The A/C compressor will kick on and the system will run like that until the cabin gets to somewhere around 74 or 75 degrees, then the blower will gradually slow down to say 40% until the cabin reaches the set point temperature of 73 degrees. Normally, the fan speed changes only to maintain a selected temperature, but when the fan speed changes frequently and needlessly, there is an issue with the fan speed control unit. Models with dual climate control use the fan speed controller, and others use the resistor. I am leaning toward Resistor issue, but figured i would post to get everyones opinion. But you should still use a meter to verify good voltage. With it being winter, I've been running the defrost a lot... sometimes on full blast or … This one has been a big issue over the years. Use a multimeter to check for the presence of voltage in the connector with the key in the RUN position and blower speed set to HIGH. This happens in either ECO mode or normal mode and cycles down for about 1-2 seconds then blows full again. Please help as it is getting very cold out, and window will not defrost. Many, many times a car or truck will come into the shop with the customer complaining that their blower motor doesn’t work, or only works on high speed, etc. You should see battery voltage (12+). A: Blower Motor B: Blower Resistor C: Switch When I first turn it on it will blow perfect at the exact speed I select. My car … Often it will blow harder when I first start the car but slow down to a trickle of air within 20-30 minutes. If power is supplied to blower motor through the speed switch and blower motor resistor: Disconnect the electrical connector at the blower motor. After sometimes just a few seconds it will slow down and eventually not blow at all. I just purchased a Ram 1500 and have about 300 miles on it. Even when I set the speed manually it changes on its own, and it does NOT regulate the cabin temperature properly. Blower mtor on 1997 Chevy 1/2 ton 4wd runs real slow or not at all,some times it speeds up to near normal speed. If it doesn't blow full blast with the fan speed set to high, the chances are the fan speed controller/fan resistor needs to be tested. On the days it does work I seem to have no control over the fan speed. The blower motor relay is the electrical switch that is used to supply the power for the vehicle’s blower motor. Yes, it sounds like a failing motor. Blower motor decreases in speed as I slow down Hey all - search didn't really help me out with this at all so I figured I'd make a thread in hopes of getting some suggestions. Is there a relay somewhere? If you put the fan on the highest setting, it should blow on high no matter what. A bad motor can … The fan will only spin very slow at all speed selections from the switch. My car has 165000 miles. The a/c starts and runs then after about 2 miles it sounds like the blower will ramp down in speed then speed back up. It blows strong and warm. This is usually the case after a blower resistor failure on one or more speed settings. I have replaced the resistor pack, and the blower fan motor and no change at all. Yes, the blower motor is bad, replace it. By Rick Popely, Cars.com. At that point to fan will fluctuate up and down slightly to keep the cabin at the 73 degree set point. It is not the dual climate control model. If your fan motor no longer blows at the high speeds it used to, then it’s probably worn out from years of use or has other issues that limit airflow. When motor starts slowing down, give the the blower motor housing some banging with your hands and if the speed picks up, the motor is due for replacement. This is exactly what you say, brushes are worn. And down slightly to keep the cabin at the blower will ramp down speed. 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