Understand Blower Motor Circuits to Better Diagnose Problems (Season 5/E12)

A working blower motor circuit is set up on the work bench. Learn how the blower motor, blower motor resistor and other parts work so you can better test and diagnose your own car. See how to read simple wiring diagrams and avoid mistakes such as mixing up wiring diagrams for Canadian and US specification vehicles. (Tech Garage Presented By RockAuto.com | Season 5 | Episode 12)

[@robertleewhitt6241]

Outstanding, the voltmeter really made me understand > I’m replacing my resistor on my jeep 2006 liberty > the fan motor does not work on settings one and two, but works on three and four . It kind of works like a rheostat .

[@85beto85able]

Very helpful!! I’ve never used blue prints or schematics… I’m trying to fix blower motor today… just from this video I can tell the problem is the resistor!! Thanks again!!

[@jodilyon946]

Thanks to your video and explanation..youve got my business.

[@techseth]

My old blower motor use to blow so hard it’d melt the connections. The new one I bought from RockAuto is way less powerful, but I’m no longer replacing a connector every week. I’d say I had a unique problem

[@moniquewrites9046]

What if sometimes the air/heater works but sometimes it doesn’t

[@ryanwilliams3369]

Nice firebird you got back there.

[@94SexyStang]

Resistors can be repaired....you will usually find cracks in the wiring if you look close, you can re solder them....since each wire path is responsible for 1 individual speed, that's why you often lose 1 or 2 speeds at a time.

[@motivationindrive8514]

Soo what your saying is I should be able retrofit the big 12” style touch screens with climate controls built in into an older 2006 ram 1500

[@samuelanderson1415]

Thank you I have 2003 Lincoln town car I have to change my blower motor resistor

[@newvillage3]

I like this business model.

[@deankay4434]

My brother-in-law took his Ford Ranger to the dentist and bumped a parking lot curb. His truck started and he came back to our house. Later, it would start as it just cranked. I ask him about hitting anything, he remembered the dentist. The “Inertia” switch was below the glove box, I found it, pushed the button and started right up. Never failed again. Also, police and Highway patrol had a small paper guide to reset this device if they needed to help or move a vehicle. ASE Master Tech since 1978-Retired

[@williamgrissom9022]

The blower controls in my 1960's Chrysler cars didn't have a relay for "blower high" position, just routing that thru the switch. Result after a little corrosion was "melted switch". GM and Ford were likely similar. To mitigate that, I added a relay, as shown, so the "Hi" position turns on the relay, bypassing the high current around the switch. In some, the electrical switch was integral with a push-button vacuum switch, which costs ~$100, so melting one was to be avoided. Similarly, I added relay for "ACC" key position to keep that current off the ignition switch. Same issue in my 1985 M-B 300D, where I added a relay so the #8 fuse-holder doesn't melt (guessed it, "cabin blower"). In my 2002 Chrysler T&C w/ Automatic Temperature Control (digital) option, the "resistor" is actually a transistorized board, which I think does Pulse Width Modulation control of the blower motor. Like the resistor pack, it is bolted to the side in the climate box to sit in the air-flow (behind glovebox). When it fails (usually overheated), the blower usually runs on max speed and can't be adjusted (transistors usually fail shorted).

[@Idito0648]

Hello. Please tell me, if i switch (+) and (-) on the blowing motor, will it start run in opposite directions. I need this motor to run anticlockwise. All spare parts run clockwise.

[@Laurendoesflips]

Thanks for the info! I am gonna watch this later on :) I just repaired my window motor regulator by myself! :) It took some time to learn but once I got it was not so bad! Glad I saved $$. A mechanic came out and replaced my starter, but also removed a kill switch and modified my it to bypass the clutch switch without asking me :( :( and somehow made my car not blow any air and the lights to the heater do not come on or off either (it was all working fine before the "repair" he did)..so I think he ripped me off. So I am gonna go in and do this one or pay a much better mechanic to do this one!

[@COCODIYGAMER]

Great video

[@arealmaintenanceandrepairl1103]

Does that also effect the compressor say it senses blower resister is bad and it default to not let compressor run

[@jeffwebber4816]

What if I have 12 volts low to high at the new blower motor purple to ground and it still doesn’t work? I tested the new blower on the battery and it does work.

