Overview. The original cold air flap actuator diaphragm cracks with age and leaks vacuum. This 40mm silicone diaphragm restores the actuator without replacing the housing.
Fitment
- W124 cold air flap actuator (124 800 03 75 / 124 800 01 75)
- BMW and Behr actuators using BMW 1363136.2 / Behr 90618130115
Cross-reference part numbers (this diaphragm rebuilds these actuators):
- W124 cold air flap: Mercedes-Benz A 124 800 03 75, A1248000375, 1248000375, 124 800 03 75, 124 800 0375, 124-800-03-75, 124.800.03.75
- W124 cold air flap: Mercedes-Benz A 124 800 01 75, A1248000175, 1248000175, 124 800 01 75, 124 800 0175, 124-800-01-75, 124.800.01.75
- BMW 1363136.2, 13631362
- Behr 90618130115
What’s included
- One 40mm red silicone single-stage diaphragm
Installation
Rebuild tips
- Old actuator plastic can be brittle: open housings with 4 thin plastic strips (an old credit card works)
- Clean dust and debris from the housing; don’t use lubricants
- Stretch the diaphragm rim by hand just before closing the housing
- Test with a hand vacuum pump (e.g. Mityvac)
Good to know
- Also included in our W124 Vacuum Actuator Rebuild Kit




