[W126 Coupe] Air Conditioning Diagnosis

[Dick Spellman]

Dan Landiss wrote:

> Switching from the maximum cooling position (up and down arrows on the 

> button are both white) to the next position (is it white for the down 

> arrow only?) definitely changes the air flow. The former results in a 

> LOT of air on the windscreen, and the latter almost none.

Run all AC tests using the middle button only.  Cool air to dash vents 
and floor with a minimal amount to windscreen.  You are correct the 
WHITE UP WHITE DOWN throws a volume of air to the defrost vents and 
windscreen.  This is okay when you are getting outside air condensates 
on the windscreen (fogging) and you should switch back to the middle 
button (BLACK UP/ WHITE DOWN) when the windscreen clears.

Also, running in RECIRC mode (presuming you have this separate switch) 
is fine and automatic shift to 20% makeup air occurs at 30 minutes when 
temps are above 7C (approx 50F) and 5 minutes below 7C.

Dick