TechConnect Ep.37 - How To Test A Chevy Blower Motor Resistor (DR775)
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- čas přidán 22. 07. 2024
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In this episode we get into how to test the DR775 blower motor resistor and its surrounding circuit. Proper diag is critical when installing a new blower motor resistor. Many times the resistor is not the root cause of the failure.
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Your head light idea of testing are most logical thoughts I ever seen. keep up the genius work. thanks
Hey Sam, thanks!!!
Mike Becker, Senior Instructor
Excellent job Mike! I as well as many others really appreciate you and the Wells team taking the time to put these training videos out.
Hey Joe, thanks for watching! All of us here really appreciate all of you taking your time to watch!
Mike Becker, Technical Services Instructor
Fantastic !
This video left me with no questions and I didn't have to hunt down a wiring diagram.
Thanks Mike
It's great you guys are making these videos to help others understand what to look for and the steps to take that lead to knowing for certain what the actual problem is. Great job. 👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍
Hey Wade Hicks, thanks for watching!
Mike Becker, Senior Technical Services Instructor
Thanks Mike - excellent as always. Gotta love the 6054 super test light - GREAT example of how a regular 250mA test light's results will be skewed due to lack of current draw / load on the circuit!
Thanks for watching Smitty, that super test light is my favorite! I'm glad you found the example useful. Its amazing at how it can change the idea of "loading a circuit."
Mike Becker, Technical Services Instructor
This was excellent and perhaps the best explanation I have ever had on this circuit. My blower motor (a 2009 Savana van 4.8 L ) was only working on high. Eventually it crapped out and I put up with it till winter approaching became an issue. Started with looking at the resistor. Found the connector had melted at the power (RD/BK) and also at the ground (Bk) Replaced both the harness connector and the resistor but only had speed now at 1,2 and 3. Hmmmm's. Checked the blower motor and it was fine (other than leaves in the cage that got cleaned out). Started to second guess my workmanship, perhaps the new aftermarket resistor was faulty. Found this video (thank you) and went back to look at the 40 amp in the fuse block and sure enough..now it was burnt. Replaced it and I am back to all four speeds. Interesting side notes on this vehicle. I didn't do a load test on the blower motor but likely, as it is vintage, it would be wise to replace it as well it is likely drawing more than it should be. An immediate subscribe and like for sure!
Hey Michael, thanks! Glad this video was able to help in your diagnosis. I agree, it would be wise to replace that blower motor. Thanks for subscribing!
Mike Becker, Senior Technical Instructor
This is an awesome video explaining everything thoroughly and efficiently. I like this guys way of speaking and teaching. Very nice job man. Explained everything in order for me to quickly diagnose my situation. I will be applying what I learned after work today in my 08 Silverado. I expect it to have the same principles applied. Thank you Sir.
Thanks for the kind words! I hope it all worked out on your truck.
Mike Becker, Senior Instructor
Great video Mike ! Not always got time to watch but greatly appreciated.
Thanks James, i'm glad when you have time you chose to watch our videos! :)
Mike Becker, Technical Services Instructor
That's a really cool way to test the blower switch without removing it. Thanks!
Thanks Tim! Glad you liked it :)
Mike Becker, Senior Technical Instructor
I really like that you guys do teach a lot without shamelessly "just" promoting your products. That's awesome. Thanks a ton for that, Mike and the rest of the Wells VE team.
Thanks Blocki! We are here to teach you how things work and how to do things right....and maybe subliminally promoting our product :) You don't know it yet, but you may just buy a Wells product in the near future because of this video. It's like MAGIC! :)
Mike Becker, Technical Services Instructor
Do you sell in Germany and have Euro car parts in stock? ;-)
But seriously, I like that the main focus is on the teaching part, instead of trying to promote your parts subconsciously with sentences like "To avoid comebacks, buy Wells parts.".
Yeah, looking at you Eric O. with your Dorman 100$ promotion video :P
We are not a direct retailer. We sell through parts stores and online. Your best bet would probably be RockAuto.com and Amazon if you have them available in Germany. On this channel we really do focus on the learning. We want everyone to be able to fix it right the first time!
Mike Becker, Technical Services Instructor
"On this channel we really do focus on the learning. We want everyone to be able to fix it right the first time!"
And that's what I appriciate a lot! Thanks a lot for that. Have a nice weekend. :-)
Cool thanks Blocki, you have a great weekend as well!
Mike Becker, Technical Services Instructor
Thanks mike..
Always good to know how these things work.
I have repaired these in the past after finding the open with an ohm meter
Hey Shaun, thanks for watching! Now you can apply this testing on the next one!
Mike Becker, Technical Services Instructor
I love it. Jeremy Polk's comment about being "CZcams Certified" is becoming very popular. Soon it will replace "ASE Certified". Mike, this was an excellent instructional video. The visual using the head lamp was memorable. I'm glad your able to do these videos, they help.
Thanks Wyatt! Sorry for blinding you with the headlight :) With all of the good trainers on CZcams now, it's a great place to learn!
Mike Becker, Technical Services Instructor
Nice video, very descriptive on showing us where to test on the schematic at the white board and then showing us the actual test on the circuit.
Thanks for your Videos Mike, because of this video I was able to fix my A/C. Thanks a Lot Mike God bless you!!!
Awesome video! Easy to understand detailed explanations and tons of info. Great job!
Glad you enjoyed it!
Thanks for watching!
~Ryan
Great video Mike its amazing how the engineers use simple circuits on trucks as opposed to cars that circuit goes back to the 70s where on a car it would be electronically controlled with a duty cycle command to a blower module cost and the fact that truck owners aren't as ? you know what i mean take care Mike keep em coming
Hey Mark, thanks for watching! This circuit is very basic, but there is an option on these trucks for a computer controlled variable speed blower. These trucks did have the option for automatic climate control. Fast forward 10 years and the majority of cars are all auto systems now...but they really aren't too much different to work on.
Mike Becker, Technical Services Instructor
Great Video Mike as always.
Thanks Mike!
Mike Becker, Technical Services Instructor
Video great. Very informative. Thanks for taking the time.
Thanks Mike, Glad you liked it!
Mike Becker, Senior Technical Instructor
Just watched this, proved to be my blower motor, thanks alot
Awseome, glad you got it fixed!
Mike Becker, Senior Instructor
Great demonstration Mike!
Hey Big Dog, thanks man!
Mike Becker, Technical Services Instructor
Great video. I really felt I like I could follow what you were saying.
Great video as usual Mike!
Thanks for watching Bob!
Mike Becker, Technical Services Instructor
Nice video n great explanation, thanks for sharing.
Hey GTO 55, thanks for watching!
Mike Becker, Senior Technical Instructor
Good job on instructions and knowledge
Well done video, learned a lot from it. Where can I find the specs sheet you mentioned, I looked on website but couldn’t find anything.
Awesome great video and thanks for shared with us.. I’m very frustrated with my Chevy Tahoe 03, only 5 speed works. I changed the resistor and it was same issue. I changed the climate control and same result :(. I already changed the resistors and same case … however when I turn the climate on between speed 1 and 4 in the dashboard displays “Service 4WD” any idea what could be the issue ? Thanks In advance
Awesome video, smart young man. I lost 1234 speeds and only had 5z so I replaced resistor and now I only have 1234 and lost 5
Bringing it back to NAPA and hopefully next one will work.
Thank you so much! Good luck, hope the next one works!
~Mike
@@GoTechTraining Tried 3 new ones and all had no 5th speed, then they pulled one out that had 4 screw holes instead of 2 that is supposed to be if you have automatic fan speed sensing and it worked so I bought it. $45 more though.
Back again and enjoying the video.
Sometimes I think that a real time savor would be to replace the problem sensor like I did after my code 53 which is a high voltage spike
My engine is running rich and it's a 94 GMC Sierra C3500 automatic 7.4... After changing the cap and rotor, spark plugs and wires. It was running rich and the spark plugs where black and the cap was more than1/4 of an inch.
The last time I drove it the tailpipe came off the the catalytic converter. I reconnected the exhaust system.
Watched a video on running rich and had a trouble codes for 34, 35, 45, and the last one before the engine stopped and would not start again until I replaced my fuel pump relay that shorted out.
I also replaced the knox and temperature sensor
Thanks again for watching Michael!
Mike Becker, Technical Services Instructor
Thank you Mike. Great explanation!
Hey Jakollz, thanks for watching!
~Mike
Hello,
My dad has a 2005 Escalade climate system seem to have a life of its own.
It runs on full blast regardless of if you turn the fan speed up/down, it also stays on after turning the car off, and it is only blowing hot air regardless of what you set the temperature to.
I tried taking the resistor out, but its completely different than the one shown here, it only has 3 pins and not the 7 pins that the one you show in this video has.
Do you know how to diagnose this one?
After googling around I found people saying its the PCM thats fried, however I am not able to find any PCM part number, or anything on how to diagnose the PCM.
2007 gmc sierra .blows a fuse when a heater switch on 4. resister and blower wires disconected heater switch only plugged in. 4 still blows fuse.faulty heater switch control modual.?
