Bill Curlee

Well,,,, I cant guarantee it the issue but,,, If you pull it out you can use an ohm meter and measure each resistor circuit. It isnt difficult. Thats why its important to have and be able to use a meter.

Here is a schematic for you.

Munckhof

What a great thread, yet another on this splendid forum. I'm sorry to be offtopic but this... is... what... Corvette is all about!! A community of incredibly enthousiastic and willing-to-help people who are also very knowledgable.

Going further offtopic... owning an American car in Europe can be a bit of a frightening thought / enterprise as regards costs or parts + shipment and also regarding (specialized) service... but this forum in particular never fails to do away with any of such fears. So many solutions and if one isn't there yet it's given almost instantly upon asking. Major compliments!!

End of offtopic, back to lurking this thread and learning.

Ncognito

I agree, that is way above and beyond. Thumbs up .

To the OP, Congrats on the car and it looks like you have some great help getting it sorted.

I may get corrected here but on most cars when the resistor goes out you lose speeds and it will usually at least work on one speed(typically high). Is the c5 different in this respect ?

8vette7 is that the factory service manuals ?

csmoore88

I am about to go get what I need. I still cannot find a good step by step to access the blower motor and resistor. From what I have read I gather I just lay on my back in passenger floor and look up. 3 screws and catch what falls. I am 5'11" and only 120 lb so the tight space is fine for me, I am crazy thin. I just need to know for sure if the battery needs disconnected (- side), is the dash coming out,? OHM meter is only special tool? Torx screws? (I have no star or torx screwdrivers)

Thanks Bill and Chuck. This thread is becoming an electrical fiasco beat down! Serving american cold justice to an untamed beast that thought it would beat me. Together we should soon have her purring like a kitten...🙏

Macleod52

That resistor looks almost identical to the one in my '99 Grand Am. It was a common problem for them to fail due to moisture. You would lose your 1-2 fan speed. They revised the part and the new circuit board was all black (I assume a protective coating). I wonder if it's the same issue with the vettes.

csmoore88

I got the ohm meter, the best one they have at AUTOZONE. I hope I can figure it out. I am looking at the instructions now and I found the OEM owners manual, thank God, and am using it as well. While I was there I went on and got the resistor and the torx drivers, what the hell I am gonna need them eventually right (?), While I have it apart I am going to go ahead and check the drains. Are there any other drains or udders that need to be checked? I have seen minimal signs of water intrusion, but signs nonetheless. My first and only water problem happened when the window was left down in a downpoor but seeing signs of previous water damage I am lead to believe there may be water issues I have not seen in this drought.


@BillCurlee I am hoping I can figure this stuff out but that schematic you sent is not a language I speak. I hope you are close b/c I am trying to learn this volt / ohm meter thingie deal and may (definitely will) need a little assistance. I put the "***" in ***-istance .

csmoore88

Yeah, I think you did. That sounds familiar. Sorry, there has been so much said here, and I have read probably 300 other pages of posts in the past week, that I get confused. Thanks though.


I am lucky! I get this meter, a equus INNOVA auto ranging multimeter 3320. It has no instructions just a link to a website for info. Well, this is no longer made so no instructions either. Now I am googling how to use a multi meter. I do not even know what settings to use. I will set it to ohms and touch it to stuff and hopefully it will unfold. As I said before, I am a curious fool in many ways.

csmoore88

I watched that top video. It shows me some stuff but my lack of basic electrical knowledge makes it very limited. I will just keep working and researching. I plugged in the hanging plug but nothing changed. I am taking out the motor right now and replacing the resistor. I will report back after. I am sorry for all the trouble. I will exhaust all my avenues of learning before I ask for help again. I am being lazy and exploiting your advice I think. I know better. Search, search, study THEN ask. That is the proper etiquette for a forum.

csmoore88

I am exhausted after spending all day under the dash of this car. I got the blower motor resistor out, it was cooked (will post pics in a bit) it had black spots and the green flaked right off. I was happy to see the new heavier duty resistor was made to resist moisture.


I put in the new one but no dice. Chuck (the great CHUCK) walked me thru using the meter to check results and find the issue. I was putting 12.3 volts to the resistor (large multi pin plug going in to resistor) but only 0.494 was coming back out (2 wire plug going into blower motor). We worked for almost 2 hours trying to diagnose the issue before I decided to exchange the "faulty" resistor I just purchased.


Ok, did that and the new resistor is the same problem, only this time instead of outputting only 0.494 volts it is scaling from 0-200 and starting over. This same strange behavior happens if I check the voltage on the larger plug that goes into the resistor. There are several colored wires, each corresponding with a particular fan speed. At each speed it should send lower/higher voltage to the blower to control fan speed. The red wire gives a steady 12.3 which is just the current coming from the fuse block, but every other wire puts out 0-200 and back. I am stumped. The ohms are steady at 0 on all plugs and pins.


I noticed behind the bcm there are 2 square, black multi pin plugs that are about 1.5 inches cube. one leads into another plug that has an orange wire that is obviously just clipped off. I only noticed because I saw a bunch of black tape back there and wanted to see what it was hiding. turns out it was just to group wires but they are the same colors as the ones going into the resistor and may be the problem.


How likely is it that the control unit is just bad? I still get HVAC NO COMM and the A/C compressor does not kick on either.


Sometime during all of this I threw a code, history now, 40-BCM B0605 H

csmoore88

This is the plug behind BCM on the far left against firewall/center wall that has an orange wire clipped.





