The blower resistor is connected in series with the blower fan. Unplug the blower motor and test for power using the 12-volt test light in the same manner as explained in Step 1. Another symptom of a faulty blower motor resistor is no air from the vehicle’s vents at all. Changed blower motor. Test for ground at the blower motor if there is power indicated at all ranges, but the motor does not function. No Blow Checked power at the motor terminals and nada. The switch supplies ground to the different resistors in the assembly, depending on the speed selected. Testing the blower motor and the blower motor relay isn't hard. I have no blower at any speed 01 T&C Ltd with ATC. Lee Sallings is a freelance writer from Fort Worth, Texas. (Edited for answering.) Today it is a blower motor resistor for a 04-08 Ford F150. The added resistance in the circuit slows down or speeds up the blower motor as needed. The blower motor resistor harness connector has four wires, which supply it with the signals necessary for the blower to operate in the setting you wish it to. The AC will now blow cool air, it used to be really cold. Test for power at all the blower speeds by moving the blower speed switch through all positions. 05 trailblazer , auto( digital climate control) I bought it used and previous owner had hvac problems and installed a toggle switch to blower motor.i have followed the wires and there just to a b+ connection and cut blower harness which I have repaired. I checked all the fuses and they are all good. Found a burnt terminal on the power resistor connector. No blower replaced resistor, motor,and switch no power to the blower motor fuses are good. The voltage spike may cause a logic lock up in the blower motor control module that may be either momentary or permanent. I Can Switch From Vent, Max Ac, Defroster, And Get Nothing. Would it be safe to shunt/jumper/short the blower motor resistor, provided I am content with having the fan on full blast? By the way, I hot-wired the blower motor and it did work. No power to heater fan or resistor, i replaced blower fan and resistor and wiring harness that was shorting out,still no fan,replaced control panel for ity as well,was working just fine until that wiring harness messed up,now nothing, checked fusses in car and under hood,all seem good This means that the current running through the blower motor, and its’ speed is therefore controlled by the resistor value. The blower resistor is connected in series to the blower fan motor. The blower stopped working. On the resistor there Is 5 terminals. Basically, the blower motor ensures that the right amount of power reaches the motor, which spins the fan at the correct speed for blowing air from the HVAC system into the cabin. I have been testing to find the original source of the … Continue reading "2005 Chevrolet Trailblazer-No Power to Blower Resistor" no power to resistor or to blower motor. Changed resistor. He began his writing career developing and teaching automotive technical training programs. Power may not be making its way through to the fan. This means that the current running through the blower motor, and thus is speed is controlled by the resistor value. The fourth pole has no resistance and the fan turns at full speed. Disconnected battery to reset everything. The blower motor resistor is responsible for powering the blower motor directly. My blower motor won't come on at all. Let's start with the first test. the blower motor or the blower speed control module is bad. Attach the clip lead of the test light to a good ground like a bolt screwed into metal, and touch the sharp probe end to the terminals on the fuse. Consistant. I have read that sometimes its the ignition barrel. Ford blower motor resistor problems remain the most common solution to interior fan malfunctions on Ford cars and trucks. A faulty resistor loses power at different positions on the switch. Does this prove the resistor bad? I saw no mention of a 3rd fuse involved with the blower in the owner's manual. 2 c7 12bk high speed blower motor blower motor resistor c1 (mtc) - black 6 way cav circuit function 1 c75 12db/gy blower motor high driver 2 c74 12db/wt blower motor m3 driver 3 c73 14db/vt blower motor m2 driver 4 c7 12db fused front blower motor relay output 5 c72 16db/or blower motor m1 driver 6 c71 16db/br blower motor low driver A faulty resistor loses power at different positions on the switch. Consistent. I pulled the blower motor resistor and have no power to that any suggestions? There is no power to it? Power supplied from the fuse panel passes through the switch to the blower resistor assembly. Correction no power to resistor or fan motor. A blower motor without power will not be able to produce any air pressure, and as a result the heating and air conditioning system will be left with no air coming from the vents. High blower speed has direct power to the motor from the switch. Over time, the ground connection can become corroded or loose, causing the motor to function intermittently. 1 Answer. No power to the fuel pump. There are several symptoms that appear when the resistor of the blower motor is going bad. Step 1 – Check to see if power is getting to the fan. This is why at the bottom of the article we include a 2008 F150 blower motor wire diagram. The user chooses a suitable fan speed by using a selector to connect one of the resistors in the blower resistor pack. Locate the fuse for the blower motor in the owners/service manual. Blower motor resistors can wear out; the blower motor no longer works correctly if this occurs. it could be blower motor not grounded.your blower motor fuse and relay could be bad.make sure power is going to blower.motor.check to see if power is going to switch if so switch could be bad.hot wire blower motor using jumper wire and power from the battery.if blower motor works.you have fuse relay and switch problem.most the time when resistor bad.your blower motor only work one speed some time. If there is power indicated on high blower speed, but not low or mid range, the problem is the blower resistor. In the picture of my fuse panel they would be the top left two. Check for power at the blower motor connection. The resistor has power going to it but, the resistor may be burned out and no power is coming out of it. The blower motor power transistor is commonly referred to as the blower motor resistor when in the true technical sense it isn't a resistor. Tap on blower motor housing and see if it tries to move. The