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Thursday, July 9, 2009

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?


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.

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.



 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.  


 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.

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.

 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.

Hi Chris,

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


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


Anonymous said...

Just wondering if you found that the BLWR fuse was blown? My A/C works just fine, no problems at all, except when I put the dial in fan speed position 5. Then it shuts off, no fan at all in "5".

Any ideas what's wrong? Doesn't sounds like the resistor block to me. And the large green 40A under hood fuse is not blown.

It's 97 degrees today!

Thanks you for the help!

Sparky said...

If the 40 amp, green blower fuse in the underhood fuse box is good, then you have one of several things happening. Poor connection at orange or red wire at the seven wire connector at the blower resistor. A faulty relay within the resistor assembly. No power on the orange wire from the blower switch. No power on the red wire even though the BLWR fuse is good.

Christopher said...

So, I replaced the blower motor resistor on my Silverado, and a couple weeks later a friend was driving and smelled something burning just before the fan went out again. The resistor wasn't melted as before, and it was still getting current to the blower, so I went ahead and replaced the blower motor itself, but it still wouldn't work. Any ideas before I pay a mechanic to fix it?

Sparky said...

Install a quality Delco brand resistor. The poor quality clones have a problem with an internal failure of the ground circuit that travels from the seven wire connector through the resistor and out to the blower motor. We have dozens of cases of this happening.