I lost speed 5. Replaced the resistor and still nothing.... fuses all good, put a new blower yesterday changed the switch panel 4 days ago. It has voltage at the blower plug. I have no way to check amps but I’m assuming there’s zero. What would cause this ? Also did the resistance test on the new resistor card and the numbers are a little off on 3/4 Not sore where to try next. A new card or what could cause the amps to drop off ? 01 Silverado
Great video
Can you please tell me what is the name of all fuses belonging to blower motor on Chevy express 2500 2007?
@Mike. I was able to fix my 95 Chev Van today with the help of this video. I even pinpointed the exact point of the continuity break.
On my resistor block its mainly exposed coils that form the resistors. There is also what appears to be a voltage regulator zener device and 3 capacitors. My guess is the zener clamps an exact reference voltage , say 12VDC. What do the capacitor do? "Cushion" the voltage spikes between switch changes? Your thoughts. Dorman part# 973077. Thanks in advance.
I have 2006 c230 mercedes. Security alarm battery went out. When it went out the horn on windshield wipers on windshield sprayer on light on . replace security alarm part. Now horn off windshield wipers off light stay on bright when key on. Test relay on windshield wipers relay good. Test relay circuit Q 30and 87 power 86 power 85 no power. Relay circuit L 30 no power 87 power 85 no power 86 power. Horn relay 30 power 87 power 85 power 86 no power. What should I do now??? Thank you for some help.
Outstanding brother
Thanks for watching Mike!
Mike Becker, Technical Services Instructor
Hi I have Kia sorento 2007 2.5 diesel motor blower not working.have replaced new resistor, replaced blower motor,checked all fuses and relays all ok. Power to all connections. But have used multimeter to check power to blower motor on testing I have power to both connection? When I unplug connection and test again only yellow wire is live?. Have run wire from earth on battery to black wire to motor blower runs fast so blower is ok. Any suggestions please. Alan.
I tested the wire that went to my blower mother and got nothing. Also, only two entry points on my harness lit up. My ac does not work at all. There's no power. What could be the problem? The resistor?
How do you test the actual switch on the console unit?
Blower motor works, new resistor (need to manually test this to confirm, but unlikely I have 2 resistors that don't work), relay is good.
That only leaves the switch, yet no one says how to test that. I'm not going to remove the head unit and guess.
I currently have a 12v ran directly to my blower motor with a switch so I can get some air through for defrosting, but it's not the same as when it was working correctly, fwiw.
Im lost ive changed it all and its still running i brought a new resistor and worked for like a week or so then it stopped shutting off when i get out the suv i got a blower motor also and i changed the heat and ac controler
My blower fan works at higher speeds, but no lower. That seems to suggest the fan switch as we know the blower works and the resistor would not let higher speeds if lower were missing. What is it about the switch that would cause this?
I've got melted connector on high speed position..2010 Chevy Express..Blower Motor good? What else could possibly cause this to burn?
I followed this pretty much step by step ended up replacing blower motor and resistor and still I had only 5 speed on fan I hooked up a bulb to blower motor wires and it was dim on 1 and brighter as I went on what the heck well the ignition on hot wire to hvac controller was only getting 10 volts even with truck running it only got 10 volts but fuse was getting 12 on ignition and 14 running. Long story short the wire to hvac had a voltage drop somewhere I ran a new wire and I have all speeds now. Make sure you have 12-14 going to resistor because if you start at 10 volts it will not work 1-4 fan speeds
Great Video!
Thanks Rabbit!
I'm a bit late, but thank you for making this video. Very informative and helpful, I'm about to go out and figure out what the heck is going on here with my car. Hah.
Hey Daniel, better late than never :) Thanks for watching!
Mike Becker, Senior Technical Instructor
Thank you Mike. Good job. Any plans for any electronically controlled blower motors. Various differences amongst OEMs and on how they operate to control blower speeds.
Hey Billy, you're talking "auto" systems? Sure, I think we can do something like that in the future!
Mike Becker, Technical Services Instructor
Nice job Mike
Hey thanks Richard!!!
Mike Becker, Technical Services Instructor
Very good video, thank you.
Thanks Kenny!
Mike Becker, Senior Technical Services Instructor
Hi My name Is Mike, My son went and got the resistor with out testing to see the problem. so I went on the basis of him telling me he watched youtube and said this was the problem. So I helped him and bought it for him and we installed it. we got nothing when we tried it. we started to smell a burning smell. We shut it off. when he went to touch the resistor it was smoking hot... So told my son we have to take out the blower and check it , and sure enough it was frozen... So we ordered the blower and installed it and now we have no power to the resistor. check all fuse's and there good. My question is dose the pos power come from the switch first? Im thinking we melted the switch control. Any thoughts??
