Chevrolet Repair: 1992 k3500 a/c, hi psi, crate motor

Question
hi, i just put a crate motor in my 92 k3500. i also put new a/c comp. and recharged system. when i turn on a/c or heater the comp. keeps coming on and off. it blows hot air when on heater but a/c still continues to cycle on and off. thank you for any help.

Answer
You are going to need to install psi gauges on the ac system and see what the psi is.  There are 2 reasons why it will cycle like that.  The first is the freon charge is not correct (not enough freon)  The second is that you have a restriction causing the pressure to build way to high way too fast.  This will cause the hi psi switch to kick out.