[@Fast_Forward_Racing]

My cars blower won’t turn on unless the car is in accessory mode (not cranked) and on high. If I crank the car it won’t work on any setting. I replaced the resistor and blower, but no fix. All fuses are good. The resistor has 4 wires, when in accessory one wire has power but when cranked that wire loses power and another wire has power. If I sent the current over into the other wire then the blower motor will turn on (and will work on all levels) but if I turn the car off it won’t work when I crank the car back up. This has me stumped, any recommendation? The car is a 2013 BRZ limited (automatic)

[@lens240]

Question. My blower starts then slowly comes to a stop and shuts off. After some time it will randomly run again then shut down again within seconds. Idea?

[@garethwood4715]

Could there be a simple explanation for a climate control system to be blowing when the ignition is off?? Many thanks

[@rustykuntz7423]

100% it’s the blower motor resistor

[@rustykuntz7423]

Sorry that these guys don’t answer comments and sorry that I was 5 months late on answering your question. Did you figure it out and if so, was it the resistor???

[@dalewilson4062]

Does the Blower Motor and Resistor have to match in order to work....?? I put a new blower motor on my 72 Mustang and it works on all speeds ,,,without the car running and a minute or two the glass fuse gets really hot and the switch gets warm...12 volt blower

[@Quintos.]

I got a land rover im working on when i put a test light the blower motor doesnt light up but when i put a multimeter on it the fans wiring harness says its getting 9 volts but the fan blower motor doesnt work but when you bench test it with 12 volts it works fine. The relays are clicking and it has a brand new resistor. I dont get it.

[@kevinbui656]

After blowing air for about 1 minute, My Mercedes clk430 blower motor stops. And the heater/AC control dash board went blank. Blower motor fuse is good, I replaced the resistor. I assume the fan motor is good, since it blows air when first started. What could be the issue? The Relay?

[@Quintos.]

Gotta love how we get no replys whatsoever from the dick who made this video huh

[@MrDrumHunter]

Hello and thanks for the great info!! I have a problem with my w202 c180 Mercedes 94' (code of the unit: A2028300785). Even if I remove the key from the car, the blower keeps working at maximum speed. Blower motor and resistor are new. I can't find why is this happening please help !!!

[@nathanbradforth3408]

My climate control unit has lost power as it won't turn on however the built in stereo still has power. It is 05 outback. Any recommendations? Thanks

[@NoneYa-mf2ys]

we you are right but if you system works on negative theory this won't help. What if your resistor only has power, ground, and signal wire? then the power flows through the motor to the resistor and then to ground. if the resistor is completely gone you will have power at the motor but it still wont run because the resistor robs it's ground.

[@papanutt2317]

I'm color blind. I have a 93 Mercury cougar xr7 WITH automatic climate control. I'm having to rewire the auto resistor for the blower motor and the new pigtail has all white wires. Hints to why I'm asking for help. When I got the car someone had cut the old pigtail wires off to try to put an analog resistor on the car but the climate controls in the cabin only work with auto climate resistor. Could anyone tell me which wire goes to which for the pigtail from the wiring harness? Any help would be appreciated. Thanks so much.

[@AliGan629]

Thanks for the video, but I you guys were explaining a little slower...

[@captaindeadpool1640]

I have power at the blower moter turn switch off no power this is the plug that plugs into the blower motor. So I thought bad blower motor so I went and bought a new blower motor and resistor for 2004 Ford freestar and it still didn't work I took the old blower motor and hooked it up straight to the battery and it worked 🤔. So fuses are good relay good resistor good and power at blower motor and defrost heat or ac nothing turns on the blower motor what could it be?

[@Happyfacehotwheels]

On rock auto's website where is the wire schematics located?

[@josepheklund8417]

How can you make the motor spin even faster?

[@samersarah957]

I got 1992 Toyota Corolla the blower motor does not work on third speed so the problem could be in relay or in resister? Thanks.