Great stuff!!
Thank you, thanks you!
Mike Becker, Technical Services Instructor
great vid... and info...
Thanks!
Mike Becker, Senior Technical Instructor
Great video 👍
Hey George, thanks!
Mike Becker, Senior Instructor
Great explanation Mike
Thanks Rob!
Mike Becker, Technical Services Instructor
Great video and diagnosis Mike! Do you figure manufacturers run the circuit on high in case the resistor fails for safety reasons? Just like they would default mode doors on defrost...
Hey Nick, thanks! Yes, I believe it's a failsafe. In case of failure of the resistor circuit, speed 5 will still work if the relay is ok. This would allow you to have heat and clear your windshield. Very much like default mode on doors. Good comparison!
Mike Becker, Technical Services Instructor
as usual very good video
Thanks a bunch!
Mike Becker, Senior Instructor
My blower only comes on when it wants to. Once it comes on I usually need to keep it on high to keep it going. If I turn it to 4 or 3 , it runs but then fades out.
Thank you for the video it helped to understand that type of system. I do not have the parts in the video in front of me but could you have measured voltage across the resistors and then using the basic ohms law compute the current drawn by the blower? I am not sure test points are available for that type of measurement.
Hello,
Yes, that would totally work. You would have to be careful knowing the correct voltage to do the equation, as battery voltage changes frequently when a load is put on the battery. But definitely could work
Thanks for the question!
~Ryan Wilsing
Best video ever!
Hello Miguel,
Glad you enjoyed!
Thanks for reaching out and supporting the channel!
~Ryan
Nice work, I earned one more YT certification today! :)
Nice man! Gotta keep those certs up! Not everyone can wear that CZcams certified badge :)
Mike Becker, Technical Services Instructor
Wells Vehicle Electronics hey and proud of it lol, I'm good with it . Great vid tho for real.
Haha there is definitely some good training out on CZcams...I don't get why so many people still make fun of it. Thanks for watching man!
Mike Becker, Technical Services Instructor
I had melted connector and replaced it and resister and have zero speeds, changed the blower motor and still nothing
Hello Mike I have replaced three resistors and three selector panels and I still do not have number 5 high speed fan in my 2004 Chevy Silverado. What would be the cause of that?
Speed five sometimes runs of a separate higher amperage fuse than the first 4 speeds. I would take a close look at the fuse box for any large amp HVAC, Blower Fan fuses
Quick question for you if you have the time. I was recently diagnosing a Toyota for a blower motor that had very low speeds on high. After doing some checks I did a resistance test and found the motor had under an ohm of resistance. I found a known good and that also had the same resistance. Shouldn’t blower motors have some significant amount of resistance? Thanks in advance!
Hey Franky, I'm not a big fan of doing a resistance test on a motor. We would want to look at amperage draw on that motor.
Mike Becker, Senior Technical Instructor
NGK Technical Training makes sense. Thanks for the response!
Just bought a 2003 Silverado and my fan runs on 3 & 4 only? Could it be the relay and something else?
Hey Wayne, sounds like it could be the resistor, or the control switch.
Mike Becker, Senior Instructor
mine high speed does not work the blower works then does not work..ajust the steering wheel would make it come on sometimes..then nothing..
My blower motor wont run but my radio speaker will not make sound either. I have a rodent problem and found they were running through my car after they chewed a hole by an interior wiring harness. I have removed the facial material of the dash, pulled radio, climate control etc. I see no chewed wires. Would the fan blower have any connection to radio's sound output? Those are the only things not working, no sound no fan blowing.
Also all fuses are good.
My blower motor seems to work on my avalanche even with the switch off and it is not the automatic control could it still be the resistor
Watching the video the Instructor mentions if the resistor is stuck (melted) in the high position it will run through the 30amp fuse continually and possibly even with the engine off. So I would say yes this could be your resistor. But keep in mind I am a student as you are so please keep that in mind.
I got a chrysler vision 1994 ...so my problem is when i turn the key on the blower motor goes to hi speed with out touching speed control and there is no speed control at all it stick on hi ???? could you guys give me some answers pls ????
Hey Mr. Flirt, high speed blower operation is usually the default setting. Take a look at the blower resistors circuits. It's possible that it's fried.
Mike Becker, Senior Technical Instructor
@@GoTechTraining thanks...
Good job Mike explaining how the blower motor system works. This comment is late so there will not be any yoga pant suggestions at this time. haha Take care -Glen
Better late than never :)
Mike Becker, Technical Services Instructor
Speed number 5 wasn't working on my 2004 gmc. Then one day it just quit working all together. I replaced the resistor and put in another speed controller...the motor will work when you put 12v to it. So..I done all this and still doesn't come on..what else could it be...I've checked fuses
Hey John, have you verified the ground path? How about the relay that runs the blower motor?
