@drmitch

did you do the work yourself? is it difficult job? require any special tools?

i would like to go over the system up front. opened up the cover to the front and don't see the flapper boxes etc.

i am getting exhaust in my cabin when turning on the windshield demister and also getting heat in the middle and passenger side vent but not the driver side vent

i will close off the two oval 'intakes' in the header and see if that helps.

looks like the system works on differential pressure etc..

 

The flapper boxes are in the engine bay. I did the work myself, no special tools, have to remove rear wheel to access is all. PM me and perhaps we can meet up sometime. In the meantime, I'll see if I have any pics of what I did.

 

realizing this thread started in 2005!!

I pulled my driver's side heater flapper box and soaked in solvents and cleaners and still stiff as hell.

Are they scrap? Any way to get them to flap again?

I can open and close but needs a fair bit of effort

 

Drill out the "blind rivet" points and split the case. Clean it all up, including the plastic pivot points, lube and re assemble . I joined the halves with stainless bolts and nuts by drilling right through the joins where the "riveted" areas were.

 

@tdiquattro i'll try that fix as my flapper boxes will not release properly. no 'tink' per dr mitch. will be a winter project

 

Hoping to revive, as this thread seems closest to my issues, and maybe @JasonAndreas is still paying attention . 😉

Recently refreshed a number of dead or dying AC components in anticipation of warmer weather. I had failing HVAC blower motors, CCU fan, mixing servos, and oil and HVAC cooler fans. Finished all that work, but now have faint, but hot air from the driver’s side vent, even on full cold AC.

I have checked carefully to ensure front left mixing servo arm is properly clocked. At full cold setting, the flap is fully closed. You can see and feel as much.

Today I took the heater flapper box off and inspected. It’s in perfect condition. Almost zero resistance on the flap axle / assembly. Moves effortlessly. I can hear it rattle when driver’s side door is closed.

So what does this point to? Is there something else between the heater flapper box and the mixing chamber flaps ?

 

Can you use the Bosch equivalent UDT 999 to test these flaps by just the ignition being on and not fully running ? It's really difficult to listen for these little sounds and movements while everything is beeping and etc Or does the system have to be fully active ( ie heater blower going and etc) Thank you for insight.

 

The flapper boxes up behind the engine are not electronic, they're just hinged metal flaps that operate based on air pressure. The servos in the HVAC suitcase in the frunk are easier to diagnose, you can either 1) have a friend operate the CCU controls while you look at the servos (remove the plastic trim panel at the top of the frunk) or 2) move the CCU controls yourself and see if the system does what it's supposed to do.

 

This is on the list now to investigate Possible preventative ? ..... I used to hear the cling when closing the door, however recently my recirculation is never active - going to go listen for it and see all the mysteries that this HVAC is hiding with the scanner. Had recently focused on the blower fan relay blower ntc sensor and blower resistor. Now will expand .... Just have to find the time to hide in the garage ; good thing it's still winter here, for now time is still on my side. Thank you !!!!