964 dies when heater blower is on

[Call4911]

I have a 1989 C4. When the heater blower is on, the engine stalls. The heater does not come on again after it has initially heated the passenger compartment. The engine just had a major service. It seems like the heater is draining power. Any ideas?

[S ECU Repair]

Sounds like a very weird problem...

Can you try disconnecting the Climate Control Unit (HVAC CCU this controls the rear aux heater blower) from the harness of the car then activate the Rear Aux Fan while the engine is idling by using a jumper on the Rear Aux Fan Relay in the Engine Bay Fuse box to see if this make the engine stall again?

This way you can separate a whether the HVAC CCU is affecting the engine or influencing the DME ECU.

[Call4911]

Originally Posted by S ECU Repair

Sounds like a very weird problem...

Can you try disconnecting the Climate Control Unit (HVAC CCU this controls the rear aux heater blower) from the harness of the car then activate the Rear Aux Fan while the engine is idling by using a jumper on the Rear Aux Fan Relay in the Engine Bay Fuse box to see if this make the engine stall again?

This way you can separate a whether the HVAC CCU is affecting the engine or influencing the DME ECU.

Thank you. I will pass this onto my Porsche tech. He is really knowledgable and he has never heard of this. It is weird.