rigel

I guess that about says it. Have a 89 L98 in my otherwise 79...Thanks

SunCr

Assuming Manual Control of the Compressor Clutch and an '89 ECM (which doesn't control compressor engagement), you only need to concern yourself with two feeds. 12 volts from the a/c clutch circuit after the Low and High Pressure Switches but before the Clutch Coil to ECM Pin B8 for idle control. When the ECM sees the voltage, it'll bump IAC counts to maintain Targeted Idle. And a voltage reference from ECM Pin D11 to a fan switch on the High Line if you're using an electric radiator fan. Switch opens at 220 psi and when the ECM sees the reference voltage it drives the fan relay.

rigel

Your assumption is correct and I do have a 89 ECM. My issue is that I have A/C components from both years ( 79 and 89) and will have to purchase others. Liquid lines, and pressure switches mainly. So I am trying to get from a to Z without expending large amounts of cash. I would like to do as you suggest and in corporate the ECM into the finished system to control the idle when the AC is on. Thanks

Hooked on Vettes

Here's the schematic for an 89 with manual AC.

jeffp1167

If that compressor or clutch kicks the can they cost a small fortune for either part. I'm having to replace my entire compressor on my 90 and dropped a nut when I saw 400-550 bucks for it. I may try and mount a earlier compressor on my engine if it will line up with the rest of the serpentine stuff.

rigel

Thanks so much!!!

rigel

I am really torn between removing the A/C all together and fixing it. But I need to know what I have to do to make the A/C function first. Figure out how many millions it will cost and then try and convince the wife that is will be the last project for this year...yeah right....

SunCr

You can use any compressor if you're going to make up lines and want to spring for the right Accessory Mounts. You might even consider one of the Variable Stroke models (used on allmost everything GM makes these days). Less room - no cycling. High side on any system will need a cutoff; the variable stroke will eliminate the Low Pressure Switch. All require 25 amp fused power. Condensor size - more than the Evaporator - will determine how much gas it needs but charging to pressure (2.2 to 2.5 times the air temp at the Condensor) should make it chilly. More ideas may be available at www.hotrodlane.cc including Sanden models, favored by the Rodders.

jeffp1167

I put a F-body serpentine system on my 82 corvette and all its lines connected right up. Why don't you try a 85-87 vette serpentine system that uses the same kind of compressor as your car had.

rigel

You know what they say hind site is 20-20 and I got rid of the older compressor with my old engine. Right now I have the 89 compressor, and most of the rest are parts are from the 79.

rigel

Sorry but I missed your post earlier. Thanks for all the good Ideas.