Mike Becker, Senior Instructor
@@GoTechTraining where would that be
I would also like to know
I just tested the blower motor right to the battery and it did nothing... went and bought a Carquest blower motor tested it at the battery and it also did nothing any help will be greatly appreciated
Hey Lars Bambi, what kind of car are you working on? I'll take a look into it.
Mike Becker Senior Instructor
@@GoTechTraining same problem here
Hello my friend I am from greece and I want your help. I have a skoda fabia 2002 and I have a problem with Blower Motor fuse. I change the resistor but nothing. Can you help me please
Hi Andi, you may want to take a look at the blower motor itself. If the fuse is blowing it's because of a high amperage draw. A worn out blower motor could definitely cause that.
Mike Becker, Senior Technical Instructor
@@GoTechTraining thank you!!!
what do i do if my relay only has 5 wires automatically controlled 2005 GMC Yukon sl
William, that Yukon shows to use a similar setup. 3 relays are controlling the 2 fans on there. Diag should be very similar to this video.
Mike Becker, Senior Technical Instructor
@@GoTechTraining ok thanks. turned out to be the motor resistor.
Great, glad you got it fixed William!
Mike Becker, Senior Technical Instructor
What's the name of your website
however . how do you test or if you have a diagram of the AC fan control.. i belive thats where the problem is..
That will depend on the system. Most basic fan switches are just a basic path through. The current travels through them to the resistor.
Mike Becker, Senior Technical Instructor
but a schematic or pin identification would be great to diagnose a bad control unit or broken circuit...
Thank u mike
Hey Upkar, thanks!!
Mike Becker, Technical Services Instructor
if this went out would it cause my suv to overheat
Nope. This is AC related. You're thinking of the radiator fan. If that went out then it could if sitting in a parked position because there would be no air movement through the radiator causing the coolant to overheat thus overheating your engine. If the fan is blowing it could be a bad thermostat that would block coolant flow through the radiator. If it was stuck open then your engine would never reach optimal operating temperature and continually run cold. Hope this helps @GlasSman_859.
First! Nice video & explanation Mike.
Heyo! Nice! Thanks for watching Zib!
Mike Becker, Technical Services Instructor
Great
My blower motor not working replaced restore control fan still not working fuses good
Hey Tom,
What kind of vehicle are you working on?
@@GoTechTraining 04 Silverado Z71
Hi Tom,
The first thing I would check is the blower motor and resistor connectors for any damaged or melted terminals, If those are ok, make sure you have power to the HVAC and Blower fuses. Ignition switches are common to fail and cause no power to the HVAC system.
~Ryan
Check all and changed all no power to controls
Hi Tom,
If you have no power to the HVAC control, and both HVAC fuses are good, the under hood fuse and the I/P block fuse. I would check the output of the ignition switch. If that is ok it has to be a wiring issue from the fuses to the HVAC control.
~Ryan
Could not find specs at web site called customer service and Paul says wells has no such specs available 😡
Hey Earle, what specs are you looking for?
Mike Becker, Senior Instructor
The fuses don't power anything do they?
What do you mean Jim?
Mike Becker, Senior Technical Instructor
@@GoTechTraining You said several times in the beginning of the video that various fuses provide power. Is that what you are saying or is it that they limit power. I am a newbie here and just want to be sure I understand. Thanks
Ahh I see. A fuse is a protection device in a circuit. It allows power to flow through it from the power source to where ever it's going. If the circuit draws too much current (above the rated limit, 15amp etc.) then the fuse blows and does not allow power to flow into the circuit. Make sense?
Mike Becker, Senior Technical Instructor
@@GoTechTraining Okay, I was just misunderstanding what you were saying. Thanks
Can't see where I'm going, that light is sure strong.
Never CZcams and drive! You never know when a headlight may blind you out :) Thanks for watching Tom!
Mike Becker, Technical Services Instructor
With my own tune up and couldn't figure why she wasn't still running correctly turned out to be bad new AUTOLIGHT SPARK PLUGS on two cylinders. It cost me $100 for that information.
Michael, did you know that Wells is owned by NGK spark plugs? I couldn't be more proud. Try some NGK's in there...you wont be let down!
Mike Becker, Technical Services Instructor
my blower didnt come on then it came on all the sudden today
Sounds like a possible bad connection
I would check the connection at the motor for burnt or bad terminals
@@GoTechTraining ill see how it goes i guess