Hello folks. My name is Jason. I have a question. I have a 91 RS with a GM 350 330 HP crate motor and LT1 TPI intake. It was an original 305 TBI car. My question is after doing swap, when the motor is running, I have a bad drain when I turn the AC on. Within a few minutes, the car will totally die. What would cause this? Something simple I hope. Appreciate any help. Thanks

Jason

 

 

Maybe the bearing in the A/C clutch is freezing up? I wouldn't think that the A/C compressor would reduce power enough to kill the engine from it simply running - yes it would reduce power/idle, but to the point of killing the engine I wouldn't think, unless your idle is already set too low. But ya never know - anything is possible.

 

I appreciate everyones input.
I don't have the original ECM. I have the TPI ECM that came with it. The TBI ECM went away when I converted from TBI. The ECM was a plug and play. The box looked identical. Not sure how else to explain problem. When I turn on the AC, the battery / car very quickly begins to drain, almost like a bad ground. Had a bad cable coming off starter in my other car that touched the header and caused a huge drain. All connectors are good. Haven't checked the relays / fuses though. Again, thanks.
Jason

 

Oh - so do you mean the A/C makes a huge electrical drain?

 

Yes, a HUGE drain. When you turn on the AC, it immediately begins to drain and the car dies within a minute or so.

 

OK - I'm no xpert here, but - doesn't the A/C simply have 2-3 wires to it? There should be a wire to 'power' on the clutch, and a sensor wire to sense the high pressure for the rad fan to switch on, and this same wire would tell the ECM that the A/C is on and thus the ECM would increase timing and/or fuel mixture to increase idle. Beyond that, I don't think there's anything A/C specific related - and you'd think if any of those wires were drawing that much juice they'd fry.

Is the same drain present when it's just heater? Maybe it's the blower fan drawing too much juice? As I understand it, the relay on the heater box controls the high speed of the blower fan only, and the resistor that's held into the box with 2 7mm screws is what reduces the draw for the lower speeds of the blower motor. Maybe somthing is funky with that stuff? Is the blower motor relay getting hot? Or any of the wires to the blower motor?

Like I said, I'm no expert - but this seems really off the wall. Congrats! You've posted a problem I've yet to see on TGO in 5+ years! Hopefully another with more knowledge of the A/C system will chime in soon.

 

The drain only occurs when the AC is switched on. The AC doesn't make any weird noises when on. It blows cold air when it is on. Haven't had the chance to check any of the relays. My car is in NC, I'm in KS. I plan to fly out there next weekend to pick it up and drive it back. Obviously, I won't need the AC, what about the defroster? Car drives great other than that.
Thanks again guys.
Jason

 

I live in NC (Raleigh area), and I deleted the A/C on my car (love riding with T-tops out), so I think you'll live this time of year without it

Defrost - ehhh - keep a tshirt on the pass seat to wipe off any fog buildup.

If your car is close to Raleigh, and you think you'll need any help with anything when you get here, PM me and let me know - I'll give ya my cell number.

I wonder if it has anything to do with the cooling fan? The A/C automatically turns on the cooling fan to cool the car against the increased drag on the engine. And the cooling fan has large enough wiring to be able to draw alot of amps without burning up. Do you have a single fan or dual fans? Dual fan cars the secondary fan comes on with the A/C and runs as long as the A/C is on - single fan cars the single fan runs with the A/C as well. Maybe there's an issue with the fan wiring - I believe they run off a fusible link (which could be bad) that is activated by a relay for each fan (could be a bad relay as well I guess).

Anyway - let me know if in Raleigh and going to need help. I won't promise I can fix anything, but I can bring tools and help you cuss at it!

 

camaronewbie,

The cooling fan is hardwired to a 12v source so that it is on all the time. I wired it that way to deal with the harsh heat of Arizona.

I really appreciate the offer to help, however, I'm in the military and only have a little over a day to get back here to KS. My car is in Hendersonville.

Thank you all again for your help.
Jason

 

Yikes! Yeah, Hendersonville is probably closer to KS than to Raleigh!

 

Yea, looking at about a 20 or so hour drive. Should be fun. Thanks again for your help.
Jason

 

 

If I don't shut the AC off and let the car die, it will need to be jumped. Thanks.
Jason