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Discussion Starter · #1 ·
Have an A/C problem with a '78 Trans Am. New compressor, high fan blower relay, blower motor resistor and a new heater/A/C control unit.

We ONLY have high speed in the blower motor. AND when you turn the A/C on and the compressor kicks on, the Voltmeter drops to nothing and the engine wants to die.

Any ideas?
 

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Got good clean grounds? Where does your battery ground go? Got a ground from the engine to the chassis? I'd also clean the connectors on the alternator. What's the amperage on the alternator? Any monkey business with the blower wiring? I had a baked connector on my relay.
 

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There is a A/C high idle switch that should be connected to the side of the carb running from the A/C wiring. You can see the red wire running across the engine in this picture.

Motor vehicle Electrical wiring Cable Gas Auto part

Motor vehicle Electrical wiring Cable Gas Wire

I'll find a picture of the high idle switch.

Here is a pic of it.

Motor vehicle Automotive fuel system Auto part Gas Automotive air manifold
 

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Discussion Starter · #4 ·
PROBLEM SOLVED. Main issue was having ONLY Hi speed fan yet tore the dash half apart for nothing.

After testing wiring between the blower resistor and the hi blower relay, I unplugged the relay and found that the Reproduction wiring harness was put together WRONG at the plug. Red and blue wires were out of place and the blue wire was in a dead slot and went to no terminal on the relay. Corrected that and everything works now.
 
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