Fat993

Now that winter's arrived, I noticed my '95 993 gets exhaust fumes in the cabin upon engine startup ..... but only when the ac/heater thermostat is above full cold and even when the fan control is on zero. This happens only at startup and I don't notice exhaust fumes while driving or while idling at a stop after driving. Had Fabspeed sportcats/muffler/airbox kit installed this past summer. This winter is the first time I noticed the exhaust smell at startup with the heater on. Any ideas how to stop this?

Linnm

If you are really getting exhaust fumes in your 993 you had better have it flat-bedded to the nearest dealer for a checkup. Exhaust fumes mean carbon monoxide which is deadly..

I have been driving my 993 for a little over 15 years and have NEVER experienced a smell from the heater/AC system

ToreB

Any settings above lowest temperature opens the two mixing flaps to let heated air from the engine to the cabin. The auxillary fan in the engine bay push air from behind there, and goes up to high speed at fan setting 2 or 3. Cold air only is either via the resirc opening in the cabin or the fresh air intake under the windscreen.
Obviously there's a leak from the exhaust to the air heater boxes. As mentioned above, get this sorted, it's deadly.
Cheers,
Tore

IXLR8

You mean a "real" Beetle?

Yup, was going through the gears on one in a parking lot when I was 8.

I started early.

IXLR8

No but it could have a faint smell of oil if oil has seeped into them due to leaking valve covers.

The insides of my heat exchangers were oily and dirty. When I had them off to replace all exhaust gaskets, valve cover seals and spark plugs, I flushed them clean with a water based degreaser.

The only way you could smell exhaust fumes is if you had a crack in the exhaust manifold within the exchanger jackets.

slickster85

This is what is happening to me as well, figure its just the cracked pipe? What else could it be?

Fat993

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Thanks ToreB and Linnm! Yes, it's actually exhaust smell, which I had not had previously (I'm original owner). I'll be taking my 993 to the shop. I had a Fabspeed sportcat and muffler system placed during the summer. Recently had the flywheel/clutch changed out, which required the exhaust system to be taken out and put back in. Would that potentially have any effect on the ability for exhaust to get in the cabin when the thermostat is set higher than full cold?

FredSmith

Hi all, on the subject of heating, could someone help me with my question please? My 993 heater control unit works in hot & cold mode, the fan also works in both, but... if the heater is turned up on the dial the fan will refuse to go any faster than the number 1 speed even if I turn it up to number 4 speed. In cold mode its no problem. So, I took out the heater control unit from the dash to look for a possible cause. Other than maybe an electronic fault in the heater unit I noticed (as you can see in the photo) a valve / actuator and a round end spindle. It looks like the lever from the valve should sit on the spindle, I've tried to fit but, if it is meant to fit it is very difficult to get it over the rounded end. I hope all that makes sense?
Could anybody shed any light or thoughts on this please? My 993 is a 95 Cab model, non Varioram & no AC. The picture below is what you see behind the dash control unit.
Many Thanks....

FredSmith

To add further, the spindle from the valve will move in / out with hand pressure but the rounded peg that you see is static.

ToreB

What you see is the recurculation flap. I guess you have a an early 1995 model, maybe with the round 19-pin OBD port in the passenger foot well?
The first 993 models have a spring loaded recirculation flap, just as the 964. There was a gradual transfer to the 1995/2 model with the vacuum operated recirc flap. Some early models have the vacuum actuator, but not the connecting rod or the vacuum hose and valve.
The early 993 model is easily determined by the part number of the Climate Control Unit, if it has a part 993 part number ending with 00. (993 659 04x 00) or a 964 part number, (964 659 04x 01) you have early 993 model.
CCU's with part number 993 659 04x 01 has provisions for the later 993 features such as the recirc flap.

When heated air is needed to the cabin, the rear fan in the engine compartment shall start to help pushing hot air forward to the cabin.
This fan is supposed to run in two speeds, depending on the Climate Control Unit speed **** setting. Low speed is obtained by a resistor in series with the fan motor. The rear fan is supervised by the CCU, and if it does not work on both speeds, the CCU will shut down the main blowers to avoid drawing any exhaust gases into the cabin. Most often the inbuilt thermofuse in the resistor fails, and prevents fan on low speed, but it could also be a failing rear fan motor or its relay. See here for a DIY test procedure:
https://www.bergvillfx.com/categorie...test-procedure

Cheers,
Tore

FredSmith

Great! Thanks for the speedy reply Tore. I'll run the test procedure and see what happens. Any idea with regard to the photo? Do i need to loop the spindle over the peg? If so, that does seem very tricky :-(
Thanks again ! :-)

ToreB

I have already tried to help you with the recirculation flap. Major parts of the mechanism are not present in your car, and it might be that there shall be no such parts in your car.
Cheers,
Tore

Here is a picture of a later 993 model with all recirc flap parts present: Please ignore the red arrows.

FredSmith

Thats's great and makes sense... Thanks a million Tore, it really is appreciated.
Regards

JSF

That ball joint needs to be connected to the arm in the vacuum valve. Folks here have recommended using a Chicago screw if the original part has been misplaced. I found easier luck with a zip tie.

ToreB

This is not accurate, as several parts are missing in the picture. It applies to 1995/2 and later 993 models only, not for the 1994 and 1995/1 models. I highly suspect the latter is the case here. If one sources the missing parts and you do what you describe in an early models, you will stop any possibility for recirculation of cabin air, which will severly impact the HVAC operation.
All the best,
Tore