rbeggs

Does anybody know the whereabouts of a block schematic of the 993 HVAC
systems? Air flow map and components. Nothing's as good as a visual flow chart to nail down the concept behind the system. I've scrounged around the list but haven't found anything. I'm trying to make my own based on info from Streathers fine book but have run into some inconsistencys I can't resolve. I've got to see it before I can understand it. Ideally it would detail the subtle change between '95-'96. If none exists I'll plod on and if succesful, pass it on.

JasonAndreas

I've posted them for the 964 but unfortunately I don't have the exact same material for the 993 BUT its not really that different.

What have you run into that doesn't look right?

The only difference (I can think of) is the fresh-air intake in the engine compartment, above and to the left of the engine? If you can find the Service Technik for 1996 it should describe the changes.

rbeggs

Jason,

Thanks for your reply.

What is not clear to me is the difference in the recirculation mode between '94-'95 (not '95-'96). Where does it physically join before the left and right blower?

Next. If the heated air from the engine bay is pulled into the system by the left and right blowers as is fresh air, how can the mixing chambers be downstream? Where does the hot air join the stream? This is what I stumble on in Streathers explanation. I'm missing something.

Is the "blower fans final stage amplifier" two (left/right) units or a summed chamber that outputs into the cabin interior with a blower?

I'm probably making this more complicated than it is. Hard to imagine though.

Another question. Do the centigrade indications on the heater **** really bear any relationship to actual temperatures? What is a reasonable tolerance? My measurements show about a 12 degree centigrade offset between indicated and actual at the CCU air inlet.

Thanks.

Lorenfb

"I'm probably making this more complicated than it is."

Right. So what's the BASIC problem?

rbeggs

Aside from the fact that the air conditioner seems to not work quite right, too cold right now to really tell, there is no "basic" problem. I just want a map of the system to help my understanding of what's going on.

When and if there's a "problem" I'll be more confidant in dealing with it if I have the visual. I suppose for now it's idle curiosity. My 356's heating is basically a pipe with a hand adjustable lid. This (the 993) is another order of magnitude.

Thanks,