My 1980 450SL exhibited the same symptom a number of years ago. On mine it was caused by a vacuum leak in the HVAC system. An actuator that controlled an air flap had begun leaking. Blower would stop when I'd accelerate but restart when driving normally.

I found it by isolating each actuator and pulling a vacuum on each separately. This can be done by attaching hoses and providing the vacuum yourself. But mine is a 1980....

__________________
Lawrence Coppari

2002 SLK32 AMG
2005 Acura TL
1987 328GTS
1986 944T