A/C Triary Switch Question

[AusTx68]

I understand the triary switch serves to protect the compressor from operating outside the ideal pressure range (either too low or too high). It also operates the fan to keep air moving across the condenser. That being the case, if a system is fully evacuated how would it ever charge? The negative pressure in the system should cause the triary switch to open which kills power to the compressor. Right? Is this feature somehow bypassed?

This is purely an information question and not something I'm attempting on my own. I asked myself this question after installing my Vintage Air system. I plan to have it professionally charged next week.

[GMC Canuck]

When you first start to charge the system you don't need to have the compressor running. The vacuum will suck most of the refrigerant into the system. Once the pressure in the system and the tank you're filling from equalize , then you engage the compressor and slowly top up until the system is fully charged.

When you're getting your system charged, make sure they pull a good vacuum. The longer it stays on the vacuum pump the better. You're not just pulling the air out of the system, you're pulling any moisture out as well. Compressor oil is hygroscopic (takes on or absorbs moisture) so you're pulling moisture out of the oil as well. Moisture in the system combined with compressor oil creates an acid which over time is detrimental to the system. So it's best to keep compressor (I would say all, but mostly compressor) fittings capped until you're ready to make a connection.

[BrianV]

I know I have used a jumper wire to engage the compressor when charging theystem but in a lot of cases when the switch senses the freon it will kick the compressor on without. Using a jumper wire

This has been my experience anyway
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[tonypaul]

Off Topic-- But I think I saw you and your truck this evening @ HEB. You were rolling through, I was in my silver Lamborghini. I went in and got some stuff anc came out and there was a group of people around my car taking pics. I heard a killer thumping sounding motor, looked up and you were driving through.... Truck sounded killer!!!!!!!

[AusTx68]

Hey Tony, yea that was me! I saw your ride just as I was making my turn to leave. Damn I should have realized it was you. I would have stopped.
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[AusTx68]

So I had my Vintage Air system charged at Sears. They have this very cool machine that does it all without having to start the engine. It pulls a vacuum, runs a leak test, and pressure fills the system with the exact amount of freon specified by the Tech. The last step includes a manual dye additive. All for $125. Not bad

[tonypaul]

Originally Posted by AusTx68

So I had my Vintage Air system charged at Sears. They have this very cool machine that does it all without having to start the engine. It pulls a vacuum, runs a leak test, and pressure fills the system with the exact amount of freon specified by the Tech. The last step includes a manual dye additive. All for $125. Not bad

Did you have it done @ the Palmer & I35 location? I still havnt installed my A/C kit for my lambo yet but this Texas heat is killing me, I gotta do it soon...

[AusTx68]

Yea, that's the location. After I left Sears I stopped at HEB. Thats when you saw me.
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