1978 Delta 88 w/350 V8 and A/C

First time dealing with HVAC. Blower motor is bad

The blower motor assembly on my car has 2 terminals (see pics)

I bought a new AC/Delco unit, with the blower wheel, that is supposed to be the right part for my car… but it came with just 1 terminal (see pics)






I’ve been unable to find a complete blower motor assembly that is similar to the one in my car…. Only units with just 1 terminal

I’m hoping to find a complete assembly that will work… if not I guess I can buy just the motor itself and put it in the unit I have….

Please let me know if you can point me in the right direction here

Thanks!!

 

If that second terminal is connected to the motor flange, then it’s just a ground. You could put a spade terminal under one of the mounting screws and get the same result.

 

The terminal that the black wire attaches to comes off with the screw and gets reused.

 

Thanks guys, very helpful. The second terminal is just a ground.

So I installed it no problem last night... but the system is still not blowing. Nothing. Nada.

There's good power to the motor so I assume it's the switch / assembly / controller inside the car ..

I'll dig deeper after work

 

If there is ""power", specifically battery voltage to the motor jumper the ground to the motor to a known good ground and retry. Not the wire but the clean paint free ground tab at the motor. If there is battery voltage at the motor the switch is working. If you have power to the motor and a good ground it will run unless the motor is bad.

 

So once again demonstrating the folly of replacing parts without first doing troubleshooting.

Start by running a jumper wire directly from the battery + terminal to the motor power terminal. My money says that the old motor was fine. Also be sure that ground wire makes good contact. The motor bolts to a fiberglass case, so obviously there needs to be a ground wire.

Assuming the motor works with a jumper, look for a square connector in the harness located between the distributor and the heater valve. This connector has four cavities but only three wires and connects the HVAC harness to the engine harness. The heavy red wire is the power feed to the blower motor and due to GM using undersized terminals, this connection frequently goes bad and overheats.

 

Thanks Joe...

I did say this was my first time dealing with the HVAC on this car. And I did say I tested the voltage to the motor before I bought a new motor.... so maybe not total folly...

I'll jump it to make sure and then go down the path you suggest

 

Did you actually test the motor itself? The problem with testing for voltage - especially if you are using a low-impedance voltmeter, is that you may get an indication of 12V but no idea if the circuit can carry the current under load. In the case of the bad connector I mentioned, testing will frequently show 12V with no load on the circuit, but as soon as the motor tries to draw 20A through those terminals, resistance prevents it and the motor won't turn. This has nothing to do with HVAC, it's basic electrical circuit troubleshooting.

 

Keep the OEM motor for when the chineasium crap you just bought fails next week.
With solid troubleshooting with a VOM you'll prob find a blown fuse(s), blown resistor assembly, bad switch on the dash, or just a corroded connection somewhere. YouTube Voltage Drop procedure.
No telling if the system had to seek its own ground path what it blew out. Make sure the ground is good and clean. Test the ground with your VOM as well.

A wire diagram is worth its weight in gold!

The resistor assembly is the gray connector with the yellow, green, blue wires right next to the blower cooling hose. Pull it observe and test the resistor curly Qs.

 

The blower motor uses a relay to bypass the resistor. If the blower isn't functioning at any speed setting, the resistor is unlikely to be the problem. When using a voltmeter, be sure to get a high impedance voltmeter to actually load the circuit (hint, the ones from Harbor Freight are not). A test light is also a good tool, since the light acts as a load and brightness (or lack) will indicate resistance. Troubleshoot by following the circuit. The two most likely connector failure points are the square connector I mentioned above and the single brown wire connector that provides power to the control head under the dash. Yeah, I've had corrosion and resistance problems with BOTH of those. Also be sure the ground terminal on the motor flange makes good contact with the flange. Rust or paint here will prevent the motor from working.

 

Be sure to scrape the paint off the area where the ground stud makes contact around the bolt hole. I was gonna point this out yesterday but didn't think I really needed to say it.