Mercedes A/C Problem



My 2002 E320 has an intermittent A/C problem that relates to engine RPM/torque requirements. At idle or when cruising under low torque conditions, the A/C works fine. However when accelerating or going up hills, the blower fan stops working.


Are you sure the fan stops working? Could it be that the vents close?


It’s more likely that the vents are changing position, and the recirc door may be closing too. This would indicate a vacuum leak somewhere in the engine or the HVAC system, or a faulty check valve between the engine and the HVAC, in the vacuum line.



Yes you are right, the vents change their position as well. The Blower’s RPM’s may drop because of the vent closure. Still don’t know why! Thanks


Hey Thanks Matt, I will look in to it.


Something to keep in mind is that on most cars, the A/C compressor will disengage while there is a high power demand on the engine (accelerating, going uphill). I suppose that the whole system could turn off to avoid blowing hot air on the passengers, but your posting seems to indicate that this is a recent problem. As others have suggested, the first place to look is for a vacuum leak that is causing various doors to shut.


Try these guys, there are a few folks here who really know these systems: