2004 Chevrolet Tahoe, 30 Amp Blower/HVAC Fuse Blows

Hi Sparky,

Every time I put in a new 30 amp Blower/HVAC fuse it blows as soon as I turn on the control knob on the dash. I have already replaced the blower resistor and the connector that goes to it. I have now removed the blower resistor and cut off the harness trying to isolate the short. I then tried installing a new 30 amp fuse. It still blows this fuse as soon as I turn the blower knob to #1. It blows the fuse even though no resistor or it’s harness is connected. No wires are touching where the harness (Connector) was cut off. Could the problem be in the HVAC control head on the dash or maybe the relay under the hood?



Hi Nick,

Since you stated it was a 30 amp fuse I am assuming it is located at the driver's end of the dash. I would narrow the problem down by installing a new fuse with the key off. Switch the blower switch to speed 5 and then turn the key on and see what happens. I would repeat on each speed in the same manner. Doing so will hopefully tell you if the problem is with only one speed or with several. This will give us a direction to go in to look for the short.

Sparky

Thanks Sparky,

I did what you said and it worked on speed 5 and then 4. As soon as it hit speed 3 the fuse blew. Key off Replaced the fuse and pulled the temp control head on the dash . I then Checked each wire for continuity to the distant end at the module connector. I found the yellow and tan wire to be conducting to each other and to ground. I then slowly traced the wires back to the module and further on to the large connector at the passenger side access panel on the dash. This connector had several female connectors grounded to each other and to ground as I checked it with my meter. I began unwrapping the tape on the wiring harness behind the connector because the connector appeared to show no damage. About 6 inches from this connector, I found several wires melted together. I cut them out and soldered and shrink tubed them and taped them. Everything works fine so far. I am a little worried about how the wires became melted in this manner. I also noted that prior to reinstalling the blower resistor, it was hot to the touch. I hope this is normal. I put everything back together and on the way to work this morning everything works, all 5 speeds.  Thank you for you direction and help.

Nick

Hi Nick,

Although I have never seen it, I have heard of an issue of wires rubbing on a bracket around the glove box area.  

The blower resistor is designed to have air flowing across it to keep it cool. If it was not mounted it would get very warm. If  left long enough it would get hot enough to burn you and cause internal damage to itself.

Sparky,

No High Blower Speed 2002 Chevrolet Silverado

Sparky,

2002 Chevy 2500HD with manual air.  I lost only speed 5 on the blower and ordered a relay & harness from The Electric Connection and replaced this last weekend with no change.  The fuse was good under the hood but I changed it just for grins and it too had no effect.  Also, I cannot find a fuse labeled exactly "BLWR" but all fuses are good.  I have 12 volts going into the blower motor inself on all 5 speeds but it just quits working when the switch is changed to speed 5.  Could this be the switch?

Thanks for any help in advance!

Hi GH,

You have to have three things in order for blower speed number 5 to work. Ground on terminal "E" black wire, Power on terminal "F" orange wire and Power on terminal "G" red wire. Wire colors are for original wiring.  Terminal "E" ground id constant and terminal "G" power is constant. Terminal "F" power is only there when the ignition is on and the blower switch is set to position 5.

Sparky

Ok Sparky,

Power to terminal F is good when the switch is on 5. Terminal E ground seems good. Power on terminal G is good through all 5 speeds and when the switch is off. However, this is when it is checked with the harness disconnected. When reconnected, power to terminal G is lost when the switch is on speed 5. Using a test light and the harness plugged in, terminal G will go out when switched from 4 to 5 and not necessarily come back on when switched back to 4 even though the blower starts again. If someone simply pushes down hard on the underhood fuse and holds it down, the light will come back on as long as the switch is anywhere but 5. If you leave it alone and check a little later, it usually will light up again (terminal G) but immediately go out again when switched to speed 5. Any thoughts?

Hi GH,

It would seem that you have either a faulty fuse box,  fuse or a loose harness connection on the underside of the fuse box. Some fuse boxes have securing bolts that are tightened on the upper side of the fuse box and some have the securing bolts underneath. Either way they will have to be removed and inspected for damaged terminals.

Sparky

Sparky,

I've found the source of the problem.  I've attached a photo in case you run across this situation again.  Everything I found on the internet about speed 5 not working was either a fuse in the underhood fuse box or the blower resistor and mine was neither.  I was reading on the net that other people were having the same problem and nobody ever answered them concerning what I found.  Now my problem is how to fix the situation correctly.  Does the-electric-connection.com have a replacement 68-pin fuse box connector like the one in the photo?  If not, would this even be available at the dealer?  If not, would you get one from a junk yard or simply bypass the damaged terminal with an inline fuse?  The fuse box itself appears fine and if a replacement connector is advised by you, I know I would have to replace the one burned wire and its terminal and I am able to do so.  Thanks again for your help.  I will use the-electric-connection.com for all my electrical parts needs in the future due to the fabulous experience I've had!

Thanks,

Glenn

Hi Glenn,

I think that rewiring the damaged circuit to an external fuse holder will be the best option.

Sparky,

2005 Chevrolet Silverado, High Blower Inop

Hi Sparky,

I ordered a blower resistor and harness combo and two weeks after replacing it, the high blower does not work again. What could be the problem? All other speeds work.

Since all other speeds work we know that the ground is okay. What you need to do is switch the key on, set the blower speed to high (#5) and check for power on the red and orange wires at the blower resistor seven wire connector. Let me know what you find.

Sparky

Well Sparky,

I did what you suggested and found that the red wire was burnt. It started working as soon as I touched it. I guess I should have went ahead and changed the connector when I changed the resistor. I bought both at the same time but the connector looked okay.

Lesson learned. It is very difficult to predict if a connector will fail or not with this system. I agree with GM that the connector and the resistor should be replaced at the same time, regardless of how good it looks!!!!

Sparky

1997 Pontiac Grand Prix, Bower Erratic, Inop

Hi,

The heater / AC blower motor works erratically. It will not run on any speed except High most of the time.

However, even at "5" (Hi speed setting), it will not start immediately most of the time. If you set it to 5,

it may take 5 seconds or longer to begin running. Even after it is running it will not run at 4 or any lower

speed. Sometimes it did begin to run at a lower speed if you just left it there...it may start several minutes

later but was not predictable at all.

I am an electronics tech so have tried troubleshooting this situation. Initially, I assumed it was going to be

the "resistor" block since it at least always worked at high speed but got to where it never works on the

lower speeds. Then I got to thinking about this failure to start immediately on the high speed. I thought

if the motor "bearings" are getting bad, they may be resisting the startup on the lower speeds to where

it won't run except on high speed (with full voltage).

So I temporarily connected a new blower motor but it behaved the same way... runs after several seconds

of waiting, on high speed only. It doesn't run on any lower setting. I then checked for 12 volts at the connector

with the motor disconnected. It shows about 11.5VDC on the high setting and just a few tenths lower on each

lower setting. (I'm assuming with no load it is not showing the actual voltage drop on those lower settings

that would be normal with the motor connected).

So we know it isn't the motor and also not the resistors since it doesn't explain why the motor still takes

several seconds to start when on High as this should be applying the full battery voltage instantly. With

reading some amount of DC even through the resistors, they should not be an issue nor the series

hi temp fuse.

I noticed a relay "click" each time the blower switch is turned on so assumed it's contacts may be pitted

and responsible for part of the problem. After locating the "box" containing the relay, I noted there were

two other relays on the PC board which also contained 2-3 integrated circuit "chips" . The board had two

multiwire connector blocks which were the connectors for the cabling from/to this assembly.

I'm not familiar with this assembly. I have a "generic" diagram of the blower, switch, and relay but it doesn't show

any other circuitry involved. I'm wondering about the other components on this circuit board and if they are

involved in the function of the blower and it's turning on. I also noted that when the blower switch is turned

on to a low number, you hear the relay click on, but when up to the high setting, it clicks back to off???

Manually closing the relay contact seemed to have no effect on the motor.

So... after all this discussion, what are your thoughts on what is going on here and is this circuit board the

source of all the problem here? Is the circuit board repairable at a component level by myself? If I could get

the part numbers off the IC's, I may be able to change them as there are no other "active" parts on the board

and appears to be nothing overheated/burned.

