A/C blower resistor - Toyota Yaris Forums

ubear7 · 08-08-2010, 07:28 PM

My a/c blower fan fluctuates at various times. Sometimes it does not turn on at all. When it does turn on it runs great and cold. I know that the a/c blower speed is controlled by the blower resistor through the fan speed switch. My loaded resistor voltage is 3.5v on 1, 5.2v on 2, 7.6v on 3, 12.1v on 4. My unloaded voltage is 14v. Is this correct or should the resistor be changed?

CTScott · 08-08-2010, 09:53 PM

Those sound about right. I haven't measured the voltage, but I have measured the resistance of the three taps on the resistor, which are 1.0, 2.0, and 4.0 ohms. The blower motor has a coil resistance of 5.4 ohms.

High completely bypasses the resistor, so if it sometimes doesn't work on high, then it's definitely not the resistor.

I would check the contacts on the blower switch and also the HTR relay.

08-08-2010, 07:28 PM	#1
ubear7 I've made a post! Drives: 2007 Yaris Join Date: Aug 2010 Location: miami Posts: 1	A/C blower resistor My a/c blower fan fluctuates at various times. Sometimes it does not turn on at all. When it does turn on it runs great and cold. I know that the a/c blower speed is controlled by the blower resistor through the fan speed switch. My loaded resistor voltage is 3.5v on 1, 5.2v on 2, 7.6v on 3, 12.1v on 4. My unloaded voltage is 14v. Is this correct or should the resistor be changed?

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08-08-2010, 09:53 PM	#2
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Those sound about right. I haven't measured the voltage, but I have measured the resistance of the three taps on the resistor, which are 1.0, 2.0, and 4.0 ohms. The blower motor has a coil resistance of 5.4 ohms. High completely bypasses the resistor, so if it sometimes doesn't work on high, then it's definitely not the resistor. I would check the contacts on the blower switch and also the HTR relay.