I have a 87 coupe with electronic control. The blower motor would not operate. My first thought was it might be a relay as the compressor works and the a/c lines turn cold. So I did a search and found a thread that discussed a 86 and someone had posted a diagram of the location of a blower motor relay along with a fuse. I found the location and the fuse was located there but no relay (maybe this is needed for manual controls?). Anyway I then decided to remove the power line to the motor and see if there was any voltage. Sure enough there was. So I got a new motor and before installation I connected it up and it worked so I installed it. Started up the a/c and the blower ran for about 2 seconds went off and 2 seconds later ran again for a short time and then off. Nothing since. So my question is there a blower motor relay and if so were is it? If no relay then what? I have checked the fuses there are ok. Is it possible that the speed control for the motor is out and this is causing the motor not to run? Thanks for you help.

 

There isn't a relay.

Bolted to the top left side is a blower module with 2 harnesses attached to it. The brown wire is low voltage inputs from the control panel. About 2.5 volts for low blower speed, 7 volts for max. The module amplifies these voltages providing outputs of about 4 volts for low up to 12 volts for high. The output side of the harness is a purple wire (or at least the same color as the hot side of the blower motor).

Start by checking the input voltages. If there, the control panel is ok. Check to make sure the module is getting powered up. That's the red wire in the module harness which runs from a fusible link behind the battery. Then check the output to the blower motor. If everything is good, check the blower motor ground. It's shared with the module ground so you might have to dig around in the harness to make sure the splice hasn't failed. It terminates on the frame just below the evaporator case. Make sure it's clean and tight.

Finally check the blower motor connector. As the motor ages, it can grab a lot of amps dropping volts across the connector. If the wires are discolored or melted, you might want to take the connector apart and daub some solder on each terminal.

Hope this helps - once you check voltages, you should be able to figure it out, but repost if need more help.

 

There is a blower control module on the top of the evap housing. This may be the problem. Its $ 100 at the dealer. The good news is the same one fits a ton of GM cars. Go to the salvage yard and get one with the same connector. I paid the $100 and then found that out.

 

Thanks for taking one for the team
I'll keep that in mind if I need a cheap module

 

Thanks SunCr and Spankyellow you both have helped alot. Yep there is no rely but there is a digital blower motor controler. And mine is not working. I have a little trouble thinking about using a savage part so I will get a new one. Again Thanks.

 

Got the new part and all is working. While I had the part guy I asked him what other cars had this part. He did a look up and came up with this:
86 to 94 Buick
88-93 Cadillac
88-91 Pontiac Bonneville

There may be others but these are for sure. Look for the cars with electronic controls.

 

Glad you got it going. 95* here today. Probably the same for you. Got to have that air.

 

Quite a few really. Just go to www.acdelco.com and cross-reference the part #.