The numbers found on the "box" with the relays were:

10097889 and 7156J These don't appear to be the GM part numbers and there were no other numbers found

except an insignificant one on the board itself.

Thanks for your support,

Harlan

Hi Harlan,

The first thing to check when the inop condition is power to the three fuses in the right hand fuse box. HVAC Control / 20 amp, HVAC Hi / 30 amp, DIC/HVAC 10 amp. The HVAC Hi fuse should be hot at all times and the other two should be hot with the key on. If all are okay the next step would be to check power and ground at the blower motor itself with all of the harness connectors in place. Let me know what you find and I will provide more info as you test.

Sparky

Hi Sparky,

Thanks so much for your tips. I have a wiring diagram of the circuit in question. After much troubleshooting, I did find the

supply voltage to the blower motor switch was very low to none! It at times would measure around 5 volts. Further checking

at the HVAC control fuse found the same condition at the SUPPLY side of the fuse.

I temporarily bridged that fuse to the adjacent fuse's supply (heavy gauge wire) and everything worked perfectly... all the

speeds of the blower switch functioned as they should. Oddly, with the fuse removed, the voltage on the supply side

would read normal but as soon as the fuse was in and the blower switch on, it dropped to nearly zero.

So the problem now is why and where is the 12 volt supply to this fuse losing it's voltage. There are two lighter gauge

pink wires on the back of that fuse block which carry the supply voltage. I have not been able to locate where they

originate due to the cumbersome wire bundle they run into. Apparently this circuit goes through the ignition switch but

then where does it eventually connect to the battery positive? With the small gauge wire being used (maybe 18-20 gauge..

which seems rather light for running a motor that consumes a fair amount of current) it wouldn't seem likely that much

arcing (corroding / oxidizing) would take place resulting in this condition in the switch.

Also you would think messing with the ignition key and switch position would have an intermittent result where

it would at times work at least to some extent.

If you can find the wiring diagram of how this fuse is supplied and where the supply wires physically run, that would be the

next step and a great help. At least then I could check the voltage at the input to the ignition switch to hopefully rule it out.

BTW... is the ignition "switch" removable from the key function itself... so the electrical switch could be replaced without

requiring a new "key / lock" assembly?

Thanks very much for your time and wading through this mess... been quite a struggle... aching back and sore neck from

crawling around under the dash, etc. :-)

Harlan

Good Morning Harlan,

As you stated in your first email, this has been an ongoing erratic condition that has gotten worse. The ignition switch is your problem as mentioned earlier. To check go to the ignition switch connector at the base of the column. It should make up the center part of a larger junction connection. Check both large red wires for 12 volt supply. If 12 volts is not present check the ignition fuses under the hood. If it is present and it most likely it will be then proceed to check the orange wire for 12 volts with the key on. It will not be there. Next jump the orange wire to one of the red wires and see if the blower now works properly.

The electrical part of the ignition switch can be changed without having to deal with the lock cylinder and key issues. It is fairly simple to change so don't be intimidated by it. You will probably have to invest in some torx bit drivers and sockets in order to replace it if you do not already own them. Any repair manual should show procedure but if you need help just drop me a line.

Sparky,

Hey, Thanks for the speedy reply... sure do appreciate it!

Well suppose it may be the ignition switch then if you're confident

there is nothing else in the "line" that would possibly limit the

voltage the way this behaves.

I don't have the car here now to look into it so will see what happens

when I try the steps you suggested.

Thanks again.. will try to let you know the results.

Harlan

Good Morning Harlan,

As you stated in your first email, this has been an ongoing erratic condition that has gotten worse. The ignition switch is your problem as mentioned earlier. To check go to the ignition switch connector at the base of the column. It should make up the center part of a larger junction connection. Check both large red wires for 12 volt supply. If 12 volts is not present check the ignition fuses under the hood. If it is present and it most likely it will be then proceed to check the orange wire for 12 volts with the key on. It will not be there. Next jump the orange wire to one of the red wires and see if the blower now works properly.

The electrical part of the ignition switch can be changed without having to deal with the lock cylinder and key issues. It is fairly simple to change so don't be intimidated by it. You will probably have to invest in some torx bit drivers and sockets in order to replace it if you do not already own them. Any repair manual should show procedure but if you need help just drop me a line.

