993 Evaporator Replace Experience

[Funracer]

Decided to replace the AC evaporator on my 1995 993. Taking the wife to Porsche Parade in Oklahoma City this coming July. Must have AC. I accomplished this over a couple of warm-ish weekends in mid January.

There are two excellent articles to guide the DIY folks through this involved project.
One on p-car.com and the other (broken into two articles) here in the Pelican DIY section. Both were written around 20 years ago.

My intent is not to rewrite either of these fine guides, but to add to them with better pictures where necessary and suggestions from my own experience.

Lots has been written about the labor involved in removing and replacing the 993 evaporator. Most estimates are 10-15 hours total. I found these estimates quite optimistic for a first timer. Maybe possible if you’ve done parts of this before and nothing goes wrong. I am old (67) and retired so no deadlines. First morning took the car to my local auto AC shop to get the R134 removed. Then elevated the front end, disconnected the fuel pump and drained the tank. Next day pull the stereo and AC controls, pull the firewall and remove the wire harness and finally lift out the “suitcase” containing the evaporator. Next day a couple of hours to open the suitcase, replace the evap and expansion valve, clean and put the suitcase back together. Another day to replace the suitcase and firewall, wire harness and interior dash components, and lastly another day to reinstall the gas tank and fuel pump. My point is, if you have never done any of this, leave yourself a couple of weekends at least to get it done.

The following are some of the problems I encountered.

To begin you will need to remove fuel from the fuel tank. My thought was to siphon as much fuel as possible and then drain the rest. I spent the next 90 minutes trying to siphon with a vacuum pump and also a hand pump. I was never able to maintain a siphon for more than a few seconds. Finally gave up and drained 4 gallons out the fuel pump line underneath. Disconnecting the FP was easy and straightforward.

Disconnecting the fuel fill hoses was harder than I thought it would be. Did not want to pry or twist them too hard because the fitting they are attached to are plastic. Gentle twisting with pliers finally broke them loose.

Once the fill hoses are free and the metal tank strap bolt is removed the tank can be lifted out. Roll it forward and wiggle side to side until it comes out from under the fuse panel tray on the firewall. You can get the fuse panel shelf out of the way by removing the firewall before lifting out the tank, but the bolts and screws are hard to get to with the fuel tank in the way. Much easier to remove the firewall after the tank is out of the way.

Removing the firewall is well documented in a separate DIY on Pelican. It outlines doing so with the fuel tank in place, but is much easier here as the tank will be out of the way.
There is a heavy heat sink on the back side of the firewall. The p-car article has you remove the two screws holding it to the firewall and separate it. I found it easier to leave it in place and just unclip the connector on top. As in the Pelican guide, the heat sink will come out with the firewall.

[Funracer]

Now that the tank and firewall are out next is evap suitcase. First remove the stereo head unit and AC control from the dash in order to access two nuts and one bolt on the back side of the suitcase. Read many places what a pita this was and was not looking forward to it. One of the good decisions I made before starting was to buy these:

I had never removed either and had them both unlocked from the dash in 5 minutes. Total. Super easy with these tools and for $14 a no brainer. Removing the plugs behind the AC control was a challenge so I ended up cutting a couple of zip ties under the drivers side dash to loosen the wire bundle and allow me to pull the control head out far enough to unlatch the plugs. There is one 10mm steel nut and one 10mm bolt on the ceiling inside the AC dash cavity, and one steel nut inside the stereo cavity that anchor the rear of the suitcase to the frame of the car. I say steel nuts because there are some 10mm nylon ones in there too but you are looking for the steel nuts.
Arrow shows the correct nut stud, not where my socket is in this pic. AC side is similar.


Next to remove is the left and right ducts that plug into the bottom corner below each fan on the suitcase. They pass up from each footwell and are locked into the suitcase with plastic tabs that snap into holes in the fan shroud. Three per side. The forward one is visible from the front, the rear two are not visible. I took several pics and marked them. From the footwell:

From the suitcase side after the ducting has been pulled out the bottom. Notice the single tab hole on the front and two on the back:

As the p-car guide says, do not push on the duct crossbar to help push it out. The crossbar is plastic and will break. Ask me how I know.

[Funracer]

Time to remove the suitcase? Not yet. Next just go ahead and undo the drain pipes under the suitcase. Not sure you need to remove them but I ultimately removed them to give me every millimeter space to get the suitcase out as you will see later. Cut the white tube zip ties and unscrew the locking tabs from the white corner drains to remove all the white drain pieces. Leave the black drains that pass through the floor and their zip ties in place. The black drains are squishy and will not hinder the suitcase when the time comes to pull it out. They are also a pain to reinstall.
Note the O rings inside the white tubing. Don’t lose them. Sorry these two pics are in reverse order.


