The expansion valve on a 126 is one of the most difficult to replace...It is located under the dash behind and above the accelerator pedal. If you are not very careful, you can damage the evaperator when changing the valve because it is directly connected to it.
If you are replacing so many other things, be sure to get new swithces for the drier. they usually fail soon after a repair.
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM