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Pelican Technical Article:

Evaporator Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$5 to $1,400

Talent:

***

Tools:

Flathead screwdriver, 3mm Allen, T20 Torx

Applicable Models:

Porsche 993 Carrera (1995-98)
Porsche 993 Carrera 4 (1995-98)
Porsche 993 Carrera 4S (1996-98)
Porsche 993 Carrera S (1998)
Porsche 993 Targa (1996-98)
Porsche 993 Turbo (1996-97)

Parts Required:

Evaporator, O-rings

Hot Tip:

Always replace the O-rings

Performance Gain:

Working A/C

Complementary Modification:

Clean out all of the vents

Changing out the evaporator on the Porsche 964 and 993 is not that difficult of a job, once you have removed the HVAC "suitcase" from the front of the vehicle. However, getting the suitcase out and back in can be very time consuming. If this is the first time you are going to perform this job you should leave yourself about 20 hours to get it done. Bear in mind that you will not be able to use the car while performing the work. Play it safe and give yourself a full weekend to accomplish everything. Take your time and take lots of pictures.

Things are packed pretty tight in modern Porsches and that includes the 993. One of the important questions you will ask yourself when you start working on your Porsche is: how the heck do they expect me to get at that part without removing this part? The truth of the matter is that a lot of times you do need to move other parts, systems or components out of the way to change something and then re-install them. Lots of first time DIY'ers get frustrated working in really tight spaces or end up damaging something they are not working on just to "save the time" of having to remove other components. If you are going to work on your 993, get in the habit of moving things out of the way and give yourself all the room you can to work; in the end you will end up saving time and money.

Over the years Porsche has changed small things on the HVAC unit but procedure is the same. Just make sure to check that you have disconnected all of the wires and lines that you need to. Also, over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and hardware. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

The evaporator essentially works the same way as a condenser, except in reverse. The idea is that once the pressurized refrigerant has been condensed into a liquid, then depressurized and cooled by the expansion valve, it enters the evaporator, which due to its construction allows the temperature of the coils inside to drop considerably. Usually, then a fan blows air over the cold evaporator coils. The oncoming air is then cooled by the evaporator and sent out the vents of the dashboard.

You are going to be opening the A/C lines. It is very important that you have the refrigerant removed and stored or disposed of by a professional before you open the lines. Opening up charged A/C systems and venting the refrigerant to the atmosphere is illegal and dangerous, please make sure to have your refrigerant professionally removed and re-installed if good or properly disposed of!

I recommend that you fully remove the suitcase along with its wiring harness.
Figure 1

I recommend that you fully remove the suitcase along with its wiring harness. There are all kinds of short cuts on the internet for not removing the wiring, or changing the evaporator with the suitcase loose but in the trunk. This is one of those times that being thorough can end up saying time and money. Please see our article on how to safely and completely remove the suitcase from your Porsche and once it is out take it to your bench to work on.

The evaporator is housed inside the suitcase (red arrow) just below the expansion valve (yellow arrow).
Figure 2

The evaporator is housed inside the suitcase (red arrow) just below the expansion valve (yellow arrow). The lines in and out of the evaporator are connected to the expansion valve. You must "split" the case or separate the top section from the bottom to replace the evaporator.

Figure 3

Begin by removing all of the metal clips that help seal and hold the case together (red arrows)

Make sure to turn the case over as there are some hidden on the bottom and other places (red arrows).
Figure 4

Make sure to turn the case over as there are some hidden on the bottom and other places (red arrows).

Use a small flathead screwdriver and gently unclip them.
Figure 5

Use a small flathead screwdriver and gently unclip them. These clips can fly off at a great rate of speed so wear eye protection and better yet cover them with a rag while removing so they don't shoot across the room.

Next use a T20 Torx and spin the bird cage until you can see the two screws at the back and the openings in the cage line up.
Figure 6

Next use a T20 Torx and spin the bird cage until you can see the two screws at the back and the openings in the cage line up. Use your T20 Torx and remove the upper screw in each wheel (red arrow).

There is a single T20 Torx screw that needs to be removed in front of the center duct (red arrow).
Figure 7

There is a single T20 Torx screw that needs to be removed in front of the center duct (red arrow).

Now remove the single T20 Torx screw on the upper section by each blower motor (red arrow).
Figure 8

Now remove the single T20 Torx screw on the upper section by each blower motor (red arrow).

Finally there are two T20 Torx screws hidden in front of the expansion valve (red arrows), remove these as well.
Figure 9

Finally there are two T20 Torx screws hidden in front of the expansion valve (red arrows), remove these as well.

Use a 3mm Allen and remove the two bolts holding the expansion valve to the evaporator.
Figure 10

Use a 3mm Allen and remove the two bolts holding the expansion valve to the evaporator.

Pull the expansion valve off.
Figure 11

Pull the expansion valve off. There will be two O-rings on the lines from the evaporator that you will need to replace (red arrows).

Slide up the metal base plate that holds the evaporator lines into the house and remove the plate (red arrow).
Figure 12

Slide up the metal base plate that holds the evaporator lines into the house and remove the plate (red arrow).

You can now easily separate the housings.
Figure 13

You can now easily separate the housings. If the housings will not separate you have missed a clip or screw, so double check. When reinstalling you need to make sure that the rod for the flaps on the lower section (red arrow) goes back into the actuator on the top section.

Pull the temperature sensor out from the top of the housing and the evaporator (red arrow).
Figure 14

Pull the temperature sensor out from the top of the housing and the evaporator (red arrow).

The evaporator can now be easily lifted out from the housing.
Figure 15

The evaporator can now be easily lifted out from the housing. Clean, inspect, test and replace as needed.

Make sure to clean all of the old foam out from the housings (red arrow).
Figure 16

Make sure to clean all of the old foam out from the housings (red arrow).

The new evaporator will come with new foam that helps seal it to the housing and absorbs a little vibration.
Figure 17

The new evaporator will come with new foam that helps seal it to the housing and absorbs a little vibration. Use your old evaporator to see where to install the foam. Installation is the reverse of removal. I recommend you take the car to a professional A/C repair facility to have the system pressure tested and recharged, just do not run the system until it has been tested and charged.

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Page last updated: Sun 5/28/2017 03:20:41 AM