HVAC Overhaul - ZA 745i

[finnyracer]

Been a while since I've been on the forum.

I have finally taken the plunge to sort the HVAC system on my 745i. I checked all the vacuum lines from the pump going back to the vacuum reservoir, and all seemed to be in order, except for the one-way valve going towards the engine.

The heater had been bypassed and I don't know whether the heater was staying on or whether the heater core was leaking, so removing the air box was necessary.





Now that the air box is out and on my workbench, I've had a bit of time getting my head around it and understanding which pod opens what, but I have some questions:

1) The pink pod that activates the flap for the centre and side vents holds vacuum when I test it where the orange hose enters but doesn't hold vacuum at the yellow hose - I assume one of the diaphragms is leaking?

2) Why would it be a double pod and what does a double pod do compared to a single pod?



3) The green pod holds vacuum at the blue pipe, but not at the white one - also a split diaphragm?



4) Do the solenoids ever give trouble or are they reliable? How can I test them?
5) Where can I buy replacement diaphragms?
6) Does anyone have the part number for the grey and black one-way valves?

[BONDOSPECIAL]

George Murphy @ perfanalysis sometimes has replacement pod diaphragms in stock, you might want to check with him (you would use these to rebuild your existing pods)

inquiry@perfanalysis.com

865-482-9175

[finnyracer]

Thank you, Steve - I have been in touch with him.

[Hit Man X]

I have only had good luck with the single pod rebuild kits from George. But for $7USD you cannot beat it. The duals just use off a W126 Mercedes. W123/124 should work too. Yes, you can even use the MB spec plastic connector. The rear seat airflow one is from a W124, it is about the size of a golf ball. If they have gone NLA, just pop the flap open and leave it that way. The airflow is pathetic anyway, I would be surprised if could blow out a birthday candle.

I usually ditch the LF dual tit cowl pod. I safety wire shut the flap. The RF opens plenty for 'fresh air' as needed. Simply less crap to move, less crap to break.

Replace heater core while in there, guys in East Europe have one for about $75USD. I have one here, seems like a nice piece. If you can, locate a 09/85+ evaporator core. It has quite a bit more surface area to remove cabin heat. Do the late condenser too as well as a late crank pulley. Tons of small things can help with A/C performance.



The photos did not show up on my end.