[@williamgrissom9022]

The highest setting usually doesn't have a resistor (your "third speed"?), so the problem is likely in the relay or its wiring, though that switch contact could be burned out.

[@malgers2005]

nice video sir

[@SBreeze]

I have power on my ground. And it doesn’t turn on unless I ground it. But I hook up the ground it doesn’t work. Hmm…

[@crystrezerex2life]

If that resistor goes out.....will you lose power completely to the blower motor?

[@davekapp]

yes

[@94SexyStang]

DEPENDS.......usually resistors only "partially" fail....so you lose 1 or 2 speeds.

[@geovanivela6733]

Hello RockAuto, thank you for the video. I have 2012 Dodge Durango that rear AC is not working. Do you think it could be the motor or it can be the resistor block? Please advice on what I can do to fix it, thank you very much guys.

[@jodilyon946]

Rewatch the video, gives u step by step to figure it out.

[@marcoflores4659]

I have.porch.cayene. don't. St a r.and the motor fan. 2.fans.star spinning. Like the motor temperature .is to high. I need. Help.tanks

[@BloodyMindset]

ON A NISSAN ROGUE I GET TO CONTINUITY TO GROUND FROM MY BLOWER MOTOR WHERE SHOULD I TAKE A LOOK? IM GETTING MY 12 V ON THE BLOWER BUT I HAVE NO GROUND?? IM WONDERING IF THE BLOWER IS GOING BACK STRAIGHT TO A GROUND OR IS IT THE RESISTANCE?? I TRIED A SENTRA RESISTANCE AND IT WASNT IT I GUESS

[@captaindeadpool1640]

The resistor is supposed to be the ground. Did you figure this out?

[@BloodyMindset]

@@captaindeadpool1640 yes thank you it ended up being a dead motor anyway :) just didnt want the trouble to get it out

[@99dynasty]

Can an issue with blower motor cause blower relay to keep failing? Blower motor works fine then fails and blower relay keeps failing

[@Ryder4u1313]

Why would it be a bad blower motor if it had 12v?

[@rustykuntz7423]

I assume it’s because if there was voltage that means your blower motor isn’t recognizing this and doesn’t work. Because if there was voltage up to that point, it’s safe to assume that the parts before that work as well? Idk man

[@captaindeadpool1640]

Because if you have 12 volts at the blower motor plug and it don't work than it should be the blower motor. But I have checked everything in my 2004 Ford freestar and fuse under hood good fuse under dash good relay clicks when I turn on air and clicks off when I turn off air resistor is good unplugged the blower motor turn on air have 12 volts turn off air have 12 volts so I thought okay it's my blower motor so I bought a new one put it in and plug it up nothing so now I am at a loss I took the old blower motor hooked it straight to the battery and it works so I am not sure why it's not working when I plug it up and it gets 12 volts when turned on. I even replaced the resistor that didn't help.

[@erickarpus3254]

@@captaindeadpool1640 did you ever figure it out? I’m having the exact same problem where my old fan works connected straight to the battery but not when plugged into the actual connector. I tested for continuity through both metal pins in the connector that plugs into the blower motor and the multimeter did not beep (meaning there is no a continuous flow of electricity) but there is voltage in the connector. So that means the ground must be bad, right?

[@captaindeadpool1640]

@@erickarpus3254 I gave up took it to a shop and he found a burnt wire and cut it out and spliced it together look behind the switch that turns the fan on.

[@captaindeadpool1640]

@@erickarpus3254 when you turn the fan on it should have 12 volts and when you turn the fan off it should have no volts also check the resistor it is to the left of the blower 2 screws hold it on you check it with ohms.

[@JoseMartinez-fz9kt]

I'm have Nissan armada send normal Air the dealership don't fane the problem

[@blatantmisconception]

Dude you're not paying by the minute here, slow down :D

[@davidfoxell333]

I'm alot smertter knoy

[@hammertimez717]

I don't think so Tim

[@andreamador3008]

. My rear blower motor fan always spins on low even if I turn the dial to high on the dashboard. So no AC in the back. I replaced the resistor but that didn't fix it. What else could it be? I have a 2007 Toyota Sienna CE??

[@andreamador3008]

What?