The most common reasons a Volvo V50 heater isn't working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor. 0 % 31 % of the time it's the Heater Blower Motor 0 % 24 % of the time it's the Thermostat 0 % 18 % of the time it's the Heater Blower Motor Resistor 0 % 27 % of the time it's The MCC, manual climate control will have a fan speed switch with 4 speeds and the temperature control ***** go cool to hot. The ECC, electronic climate control will have a slider for infinite fan speeds and the temperature control ***** will have numbered temperature selection. Attached Thumbnails. When I reconnected the controller to the four prong plug under the dash and check the output to the fan at the two prong connector I get a steady 12 V regardless of whether the fan switch is on or not, and even if the key isn't even in the ignition. If I then plug the fan back into the controller it doesn't spin and I get 0 V at the fan terminals. DYE85.

volvo v50 heater not working