AC cycling Switch

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Pauly1119

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You really should try using the OE service manual , the system operation is spelled out and easy to understand/ learn. Not to mention the wire digrams would be extremely helpful since yours is modded. Have thought about a idle kick when compressor cycles?
Idle kick? I’ve never seen that with a carburetor. I do still have the original fuse box under the hood but that’s about all that’s left but most of the fuses in it have been removed. I have a system under my dash that controls most accessories but had nothing for AC. I pulled it out tonight to look it over.
 

Pauly1119

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I’m guessing it’s wired close to what AK49 was explaining to me, hopefully anyway. Looks like wires go from the controls to the fuse box.
 

GoToGuy

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A solenoid on the carb' flange when AC activated, would be activated also to raise idle slightly when compressor loaded engine, preventing to low idle rpm or stalling engine.
 

Pauly1119

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A solenoid on the carb' flange when AC activated, would be activated also to raise idle slightly when compressor loaded engine, preventing to low idle rpm or stalling engine.
How would I do that? Trinary switch? I was wondering if my fans will turn on when the compressor turns on too. I have 2 electric fans.
 

1998_K1500_Sub

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A solenoid on the carb' flange when AC activated, would be activated also to raise idle slightly when compressor loaded engine, preventing to low idle rpm or stalling engine.

Edlebrock used to sell such a kit -- the solenoid and bracket anyway -- for their carbs. It was up to the use to decide when / how to power it.

My 1979 Camaro OE carb had one on it, as many did in the day. The solenoid didn't "cycle" with the compressor clutch, it was simply on whenever the AC was selected, so there was still some hunting of the engine RPM when the clutch cycled (e.g., at a stoplight) but it kept the engine RPM from dropping lower that it otherwise would. It could be particularly annoying with an automatic tranny at a stoplight, as when the AC clutch cycled off and the engine RPM rose it would push against the brakes.

ECM controlled engines run SO much nicer, e.g., on account of load management and other factors.
 

1998_K1500_Sub

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How would I do that? Trinary switch? I was wondering if my fans will turn on when the compressor turns on too. I have 2 electric fans.

I would put the solenoid on the same circuit as the AC clutch, so it bumps the carb when the clutch engages.

I would power the fans through either a high-side pressure switch or a temperature controlled switch that senses the evaporator temperature. Either of those two is a good measure of whether the fans are necessary.

If you were to engage the fans at the same time as the AC clutch, the combined compressor and alternator load may be more difficult to manage / dip the engine RPM. But try it and see, if you like, that's the only way to know if it matters to you.
 

Pauly1119

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Hello, well I got the AC blowing ice cold and working but have 2 issues. First I pretty much know how to fix and figure out, the fan blows mostly through the defrost vent. I’m getting about 30% through the cab vents but the cab is still cold. Second issue is I did have to install a solenoid to kick the idle up but my idle is all over the place. The issue isn’t that it goes too high it’s that it goes too low sometimes. But only sometimes, when I turn the steering wheel it drops pretty low. My power steering pump also runs my brakes. Engine is a 383 stroker with a decent cam. Weird is sometimes it’s fine and other times it drops too low. I understand that when the compressor cycles it will go higher I’m okay with that because I have a pretty tall stall converter anyway. The issue is when it goes too low. Could my distributor need to be rebuilt? Can the weights be sticking?
 

Pauly1119

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Also my fans are always on, I have 2 electric fans. Also all the PCM’s are removed from this truck. It’s basically like a 1969 Chevy. I have a 383 carbureted engine run by a MSD ignition and a small drive system for the cab that runs my instrumentation.
 
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