Time to remove suitcase? Not yet. Now start unclipping all the wire loom connectors on top of the suitcase. It looks complicated but really is easy once you get going. The idea here is to separate the wire loom from the suitcase entirely such that it stays in the car after the suitcase is removed. I took several pics of the wire routing but didn’t need them as each connector only goes to one place when it comes time to reassemble. In the top center pull out the evap temp sensor (it just pulls straight up and out of the rubber collar). There are also a couple of vacuum lines to undo.
There is also a sensor at the top and behind each fan. They twist to unlock:

Remove the AC lines to the expansion valve if you have not already. Tape or cover the open pipes. I used a bungee to lift them up and out of the way. See next pic down.
Now, finally, the suitcase should lift out. Only mine would not budge. Noticed there are a set of ducts on top of the suitcase as well. At this point about ready to get mad a little. Hard to reach and the right one is locked in somehow. Hole and tab like the footwell ducts. Finall used a yardstick to reach in that slim space and push on the duct hard enough to unlock it. Geez what else!

Pic of the upper duct locking tab:

[Funracer]

Is it time yet? Remember you are reading the Pelican and/or p-car guides for all the steps and using this as just a supplement. They would tell you about such things as removing the fresh air grill to get at two bolts that will release the bellows. If you have read their guides this far and are still here……its time.

You cannot lift it straight up. You cannot pull it straight towards you. Kind of have to roll it out from the top. Only mine would not come out. It was quite loose. I tried for 30 minutes, reread all the steps, checked to see if I had missed a nut or clip or connectors or duct. It was at this point I went back and removed the white drain tubes because it couldn’t hurt. Even put a lever underneath the suitcase and tried to lift it up and out. Finally after a pull-forward-roll-from-the-top-while-lifting-move-it released to here:

I did eventually determine why it was so hard to remove but will save that for later.

Wire loom is secured on back with a zip tie in the left corner.

I have read some folks leave the wire loom in place and change the evap right there in the frunk. I could not imagine doing that but, as I said, I have as much time as I need.
I have to say, it looks good on that workbench!


Opening the suitcase and swapping the evap is actually not difficult and is well covered in both the aforementioned guides. Lots of clips and a handful of screws and cleaning things out once you get inside. The new one drops right in. I do have a couple of insights though.
I had read you could see the back side of the evaporator from inside the dash once the AC controls were removed. Once I had the suitcase on the workbench I saw just how easy this would have been. Mighty-Vac to the servo and she popped right open:



From here You can see the dirty backside of the evap, not visible from the cabin filter openings. This may have shown me that…….my evaporator actually was not leaking! Probably. Maybe. Red in the corner but the old evap held vacuum and light pressure (I put my thumb over one tube and blew on the other).


I think the more likely culprit was the expansion valve O rings:



Had to drill out the upper EV hex cap screw. That dark brown crust on the foam is suspicious. Just new O rings might have stopped the leak. Not sure if you can make it out but there is a good size sharp burr on the lip at the 11 O’clock position of the larger orifice.
But hey, now I have a new evap, so all good

[Funracer]

Once the new evap and expansion valve are in, putting it all back together really was straightforward, with a couple of minor and one medium size exceptions.

I figured the suitcase would just drop right into its cradle. I mean it was a pain to get out but surely it would reseat itself easily. It would not. I fiddled with the bellows on top, the upper ducts, wire loom etc etc and it just would not slide back into its cave. Pulled it out and put it back 4 times. Rolled it in from the top, lifted and rolled, wiggled side to side. Not having it. Something was keeping it a half inch from away from the back wall.
Here it is:

The footwell vac servo has to be on the other side of the lip with the red mark. No matter what I tried I could not get it up and over that lip because there is almost no vertical wiggle room deep in the suitcase cavity. Force might bend the servo bracket or worse yet break the nipple off. Finally called my helper (wife). With her using a 4 foot piece of PVC pipe as a lever to lift from the front and me inside pulling and lifting the servo finally came up and over and she was in!

This servo getting caught on the lip was also the reason I had a hard time removing the suitcase earlier.

Upper ducts required some persuasion to get them locked again. Footwell ducts popped right in easily. Wiring harness snapped into place. Then the firewall as per the Pelican DIY in reverse. Fuel tank dropped in easy. Reattached the fill hoses. Luckily I was looking through my pics and saw this one before I hooked up the fuel pump and added gasoline to the tank:

I had reassembled the drain system but forgotten to zip tie them as they were in this earlier picture. Visions of AC condensation draining into my frunk lead me to unhook the fill tubes, much easier this time, pull the tank and firewall, add zip ties and put it all back in again.

Reattaching the fuel pump lines was much easier than I thought it would be. Plenty of room to move things around and get things where they need to be. Added two gallons of fuel. She started on the second crank.

Over all I found this project to be exhausting and somewhat involved just because I had to learn each step as I went. Breaking it down into 5-6 smaller projects over several days made the overall thing manageable. I learned a ton about the front end of a 993 though and am pretty sure I could do this next time in, oh, 10-12 hours

[Funracer]

Just realized I never took a pic of the brand new evaporator! Too late now. This is the best I have:


Clean and shiny. System held vacuum for over hour too so maybe I did it right.