Sparky,

Hello again,

After further troubleshooting, I did conclude as you suggested, the ignition switch is the entire

problem. I've never had this part of a car apart before so it was a bit challenging to get at the

switch area on the steering column. Managed to have something close to the necessary tools

to do the job but sure was a lot of work.

Another thing that made it more difficult was that the wiring harness to the connector block under

the dash needed to be reworked. I had tapped into about 5 wires some time ago when installing

a remote car starter. So I had to get that all out on the bench and splice those lines back into

the new wiring harness. Yes the switch is apparently only available with it's attached wiring

harness with black plastic connector block.

Well this has been a difficult one since I was hoping it would only be the blower motor at the

beginning but was really the ignition switch... can't wait to tear it apart and see what contacts

look like to cause this trouble. Also left in the new blower motor as it occasionally would squeal.

Thanks very much, Sparky and have a great day!

Harlan

2000 Pontiac Grand Am, Blower Problems

My heater & A/C control (fan) switch has 1 to 5 settings, but the fan only operates on 3, 4 and 5.
The car is a 2000 Pontiac Grand Am SE.
I would like to know if it is the fan motor, a resistor of some sort or possibly the switch? Also would like information as to where the problem lies and the procedure to fix it.

I viewed your Web Sites "2005 Chevrolet Silverado Blower Inop" and thought that was an excellent repair procedure.

Your assistance will be appreciated.

Nelson

Hi Nelson,

More than likely the blower resistor is the problem. It is located under the right side of the dash behind the glove box area. In order to test you will need to remove the lower hush panel and the blower resistor should be located next to the blower motor. Disconnect the harness connector and check for voltage at the yellow wire with the switch in position 1 and check for power on the tan wire with the switch in position 2. If powers are present the resistor is faulty. If powers are not present then there is a problem at the switch. Due to the fact that you stated that positions 3,4,& 5 work, this confirms that the blower and the blower relay are working. If you happen to find signs of water please make sure that you clean the a/c drain tube or the problem will return.

Sparky

1992 GMC Vandura, Rear Blower Location

I read the archives but didn't find an answer. I have a 92 GMC vandura 2500
and the rear ac blowers doesn't work. Where is the Fan for the rear blower.
I have replaced the front fan but I can't locate one for the back? s it
ducted from
under the dash ?

Thanks
Nick

Hi Nick,

If it is a factory installed unit it will be in the rear of the van, on the passenger side, behind the trim panels.

Sparky

1999 Buick Century, Blower Squeals

I  have a 1999 Buick Century, and every time  I turn on my AC or heater it makes this loud squealing noise. What could be the problem and how cheap is it to fix?!

Thank you.

Krista

Hi Krista,

Assuming that the squealing noise is coming from under the passenger side of the dash, I would say your blower motor needs to be replaced. I have included a couple of links that relate to your repair although they do not show how to replace the blower motor itself. The costs can vary quite a bit depending on quality of parts used and if you are replacing yourself or having some one do it for you. In my own shop the whole job would run about $250 + tax, using an original equipment blower motor.
http://www.sparkys-answers.com/2009/03/2000-buick-century-blower-will-not-turn.html
http://www.sparkys-answers.com/2009/03/changing-cabin-air-filter-on-2000-buick.html


Sparky

2004 Chevrolet Silverado, Blower inop

Hello Sparky,

 I have removed the Blower motor resistor (marke P/N 1530577) for inspection from my 2004 Chevy Silverado, 1500 V8 4.8L 294cid GAS FI N Engine truck. I have no console. When I removed the part a circuit board (which also appears to be cooked) came with it attached to the resistor body by glue apparently. When I refer to your pictures of the part to order, no board is shown. Can you explain this?

