I now have Carsoft 7.4 and have been testing it on a 97 E320 and 97 SL320.

When testing the E320 I felt heat coming from the heater valve area ( Motor was cold, it has not run in a year due to bad fuel pump.). The heater valve solenoids were in the first degree burn range. Not something I would expect since the HVAC system was not on during testing.

Today when testing the SL320, the same thing occurred under the same conditions. I usually don't leave the ignition key on for 20 minutes so I can't be sure this would occur without Carsoft being attached.

Has anyone had this occur?

I guess the next question would be, is the heater valve open when power is applied or closed?

I suspect closed as most ( all? ) heater systems I've seen default to heat / defrost if they loose power / vacuum. This might even be a USA federal requirement.

Thanks