jac911

A recent thread talked about servicing these fresh air servo motors. I found the three behind the gas tank no problem. There are supposed to be servo motors in the drivers and passenger foot wells. I checked the drivers footwell but there was no motor visible. I believe I read somewhere that the foot well servo's were deleted on the 98's but I could be wrong. Haven't checked the passenger foot well yet. It's on my agenda. Should there be one on the driver's side?

Also, it was suggested that those motors be serviced. Looking into the trunk behind the gas tank, I checked the action of the motors on the left and right. They do function correctly when activated. From the readings I've done, the center one only actuates when the car is moving but never closes completely. My question is.....since the motors seem to be functioning, should they be left alone or should they be taken apart and cleaned and lubed. My thought is....if it ain't broke, don't fix it but if servicing them will prevent breakage, then I'll do it.

What's the consensus on servicing these motors. Any help much appreciated.

JC
98 C2S widebody

bjornebo

Re the servo motor in the driver's footwell, there is a cylindrical metal piece connected to two hoses (one hose brings hot air from the engine bay and the other goes to the climate control assembly). This metal piece contains the flap that determines how much hot air goes to the heater. The motor is attached to this metal piece. This is shown in Figure 813-00 in the 993 PET. This is what I have in my '97. I haven't heard that they eliminated this for '98, but I doubt that they would have done so because without the flap and motor there would be no way to control how much hot air goes to the heater.

ToreB

There is no need for servicing these servos unless they have failed. Do NOT lubricate the servo internals. The gear box needs some plastic gear grease, but with very careful application to the final gears to avoid problems. Unless contaminated, the original grease is quite sufficient.
You are indeed wrong, all 993's has the same servo setup, there were no changes in 98 models. The fresh air servo shall close at ignition off, and move continiously while the car is used in order to control the cabin temperature. This is also the case with the two mixer servos in the foot wells. Movement depends on the CCU temp setting and ambient temperature.
See this page for a DIY test procedure and fault overview.
Cheers,
Tore

pp000830

Answers:

1. Did you remove the carpeted side wall cover? It is easy to remove, held in by screws;
2. The motors can't really be serviced, they can be rebuilt from kits or sent out to be rebuilt by Partisan Parts
3. It is not possible to fully evaluate them simply because they are moving, if you are experiencing HVAC issues it is best to run the OBDC codes with Durametric or other readers that can read HVAC codes.
4. They are not serviced unless you have functional issues with your HVAC, the fresh air servo seems to be the first one to go, the one on top-center in the frunk.

Here is good diagnostic information on the HVAC system:BergvillFX Web Site. I have rebuilt one out of my car and found it to be a relatively easy kitchen table DIY. The instructions that come with the kit from Partisan are good,

The only things I would add to them:

• Use wooden toothpicks as wedges for each of the individual case latches around the periphery of the case when opening the case. By doing this all the catches can be released at the same time so the case halves can be separated without putting undue force on the overall housing. Also;
• On my fresh air servo, there was a screw I was unable to remove holding the plastic actuator arm on the shaft. I ended up carefully drilling the head of the screw off, using care to, go slowly and not melt any plastic, to slip the arm off. When replacing the arm the friction fit of it on the shaft has proven to be enough to hold the arm in place now for several years so the screw seems to be unnecessary.
• When removing the fresh air servo turning the ignition on after detaching the metal plunger shaft from the plastic actuating arm in most cases will cause the actuating arm to move 90 degrees into position so it clears its mounting frame and can just be lifted out without further disassembly of stuff around it. The kit comes with a replacement clip to hold the plunger to the actuating arm so if you lose the old one no biggie.

Andy