There is no ac relay on the 73. However, there is a ambient air temp switch located between the radiator and grille. This switch is prone to failure. In the winter, below around 32 degrees, the switch opens. When it warms up, the switch should then close and supply current to the compressor but. The switch often fails. You can bypass it and run it that way, but the ac compressor will then run even when its below 32 degrees. There are no other switches between the main heater/ac switch and the ambient air switch, then straight on to the compressor clutch. I learned this from Bill at Lincoln Land today. He is the man! 727-446-2193 Hope this helps someone.
Monday, April 11th, 2011 AT 3:47 PM