Air condition problem

[NHbalerman]

Working on the ac on my ford 7740 and when you turn on the fan switch the first notch sends fire to compressor the second and third notch the fan comes on but the compressor doesn't. I replaced the switch and it does the same thing. Did I get a bad switch?

 

[used red MN]

Working on the ac on my ford 7740 and when you turn on the fan switch the first notch sends fire to compressor the second and third notch the fan comes on but the compressor doesn't. I replaced the switch and it does the same thing. Did I get a bad switch?

Are you testing a known spade terminal on the switch that goes to the compressor? And when you select the 2nd and 3rd positions the power on that terminal drops off? More likely there are other control switches in the circuit going to the compressor, can you find those and see if they are by chance opening? If left alone long on 2nd speed does the compressor kick in again? If it does that might indicate low refrigerant. A wiring diagram of the system would be very helpful.