another thread either so I figured I'd tack on to TJ's original.

All in all a 'fun' DIY. The absolute MOST DIFFICULT part for me was the bend required for the Kuehl evaporator. The instructions are clearly backward, the tip should point up not down as instructed if you read the instructions literally.

I took a lot of breaks mostly to ease the back from bending over and working hunched over and worked in total 12 hours including charging, cleaning the garage, petting the dog, talking to neighbors. The most rewarding part was having to turn up the temp on the a/c dial on the way home after the recharge, with ambient temps almost 90F on my 25 minute commute.

There are a lot of threads with bits and pieces of information, it'd be great if I would have had Moderator access so I could merge them all into one. But I wanted to help identify some of the more difficult areas of this DIY surrounding the airbox, specifically the footwell vents.

The first picture shows the airbox, already "out" with topside components removed. The two screws inside the fan motors are documented well. The picture details the torx heads you need to remove to separate the top and bottom half of the airbox. The arrows point to the two 10mm hex head bolts you must access through the fresh air intake grill before the airbox will come out of it's hole. Also I counted 23 (If I remember correctly) silver clips that you can see in the red plastic parts holder in the lower right. There are only 3 that are hard to find, on the back just under the vacuum capsule/bypass air flap contraption.



The picture below is a close up of the footwell vents the airbox connects to...they move very easily once popped out. As others have done previously I used a putty knife and really had to wedge it in to pop the two on the backside out and then used a trim stick or a dinner table knife to pop the front side one. The left and right interior kick panelss can be removed to pull these down from the inside, it only takes a moment and is very helpful. Do not worry about damaging the felt surrounding the vent plastic, it is pretty durable.

"Up" Position:


"Pushed down" position:


The airbox side of those footwell vents:


When you're done, put the radio in first so you can watch the wiring get caught up in the hooks from the CCU hole...use some painters tape to keep your dash nice and pretty (trick learned from Mark Wilson and Ginger)


A good helper is always nice to have:


And finally, hooked up to the a/c machine to make me cool again:


Please ask questions if you need anything clarified.

Paul M

I plan to tackle the evaporator replacement job on my car next week. After reading the diy, I do have a question - is it absolutety necessary to remove the compressor and drain the compressor oil?

I'm tempted to skip this step. It's one less set of joints to break and remake, and one less area to leak after buttoning up.

What is the benefit? Just knowing that the 15 year old compressor has clean, healthy oil?

helmet993

Paul, I did not drain the compressor, I just added the amount of oil for an evaporator/expansion valve replacement as noted in the shop manual...