Hello my corvette-enthusiast friends, i need your help.

My A/C fan is not blowing any air into my cabin and i already spent months on trying to fix it.

It´s an C68 in a 1987 Corvette C4.

I found out, the blowermotor is not running.

I measured the voltage at the plug which goes into the blowermotor.

When i turn the ignition on there are 2,8V at the plug. The voltage does not change even if i go up to fan speed 10. Doesn´t matter which speed i chose, it´s always 2,8V.

If i turn the A/C off, the voltage drops to 1,3V. If i turn it ON again, the voltage starts rising! When i turn up the speed of the fan now from 5 to 6 the voltage is rising until it passes 9V. Everytime i pass 9V the voltage drops immediatley to 2,6V.


I checked the fuses, i changed the blower control module (original gm part), i checked the blower motor itself (it´s running when i attach 12V to it).

I read through batee´s website, i changed the two capacitors and still i have the same issue...

Now the moment has come where i don´t know how to continue and how i can fix this problem.



If the explaination is hard to understand, here i a link for a youtube video where i show the exact problem.

→
Does anyone have an idea what i can do to fix it or whats the problem?

Greetings from Germany
Max

 

Have you looked at the fusible links? See my recent thread with the power schematic for an ‘85.

https://www.corvetteforum.com/forums...ey-begins.html

 

You should definitely have a look at link and connections.
Fusible link “K”

 

Not to hijack, but can I ask what this illustration is from and if you have the matching power circuit diagram? Trying to figure out if GM changed the designated fusible link letters with different years, as these letters don’t match what I have down for an ‘85.

 

86 factory manual

 

The connections/plugs look perfect, i used some contact spray on them just to be sure.

the fusable link is something very uncommon to me. What should i check/see there?
I think it must be inside of the big tube where the blowermotorwires are going to.

 

Fusible link is a smaller gauge wire wrapped in a fireproof jacket.
Swollen and deformed shape is a good sign of failed or failing fusible link.

 

Ok, things are going very crazy right now. I haven´t found the fusable link K but i was very sus about the wiring which goes to the BCM so i wiggled it and i heard weird noises.
i hold the fusable link... or whatever that is, tight together and the blower started running, the wiring is getting a little hot and i decided to shut it down again before damaging anything.
I think i need a wiring diagram for an 1987 C4.

It looks molten.

 

I can’t tell if thats a terminal block or some sort of inline fuse, but that poor connection is most likely why you can’t get enough current to your BCM.

 

It was kind of an inline fuse. I´ve thrown it out and the Blower motor works... wow Months of troubleshooting and a few hundred euros because i haven´t found this.

Anyway, time to fix the wiring

 

So good to hear you have sorted out the issue. While you're in there fixing the wiring are you able to help me trace a few wires and vac lines so I can fix my cut loom? Same thread I linked with the diagram:

https://www.corvetteforum.com/forums...ey-begins.html

I found this photo of the loom removed on eBay. I'm trying to figure out the exact path after this 3 wire connector. It comes from the blower relay for the high speed fan and to ground it.

 

Do you still need the Electrical Diagnosis Manual for 1987? Check your PM

 

Is this one of those deals where it could be the programmer that's located in the driver footwell? I know I've had to redo that thing like 3 times. Mainly the two resistors. Last time I ordered a rebuild kit from Batee.