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GL AC Compressor Mod....

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First... Holy Crap! I love the new format of the USMB!  Looks great!

OK. Every year, when things cool down here in California, for reasons of which I have no idea, on Murphy, the $500 87 GL-10 Turbo-Wagon, I disconnect the electrics from the compressor, rendering the AC system inoperable. Today, i hooked everything back up and the system is working quite well.


Here's the question.  On my 94 Legacy, when you turn on the AC, the compressor turns on, then after a couple of minutes it turns itself off, as the compressor does not need to run full time in order to provide a cool environment. I think they do this so that the fuel economy not be as bad if the compressor is not running all the time.


I would like to put some sort of timer control unit in Murph to make the compressor internittent  when the AC is on. Has anyone ever done this. Does anyone know where the timer relay is on the Leggys so i could pull one from the bone yard.

Thanks...  And sorry I haven't been around much. I've been busy with jobs and music and other nonsense!


Mike Alexander aka Sonicfrog.

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I know that there's a system in place so that cuts the compressor when you hit the gas a certain amount..maybe you could use that system some way to do what you're thinking?

It works that way so that if you say floor the accelerator, the compressor cuts off so that it's not draining any power from the engage, allowing you to get that pick up quickly.  You can actually hear it happening, and it doesn't even require full throttle. Even half throttle shuts it off IIRC

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On your Legacy there isn't any kind of timer, it's more indirect.  There is a pressure switch that when the pressure gets too low it will cut off the compressor for a bit until the pressure comes up.  Under normal operation if it's not working hard that switch will trip causing the compressor to cycle; this is normal.  It's possible that your Legacy is actually a bit low on refrigerant causing it to cycle more than it should.


Now on the GL-10 it has the same setup.  I suspect that the pressures are different enough to not trip this for some reason.  So you could play around with the pressures, or you could add an electrical thermostat to the evaporator coils to cycle the compressor.  Like the one shown below.




By the way I'd recommend leaving the A/C hooked up in the winter as it makes for great defogging.  Also the system will last longer and be happy if you run it every once in a while during the wintertime.

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