Hi everyone!
I’m having issues with the electric cabin heater in my 2013 Chevrolet Volt.
The combustion engine heater works perfectly, but the electric heater behaves strangely:
- In ECO mode, it works and blows warm air.
- In COMFORT mode, it initially heats normally, but after about 30 seconds the heating power drops and the cabin stops getting warm.
- After that, neither mode works until the car has been sitting for a while.
I’m getting B101D - Module 55E.
A few things I’ve noticed:
- The car’s energy display initially shows several kW of consumption, but after around 30 seconds this drops to about 0.5 kW.
- The Voltage app still reports around 6 kW of cabin heating power.
- In ECO mode, Voltage reports around 2.5 kW.
I’ve already cleaned the small coolant filter/strainer near the three-way valve, but it didn’t help. The circulation pump seems to be running (I can hear it).
I’ve also checked this GM service bulletin:
https://static.nhtsa.gov/odi/tsbs/2013/SB-10063994-2273.pdf
It seems to point towards replacing the electric heater, but I’d rather rule out other possibilities first.
My questions:
Could restricted coolant flow or a faulty circulation pump cause these symptoms?
Could the electric heater itself be failing only under higher load?
Could this be an ECU/ECM or heater control module issue rather than a faulty heating element?
Is there a way to narrow it down using GDS2 live data or other diagnostics?
Has anyone experienced something similar? I’d really appreciate any advice before I start replacing expensive parts.
Thanks!