Q: Heater does not work

asked by on November 15, 2016

Ok so my heater is inoperable. Check all fuses, good. Connected power to the blow motor that works. I'm getting power going into the relay but when I test it at the resistor I'm only getting a low voltage of 5 but 12 are going into the relay.Is this a bad relay or a ground problem

My car has 180900 miles.
My car has an automatic transmission.

Your vehicle’s blower speed selector controls voltage to the blower motor using two different circuits. When high speed is selected the blower control switch bypasses the resistor and operates the blower relay sending full battery voltage from the blower fuse to the blower relay to the blower motor. When tested at the blower motor on high speed, battery voltage should be present at the blower motor connector.

On blower speeds other than high, battery voltage flows from the fuse to the control switch then to the blower resistor. Depending on the speed selected, the blower resistor sends different voltage amounts to the relay which transfers that same voltage to the blower motor. When speeds other than high are selected, different voltage amounts will be present at the blower motor connector. Based on the information you provided, a ground circuit or the control switch and/or relay connections (internally or externally) could be open. If you would like a technician to come to you and inspect your blower system, please consider YourMechanic.

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