Chris

Hi Chris,
 Yes, we can explain. GM has redesigned the resistor and the harness connector. The original circuit board design you have has been updated to the current part number 15-81086. GM recommends updating the harness connector when the resistor is changed, our part number 4180. The new resistor will fit on place of the old one. There may be an extra mounting plate on your truck that has to be removed and discarded. You can see more details at the repair site address that follows.

 http://www.sparkys-answers.com/2008/07/2005-chevrolet-silverado-blower-inop.html

Great! I was on the sites and will order the part you specified.
I have one additional question. This truck was a field truck driven by our personnel in the dirt on a daily basis. It was a parting gift following my layoff. Anyways, filthy! When I rmoved the harness/circuit board I saw a vertically mounted filter in the housing (with the aid of a flashlight). Now, the cabin air filter has always been a thing of mystery for me (I drove 2 Z71 Tahoes prior to this Silverado and purchased a cabin filter but could not install it). I tried all manner of possibilities to access the filter in the Silverado. No go! I pulled out a shop vac and rigged it up to remove as much dirt as possible (it was caked on like mud and mudclods on the bottom of the housing!). Is there any other recourse for this? I dont really want to get a fan working and have the flow restricted by dirt. Anyway, Thanks again! 

Hi Chris,
 Indeed, this dirt must be cleaned up as this will damage the new resistor. Are you sure there is a filter there? The evaporator core can look somewhat like a filter to the untrained eye. If it is a filter it should come all the way to the edge of the evaporator housing and there should be strip cover held on by one or two screws. It is also made mostly of paper and will bend with your finger tip pushing on it. If the "filter" appears to be about and inch or two from the outer squared edge of the case then what you are seeing is the evaporator core. If it is indeed the evaporator core that is caked up with dirt, the best thing that can be done is to remove the evaporator core from the truck and either deep clean it or replace it. This is a very time consuming job. In leu of that the case must be completely dried out and then you will need to blow the dirt loose with compressed air and assorted length air guns and a vacuum cleaner. When you have as much out as humanly possible, do it again and again. The next trick is to park the truck down hill, spray a degreasing compound into the hole to coat the evaporator core and slowly rinse the case out with a garden hose. Make sure the a/c drain tube is flowing and take many breaks to allow the water to drain out so that you will not flood your truck. Also lay down plastic to prevent water from going under carpet, mat, seats & etc. You may even want to pack some towels around some things in the dash to keep them from getting any over spray. Do this as many times as you can stand and it should clean up reasonably well.

 Sparky
 

Sparky, 

 Thank you very much for your insight on this! I will begin stage 1 of cleaning this weekend (this should let the evaporator core dry sufficiently). I thought afterword, and will have my hands full as this truck was as dirty as I have ever seen.
I will return a message to you to let you know how it went. I think at that time I will add to the message boards in which everyone is asking if there is a cabin air filter, and in essence, out of sight out of mind. I think it is very important to clean this core up if that is all that is available from a personnel health as well as the health of the conditioning unit.
Thanks again. Talk to you soon.  

Chris

 Hi Chris,

 I forgot to mention a good way to dry the evaporator case is to turn the blower on high with the truck off and install a battery charger to keep the battery up. You could also hook the blower motor up to a separate battery if you wanted to. A few hours of the blower running on high and the engine off will usually dry one thoroughly.

 Sparky

Hi Sparky,

 Thanks again for all your time with this. I was able to get the evaporator very clean yesterday evening. I began by spraying the unit with Simple Green Degreaser and letting that sit for about 5 minutes. I then used a toothbrush followed by a heavy duty spray bottle to work off the gunk built up on the unit. This took about 4 cycles to get the core to the point where the heavy material was gone. I then parked the truck on an incline and used the garden hose and sprayer to blast out what was left and the junk that fell to the bottom on the housing. Again this took about 4 cycles. I had attacked the ventilation from the dash vent side when I first got the truck.
However, as dirty as I got yesterday, I feel that doing this helped the truck and my piece of mind about what i am going to be breathing in when I replace the resistor. I will keep you posted on the results of the entire job. Thanks.

Sparky,

 As a follow up to my earlier emails, I installed the resistor and harness i ordered for my blower unit. Works Great! And no smell from all that dirt that was caked on the condensor core. Fresh air!
The only thing that came up was when I turned the fan to full power (5 setting on the dial) it shuts off. I am happy with 4 speeds, but do you have any suggestions of what this could be?
Thanks for all our help with this, and in the past.
Chris.

