Cycling a/c or not?

[chevydog66]

So how do you make the a/c compressor cycling. Is it better or more efficient?

[cableguy0]

The compressor has to cycle. If it didn't cycle it would either blow the hoses open or the compressor itself. The compressor cycling is done through pressure switches.If it doesn't cycle your system will blow apart somewhere.

[chevydog66]

I have the POA update valve for R134 on my 72 GMC with 6.0 ls dbc. Sanden 508 compressor, but the rest of the hardware is original style for the truck. Do I need to install a trinary switch? If so where?

[clinebarger]

The compressor needs to be shut down at anything Below 15 psi on the Low Side.
The compressor needs to be shut down at anything Above 350 psi on the High Side.

On an Expansion Valve system the Trinary will mount to the receiver dryer. Yes, Every system needs a fail safe.

On an efficient, Properly charged A/C system.....The compressor should not cycle on a Hot 95+ degree day. But I doubt your system is very efficient if your using an R-12 tube & fin condenser?

[chevydog66]

I'm using a R 134 tube and fin condensor. How do I mount a switch on original style drier?
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[clinebarger]

I forgot the replacement driers don't have a port, You have a #6 hose running between the Drier & Expansion valve? Vintage has a "Crimp-On, In-line" trinary kit part# 24678-VUS.

I use Parker Receiver Driers & Aluminum Parallel Flow condensers only.

[chevydog66]

Thanks for the info. Do you have a part # for the Parker drier?
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[Clyde65]

Hey Clinebarger, give me a pm when you can, your PM's are full also
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[chevydog66]

The Vintage Air tech support line was absolutely no help. He couldn't tell me how to wire my Original type system.

[chevydog66]

The Old Air tech support guy told me I don't need a Trinary switch. I am running the clutch fan on my LS motor in the original truck shroud. The clutch cycling switch that is built into the POA update valve is all I need as long as high and low side pressures are correct. 150-250psi on the high side or 2.5 times ambient temperature, and 35-45 psi on the low side.

[clinebarger]

If your clutch fan is moving enough air across the condenser......He is correct.

[Blackpony]

mine is setup using the factory wiring and switches. it stays on all the time and blows ice cold! no problems thus far 8 years later....

[ls1nova71]

Originally Posted by chevydog66

as long as high and low side pressures are correct. 150-250psi on the high side or 2.5 times ambient temperature, and 35-45 psi on the low side.

And as long as you never get in a wreck, you don't need seatbelts..... But you never know. Personally, if it were me and I was putting together an A/C system that was anything other than a factory installed, completely stock set up, I would put h high pressure switch in it too.