Okay, on my car, I got the HVAC all set up, but without the AC yet. Everything worked great. A couple days ago, when I went to turn on my heater, it shut off the engine. However, it didn't just turn it off like a key, it was like the engine was forced to a stop, or the fuel was suddenly cut off. The blower motor works just fine without the engine running.

Later that day, I was screwing with it, trying various things and all of the sudden it works fine. The things I tried included removing the fuse, disconnecting the fan. When the fuse was removed, it didn't do it (but of course it didn't blow). When the fan was disconnected, it didn't do it either. This ends the possibility of a short, since it should still do it if the wire was shorting somewhere even if the fan was disconnected.

The following morning, I was driving (with the heat on) and as soon as I ran over the train tracks, the car sputtered again so I quickly turned the heat off then the car ran fine (without heat). Randomly, it started working later that day. This repeated for a couple days.

Today, I found my old heater only box and hooked it up. Car ran just fine. But as soon as I connected the AC blower motor, it sputtered and died. I then hooked up the AC blower motor from my other firebird, and it sputtered and died as well. I know it's not grounding itself, since the motor was in my hand, insulated from the chassis.

I tried was last time with the AC blower motor, but this time as soon as I turned it on, I gave the car lots of gas. It sputtered, but then after about half a second it roared back into normal operation and the motor was working fine. Then I realized that while the blower motor was running, the car ran about 50-100rpms less than if it were off. I turned it off then turned on my electric cooling fans. Those as well dropped the car about 25-50rpms a peice. Headlights did the same.

Is it possible under any circumstance, that the alternator would produce drag on an engine if too much current was being pulled from it? (such as the start-up of a motor). It should be the stock 105amp alt. When I had it off the car a while ago, it looked like peices of corrosion and dust fell from the inside, could this have anything to do with it?

 

No one has any idea? At least tell me if your car idles lower when you turn on the heater (but not AC), or if you raise/lower your windows.

 

bump

 

The alt is only able to place so much load on the engine, like the 25 rpm's you observed. If it seems to affect the engine as much as 100 rpm then it's not actually the alt being responsible, but rather a voltage drop in the wiring to the ignition/injection system. You could measure some voltages to verify this. The wiring responsible is shared with the accessories affecting the speed. Althoug I don't have the wiring diagram for your car before me, I guess the common wiring is a big red wire from the starter, going through a fusible link, and then the C100 firewall connector. If the connection(s) by the starter, and the fusible link(s) is ok, then I'd disconnect the C100 and inspect it. I think it's located behind the fuse panel.

 

Well I've had to pull and reconnect that connector many times due to adding wires to the system (It's a '90 MAP harness in an '89 MAF car, quite a difference), all the connectors looked okay, but I guess they could use a decent cleaning to remove some of that tar like substance. Thanks for your help.

 

hmmmmm bad switch maybe? or i its possible that the brushes are sending out some interference and one of your ecm wires are not properly insulated
and messing up the singal resulting in the spitting and sputtering. dose it make a diffrence if the blower motor spins faster or slower?