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The relay is just a switch that closes with a low amperage(current), 12 volt source from the dash A/C switch. When the the relay gets power from the switch, the relay closes and the compressor clutch is connected to a high current 12 volt source. The relay is there so you don't have to run highcurrent thick wires to massive switches on the dash.
So a basic relay will have 4 terminals(this one has 9). One is ground, one is switched 12 volts from the switch, one goes to the compressor and one goes to the A/C fuse where it gets high current power for the compressor. Additional terminals may provide power to the fan relay and other stuff?.
I am assuming that the compressor clutch disengages when you pull the relay with the engine running.
Since you have a Bentley, now is the time to learn how to read a schematic.
Since I forgot to look at my Bentley manual last night to check the configuration of the relay I am just guessing at some of this from looking at the relay. Pin 30 is the hot lead from power. I do know that 87 and 87b are contacts that get connected to 30 when the relay closes and one of these probably goes to the A/C compressor clutch. So to check the relay when it has been pulled, there should be no continuity between 30 and either 87 or 87b. If there is, the relay is stuck closed.
Without a diagram, I do not know where the rest of the pins go. What you need to do is follow the Bentley schematic and find out which relay pin is connected to the dash switch. My guess is that this pin is receiving current regardless of the dash switch position. Start the car with the A/C relay out and stick the plus(red) lead of you meter into that socket connector in the relay panel and the black meter lead to ground. If you have 12/14 volts, you know that the relay is always closed and hence, the A/C clutch will stay engaged regardless of dash switch position. Since you switch is OK, there is a wiring problem between the switch and the relay. You need to track this down.
The first thing I would do is unscrew the fuse panel and lift it up to see what's with the wires that go to the A/C relay on the bottom of the panel. Wires may be touching that shouldn't be.
If the pin from the switch is only hot with the switch pushed in, then there is another terminal that can close the relay when it is powered. Go through Bentley patiently and you will sort out where the power "is" when it shouldn't be. Follow and test each circuit one at at time so you don't get overwhelmed.
The A/C has a feature that cuts power to the compressor clutch when the engine is starting and i think there is power going through the relay continuously to the light in the switch.
posted by 216.75.9...
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