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AC Electrical


GoldAvantiII
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Hello. I'm new to this Forum as I recently purchased my first Avanti. RQB-1659 has been expertly maintained for the past 31 years by Randy Atkin. The car is near perfect. Now I get to have all of the fun of doing my best to keep it that way.

The only issue with the car is the AC not working. I took it to a friend to have the system checked out. He evacuated, oiled & recharged the system. But, no AC Comprsr clutch engagement. We ran 12v to the clutch and checked out the system and it produced ice cold air into the car .... good deal! But, no power to the wire to the AC Comprsr clutch.

I opened up the center stack. The On-Off Fan switch works as it should. The Temp switch (P/N 1552650) is wired correctly as I see it. Not sure where to go next. Any help on this would be much appreciated.

Thanks, Harv

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I cannot claim any familiarity with the a/c system, never worked on it, but...

in looking at the electrical diagram, it shows a blower switch and a temperature (thermal) switch... let's call it the t/t switch

The blower switch has a yellow wire, a black wire, and a green wire connected to it; the t/t switch is connected to the blower switch (a/c console fan) by the green wire, and it in turn connects to the compressor clutch (and to a throttle solenoid in 1977 & later models) via a brown wire.

From the diagram I assume the blower switch has to be on before the t/t switch gets power.

Therefore, with the blower switch on, it should be easy to check to see if the green wire to the t/t switch is getting 12v. If it is, the setting of the t/t switch probably determines how frequently the compressor clutch is activated (the t/t is probably a variable resistor switch that opens and closes the circuit when heated by 12v power). If you set the t/t switch to a high a/c setting and you never see 12v at the connection of the brown wire to the t/t switch (using a multimeter or test light to jumper to ground), then I'd suspect the t/t switch is bad. The other possibility is that the brown wire from the t/t switch to the a/c compressor clutch is broken somewhere in its path... to check that, just jumper the green and brown wire connectors at the t/t switch... the a/c compressor clutch should activate.

Edited by WayneC
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Wayne,

Thanks for your reply. I took your ideas and checked out the wiring attachments. I found that the 12v power wire to the fan control was attached to the lug for the fan power wire. Once I swapped these wires the system worked exactly as it should. Who ever previously swapped these must have done so in order to use the fan/blower for air flow without engaging the AC Comprsr on the low serviced system. Thanks again for all of your help on this. I now have a Cool Avanti II ..............

Regards, Harvey

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