Ac conversation with factory AC

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brodrdude

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I have a 1975 chevy c20 LS swapped non a/c but has heater. I want to convert it to AC

I just picked up whole ac system out of a 1987 c30.

I know I need to cut square out for the box. But what else I need to do besides the wiring.
 
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CheemsK1500

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You will need to rig up refrigerant lines that work with the ac compressor on the LS, route vacuum lines for the blend doors and the control switch. you will also need need AC vent dash trim, and a instrument bezel for a 73-80, unless you want to use the entire dash pad assembly and Instrument bezel out of the '87.
 

brodrdude

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You will need to rig up refrigerant lines that work with the ac compressor on the LS, route vacuum lines for the blend doors and the control switch. you will also need need AC vent dash trim, and a instrument bezel for a 73-80, unless you want to use the entire dash pad assembly and Instrument bezel out of the '87.
I got an ac compressor relocation kit for top side imma being using an r4 style so I can use stock obs ac condenser and lines. For vacuum, can I use the vacuum port off of the throttle body?
 

brodrdude

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Well got the ac box all mounted. Need to do the wiring and vacuum and pretty much done
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SquareRoot

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Well got the ac box all mounted. Need to do the wiring and vacuum and pretty much done
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That easy huh?
 

SquareRoot

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So you updated your trucks ac from a 44 year old truck to a 36 year old truck? Nice. What refrigerant you planning on using?
 

brodrdude

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So you updated your trucks ac from a 44 year old truck to a 36 year old truck? Nice. What refrigerant you planning on using?
R134a what imma be running nothing special but I still need to wire up the interior
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brodrdude

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Interior and exterior wiring is done, now the vacuum and all the ac components in the engine.
 

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Finkaire

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Be sure to use an Ester oil and not PAG. PAG oil is a corrosive and will take out the original evaporator. Obviously replace the accumulator and orifice tube as well.
Best of luck!
 

CheemsK1500

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Later r4s made for GMT400 trucks are actually optimized for r134 (as much as an R4 can be, anyway.) I personally prefer to just modify lines to work with a modern compressor rather than make an R4 work though. Either route works in the end though.
 
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CheemsK1500

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I got an ac compressor relocation kit for top side imma being using an r4 style so I can use stock obs ac condenser and lines. For vacuum, can I use the vacuum port off of the throttle body?
As long as there is enough vacuum to run the blend doors, I don't see why you couldn't. Worst case scenario, you will have to set up a 12 volt vacuum pump to run the trucks vacuum actuated features. There were a lot of diesel trucks set up this way from the factory, before the industry started using electronic actuators.
 

brodrdude

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Got the ac compressor all mounted, new filter and dryer. Just need to mount up the condenser
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