1993 911 C2 Coupe

[Akelsch]

Having a problem where i am getting very hot air blowing through the front vents while driving.

AC does not work nor does defrost, defrost goes on for 1 second then dies down to nothing, tried putting free on in the AC system with no help.

Anybody have any ideas, other then that engine running fine

Also spoiler staying up for some reason.

[TMc993]

Look here Porsche 964 / 993 CCU electrical repair for diagnostics on HVAC.

[RedCoupe]

Another thing to look for are the flapper valves that are in the rear wheel arch on each side. The earlier cars (3.2 and earlier) had cable operated valves that either sent hot air forward to the cabin or dumped it underneath the car, depending on the setting of the control levers. The 964 has valves that simply respond to changes in pressure: they don't have any cables that attach to them. When the control unit calls for heat it opens a valve up front and the pressure in the hot air hose drops. The valves in the rear wheel arches are then supposed to open and send hot air forward. Unfortunately, when the flapper valves stick they can send hot air to the cabin all the time. This hot air can leak past every seam and seal in the system so pretty soon everything and everybody inside the 964 is boiling hot!

[Akelsch]

Is this something that is a complicated fix or simple.

[TMc993]

Originally Posted by Akelsch

Is this something that is a complicated fix or simple.

It depends...If you are fairly confident with tools, it's not really bad. But if you never work on your car, you may want to take it to a shop. At a minimum, I would look at what RedCoupe said and if that's not the culprit, read through Tore's diagnostics. At least you'd have an idea of what is going on before turning it over to a shop....Hope it works out for you.

[Akelsch]

Are those flapper valves to open or close accessible ? and what to look for ?

[Akelsch]

also the hot air is blowing out of the vents not just the cabin getting hot,

[crg53]

One way to check if your flapper valves are working is to close the door with a bit of force, like a slam, and you should hear a metallic sound like something is loose and "flapping" around.
HERE is a link to what the flapper valve looks like, its located in the forward side of the rear wheel well.

[Akelsch]

Originally Posted by RedCoupe

Another thing to look for are the flapper valves that are in the rear wheel arch on each side. The earlier cars (3.2 and earlier) had cable operated valves that either sent hot air forward to the cabin or dumped it underneath the car, depending on the setting of the control levers. The 964 has valves that simply respond to changes in pressure: they don't have any cables that attach to them. When the control unit calls for heat it opens a valve up front and the pressure in the hot air hose drops. The valves in the rear wheel arches are then supposed to open and send hot air forward. Unfortunately, when the flapper valves stick they can send hot air to the cabin all the time. This hot air can leak past every seam and seal in the system so pretty soon everything and everybody inside the 964 is boiling hot!

How do I find the Flapper Valve to close it ?

[RedCoupe]

There's no manual closed/open control on the flapper valves. You just need to make sure that both of them (one on each side) move freely. Like crg53 said, when you shut the car doors with the windows closed, you should hear that distinctive "clinking" sound on both sides. I think the sudden burst of air pressure in the car as well as the shake, makes them do that, but if you don't hear that noise, you have a problem.

[Akelsch]

Originally Posted by RedCoupe

There's no manual closed/open control on the flapper valves. You just need to make sure that both of them (one on each side) move freely. Like crg53 said, when you shut the car doors with the windows closed, you should hear that distinctive "clinking" sound on both sides. I think the sudden burst of air pressure in the car as well as the shake, makes them do that, but if you don't hear that noise, you have a problem.

I did that heard what sounds like a peanut can rolling twice. Is that good or bad.

[RedCoupe]

If you hear that sound, it means that at least one of the flapper valves is working. I would check that both are working by looking underneath and moving the flap, but I suspect that your trouble is likely to be with the control unit itself or the control solenoids. Go to the link that TMc993 provided to guide you for the diagnosis.