2011 Chevrolet Volt Owner's Manual - Page 386

10-20 Vehicle Care What to Use The power electronics and charger modules coolant reservoir in the vehicle is filled with a 50/50 mixture of DEX-COOL engine coolant and deionized water. If using this mixture, nothing else needs to be added. Cooling System (Power Electronics and Charger Modules) The power electronics and charger modules are cooled using the same coolant loop. The power electronics and charger modules in the vehicle are kept below a maximum temperature. If the temperature rises above this temperature, the electric engine cooling fans will turn on and cool the coolant until the correct temperature is reached. Checking Coolant The vehicle must be on a level surface when checking the coolant level. The power electronics and charger modules coolant reservoir is located on the driver side of the engine compartment. See Engine Compartment Overview on page 10‑10 for more information on location. Check to see if coolant is visible in the power electronics and charger modules coolant reservoir. If coolant is visible but the coolant level is below the cold fill line, there could be a leak in the cooling system. The power electronics and charger modules coolant should only be serviced by a qualified technician.