This is the wire grouoings going behund BCM you can barely see the black cubed plugs.

csmoore88

My resistor. Yucky!!! Looks like i have a good spring or autumn car because i am thinking the fan will never blow again at this point.

csmoore88

In the interest of full disclosure and making sure all information is out there I will mention what I think to be an irrelevant and unrelated issue.


The DIC buttons from fuel down to reset are never all illuminated. the lights are dark / dim and sometimes on or off but never all at the same time. The center area for radio controls is the same. Sometimes numbers 6,5 are lit and other times it is 1,2,3,4, but never all at the same time. I am thinking maybe there is an outside chance that is all one unit and it is not communicating correctly with the pcm / bcm. However I get 00000 radio codes since I checked the grounds and fixed the plugs inside the passenger door.


Guys, it is Sunday which means I worked all day and will not have another second for a week to work on the car. I know I have been very needy and naggy on this car. I understand you have lives and other forum members needing you. I only post in hopes that it is documented and someone eventually finds time or that someone has an immediate answer no one has thought of. I appreciate you all so much. If it was not for this forum this car would have sold at auction 21 days ago for about $4500 so I could make a quick buck on a P.O.S. but you gave me hope and now I am a blower motor away from a car I have ALWAYS wanted. So, Corvette Forum members, I salute you. Thanks again!!! You ever come to sunny North Alabama and I will buy you all a cold drink on a hot day, or a hot drink on a cold one.

csmoore88

12.85volts now


Now, I had disconnected the BCM yesterday before I decided to re read the posts and threads regarding my issue. After I did I surmised that is not the problem and left the old one alone and moved on. I never hooked up the BCM that I found in the car. I momentarily disconnected the good, NEW, BCM that my tech installed at the dealership. I drove the vehicle twice today after I FAILED to get the fan / blower working. The BCM code has not re surfaced. I am super frustrated at this moment b/c I do not have the technical or electrical ability to diagnose this (seemingly small) issue and I just want the air to move in the vehicle.


As for this moment I am celebrating my daughters 9th birthday, she had her ACTUAL b day in Colorado on vacation and I promised her a b day party. I will not likely re visit the forum today but I do appreciate all of your help. If it was up to me I would spend every moment I have to diagnose and fix this problem but the real world often intervenes with my wishes. Thanks again. Please do not think that I just left when I was ready, I just have things to be done that are more important than this vehicle, my little girl is an angel and deserves my time.

csmoore88

I will ask the tech today if he can hook up the tech ii and make sure that he programs the correct RPO'S. Hopefully that is the case.....Thanks again. I am back at work now but will be doing a bit of internet digging in my down time today to see if similar problems have been resolved elsewhere. Thanks everyone, Chuck, you are a star.

csmoore88

I have figured out what the black cube is behind the BCM. It is the "High Speed Fan Control Relay" It is loose behind the BCM and has several wires running into a wire plug, this plug is pictured in a previous post and has an orange wire coming out clipped about 5 inches out.

----edit----
I have access to a (totaled) 1999 Chevrolet Venture van with a seemingly identical HVAC control unit. The ***** and buttons are identical. If I DID need a control unit, would this work?

csmoore88

I have now read 2 threads about the HVAC NO COMM code being linked to the ignition switch. I never would have thought they are related but hmmmm. Could it be that easy? In all reports the hvac system was unresponsive when the code was present. Once the switch was replaced WHAMMY it fixed the issue.

Thoughts? I can get one for about $87 at Auto Zone. I read Bill C's write up on how to repair one but it is beyone my ability.

Trios

Your car doesn't have dual-zone climate control. Only the dual-zone unit has a reason to communicate with the car. So, since your car has a manual climate control, there is nothing in the climate control for the car to communicate with.

Hence, no comms.

This is not a problem.

You need to jump 12v onto the fan motor to see if it runs; if it does, the problem is before the motor, if it doesn't, then replace the motor.

csmoore88

I was not hearing you until now, sorry Chuck I bet you are about to choke me for not getting it. I have 2 separate issues. No air, No comms light. Not related. Easy

How do I "jump"" 12volts. remember and do not get this electrical mumbo jumbo super easily.

Trios

Hrm. Earlier today (on this forum) I got called George, now I'm Chuck...

My name's Will, nice to meet you sir.

I haven't ever had to get to my vette's blower motor to try and jump power onto it, so I don't know how difficult it is to do. When I did it on my pickup, the blower motor was in the engine bay and I just used a couple of 12 gauge wires straight from the battery, which is generally considered bad practice due to the lack of any sort of fuse.

The gist of what I'm saying is covered by Chuck in this post right here.

If you wanted to do it properly, you could go to the auto parts store and get a 20 or 30 amp inline fuse and attach it to a long (10 foot?) strand of red wire, with a set of alligator clips (on each end). Then another long strand of black wire with alligator clips and no fuse.

Making sure the red and black ends aren't touching each other and the red side isn't touching anything metal in the car, attach the red wire to the battery plus and the black wire to the battery minus. Then attach the other ends of those wires to whatever it is Chuck said to attach it to in the post I linked. If the fan works, it should start blowing at high speed. If it doesn't, it either won't go at all or you'll blow the fuse.

Keep in mind, I don't know what the connector that Chuck refers to looks like, so alligator clips on the non-battery side of the wires might not work, you may need to push the ends of the bare wire into female terminals. Probably best to look at it first.

csmoore88

No, Chuck has been helping me. He will no doubt read this to keep up with my progress, that was for him. Sorry for the confusion, meant no disrespect.

Great to meet you Will, or was it George? Just kidding.....

I will try and figure something out. I am back in the work week and that means 6 days of 6:30 am to 9:30 pm being out of the house. Sunday will likely be the next day I have to tackle it. Thanks for the input. That may well be what I have to do.