fan will now run at all speed settings. My blower motor wont come on at all. Copyright 2021 Leaf Group Ltd. / Leaf Group Media. Problems with a blower motor resistor are common in many cars. I Have A 2003 Crown Vic And Recently The Blower Motor Quit Working. If there is no power indicated on high blower speed, the problem is most likely the switch or the fuse. Most blower motors ground through the case of the motor when it is screwed into place or by a small ground strap from the case to the body of the car. First, I Went To Go To Work In The Morning, I Pushed "automatic... Blower Motor In 1999 Ford Crown Victoria Police Interceptor Not Working. Changed all fuses. Replaced relay-what now 1 Answer. Replaced the resistor, connector and blower motor. There is a relay for blower motor in junction box behind battery. Pull the relay and check to see if it's burnt. No power at the blower motor, no power at the resistor but I had power at the fuse box and the fuse tested OK. Then I pulled the resistor and here's what it looks like (the old one is on the left and the new one on the right): I'm guessing it's either a break in the wiring someplace or a faulty switch. With that said, failed blower resistor assemblies don't solve all of the possible failures. To test a resistor or motor, you’ll need to know the basics of electrical circuitry and have access to a multimeter and the proper electrical specifications for the involved circuits. Others may comment that the blower motor speed may momentarily drop or that the blower motor continues to run after the key is turned off. The most common symptom of a faulty blower motor resistor is a blower fan that only works on one speed, usually high. Testing at the motor itself eliminates the possibility of confusion caused by complicated electronic blower controls found in Electronic Climate Control systems. Also connected the motor to 12V and it worked, so I think that exonerates the motor. Within Two Days, I Had Several Electrical Problems With My '03 Cv Sport. This is due to the fact that the blower motor power transistor does pretty much the exact same job as the old style resistors of vehicles of the 80 and 90's. If it’s good, check for debris on the evaporator or heater. from what i atleast thought was the blower motor resistors, 2 wires coming from the blower motor purple and black go to a small board with aluminum finns on the back side, and has a small grey and larger black and red wires going into it aswell. It’s also worth noting that most vehicles have a circuit that bypasses the resistor when the blower motor is … turn the a/c on and rap on the blower motor a few times, if it doesnt work check for power at the blower motor, if it has power the motor most likely bad, if NO POWER then the module is bad. so randomly my blower motor stopped working on my 2005 monte carlo. Cause This condition may be caused by a voltage spike from the wiper motor. It is my understanding that at the highest fan speed, there is 0 ohms resistance upstream of the blower motor. What good is tapping on it going to do the resistor is seperate from the blower motor. If there is no power indicated on high blower speed, the problem is most likely the switch or the fuse. Replace the fuse as needed. Peugeot 406 heater fan/ blower dead, the motor works and both fuses work but there is no power getting to the motor. The user chooses a fan speed by selecting a speed which then connects one of the resistors in the blower resistor pack. checked fuse-ok. replaced relay-can jump motor and make motor run. This can be annoying, but troubleshooting is easy. Specializing in website content and design for the automobile enthusiast, he also has many years of experience in the auto repair industry. Blower motor is drawing too much power. High blower speed has direct power to the motor from the switch. The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting (4 or 5) and doesn't work at low speeds. There is power to the resistor but no power at the blower motor terminal. Also my door locks are really hard to lock and unlock the car- i have lost the key with the remote on it. Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues power can be cut off to the motor. When set to 80 degrees I still get the cool air. Mechanic's Assistant: Is the power loss consistent, or does it fluctuate? The resistor of the blower motor is responsible for transferring the electrical current that's required to move air through the vents of vehicle. The blower motor resistor (power transistor) now activates and lets a varying amount of Ground thru' to the blower motor. heater blower inop. I checked all the fuses and they are all good. 97 3500, 2 WD, G56, slightly bombed, 1.4 million miles with un-additized diesel fuel. This varying amount of Ground is what controls the blower motor fan speed. I'd like to fix it right, of course, but: 1. 3. Decreased airflow causes the blower motor resistor to overheat and fail. Mechanic's Assistant: What is the model/year of your Chevy? Hey guys yet another how to from a mechanics point of view. Blower motor fuse blows repeatedly. No power to blower motor. I did check the fuses with a multimeter, but only two of them. Test the fuse, with the ignition key on, using the 12-volt test light. He has written Web content for eHow, and designed the DIY-Auto-Repair.com website. - Answered by a verified Ford Mechanic Inspected all plugs to switches to ensure no melting. An indication of power at both terminals of the fuse determines that the fuse is good. The blower motor relay is the electrical switch that is used to supply the power for the vehicle’s blower motor. 2008 ford e250. Testing whether there’s power flowing to the blower in the first place is a good way to rule out a bad motor. If there is power indicated on high blower speed, but not low or mid range, the problem is the blower resistor. Blower motor resistor / control module problems. If one of the terminals has power and the other does not, the fuse is bad. 1983 Chevrolet Camaro Z28 Coupe RWD-General. Reduced airflow also causes the blower motor to work harder, draw more current and that can cause repeat blower motor resistor failures. If you start at the blower motor, and check resistance in the circuit, you will find the problem in no time. Really? I Am Not Good At All With Electronics, So Where Should I Start? Still nothing. Ground, signal, power, M-, and M+. I Get No A/c Or Heat Simply Air Flow. 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