Hi Chris,

 You have a blown fuse in the underhood fuse box. It should be marked BLWR.

 Sparky

Wo! Dude, you are good! I will check it out and let you know how it went... Thanks so much!

2005 Chrysler 300 No Blower

Hi Sparky,

 I have a 2005 Chrysler 300 with manual a/c and the blower does not work. I have taken the motor out and checked it with a battery and some wires and the motor works. What should I check next?

 For testing power at the blower motor, I recommend that the engine be running. Set the parking brake and make sure the transmission is in park. Now with a test light or a volt meter check to see if you have power at the dark blue wire at the blower motor. If you do not have power at the dark blue wire check the 30 amp fuse #42 in the right rear of trunk. If there is no power there with the engine running I will have to give you a test for the run relay. If there is power there, then go to the blower resistor and check for power on the black w/light green wire, with the blower motor connector plugged in and the engine running. If there is power there, you will need to unplug the resistor and check for ground signals at the harness connector coming from the blower switch. You should see a ground signal on the wires as follows: dark blue w/brown on low speed, dark blue w/orange on medium 1 speed, dark blue w/violet on medium 2 speed and dark blue w/yellow on high speed. If you have all of the switched ground signals then the resistor is bad. If you do not have switched ground signals I will have to give you a test for the blower switch.

Sparky

2002 Chevrolet Astro, Blower Inop

I have a 2002 chevy astro, The heater blower quit working, first the high speed quit then it all quit, what could be wrong? Thanks, Clay

1995 Chevrolet C1500 Blower Inop

My 1995 Chevy Silverado's blower motor, ac heat defrost etc... seems to keep loosing power. I took out the glove box door when it was starting to work intermittently and found the red and black power wires hot.melted the connector, so I checked the ground and hard wired the wires(removed the connector) Now its not working again? Help

No Blower 1992 GMC Sierra

The blower motor on my 1992 GMC Sierra extended cab truck ran only on high for a few days, and then quit altogether. I bought a new resistor, but I cannot find the location of the existing one to replace it. I removed the glove box, but could not see anything that looked like the replacement that I got from the parts house. Can you help me out?

1999 Dodge Ram Van , High Blower Only

 My blower motor only works on high when switched on.  Do you have a unit or a fix for a 99 Dodge Ram Van?

2004 GMC Sierra Blower New Blower Resistor Does Not Fit

   I have a 2004 GMC Sierra. The blower resistor is no good. I've gone thru GM dealerships and I have friends that work for aftermarket parts dealerships. The replacement resister does not bolt up and is similar but the bolt pattern and shape are slightly different. Is there also a new snap on harness that this resistor works with or am I getting the wrong parts?

No High Blower On 2005 GMC SIerra 1500

I replaced the blower resistor and repair harness that I got from your store and all functions returned except for high blower. Any ideas?

Location Of Blower Resistor on 1991 Chevrolet Blazer

Where is the location of the blower motor resistor on 1991 Chevy Blazer S-10

Need 2004 Chevrolt Astro Van Blower Resistor And Harness Connector

I need a heater fan resistor pack and wire harness.The plug on the harness is a 6 pin unit.The resistor pack is a sealed type ,rather than open coils.The 2004 Astro van is AWD.

How To Replace The Blower Motor On A 2002 Chevrolet Astro Van

Can you please help me?

I wish to find out how to take out/replace my heating/ac fan for my 2002 chevy astro van.

PLEASE HELP ME!!!!!

Thanks so much and I look forward to hearing from you.

2006 Silverado Blower Staying On

Sparky, Thanks for your site and all its great info!! I have the blower staying on problem w/ my 2006 Silverado. I have the 5.3 V8, bucket seats, and center console.  I needed the parts right away (its too cold!)  and picked them up from the local NAPA. The problem is my existing resistor does not have the big (7 wire) harness it only has three wires going into it. The parts I got do not match. Can you help me?

1995 Suburban Front Blower Inop

I have a 1995 Chevy Suburban 1500, 4WD Auto with buckets. The middle and rear ac/htr blowers work, but not the front.? I believe there are separate blower motors for each? Does the 1995 have a relay similar to the 2005 on the website? Any help will be appreciated. Thanks.