I share Mitch's perspective. If you came in and asked for a charge, we would charge it. If we got wrapped up in every job, we would never make money.

But yes. The switch is open to the refrigerant on the other side, so you have to drain it to swap the switch. My A/C machine will charge without the compressor running, and it only takes 15 minutes to do an evacuate and recharge. Maybe you can check the shop and see if they'll cut you a deal to evac and recharge with you there so you can swap the switch right quick.

If there's pressure in the system, a switch should have continuity (a couple of ohms). If the system drops below 25psi on the low side the switch should be open (infinite ohms, no continuity).

If you have a trinity switch, two of the terminals should act as I stated above. The third is the activate wire for the cooling fan relay.


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Does anyone's vintage air make a quiet ticking from the condenser inside the cab when everything is turned off? My optima yellow top seems to drain faster than I expect, so wasn't sure if this was normal.

It's possible one of the actuators is being ran, but figuring out why might be more of a task.

I'd pull the batter cable off and use a multimeter to gauge how much amperage is being lost through a draw. You can use a test light too, but it won't tell you the amount, just that there is a draw (which if you have ecm/tcm/pcm/ect there will always be). Then pull the fuses for the vintage air unit and see if the the draw goes away or becomes less. If it does, then you know its the the a/c unit. If it doesn't, you can start pulling other fuses in the car until it goes away.

However, if the test light doesn't light up or the multimeter shows no draw, you just have a battery issue.