2001 Pontiac Montana Pressure Readings

I have hooked up a/c guages to lo and hi connections and I get a correct static pressure on both with car off ( mid 70's psi @ 80 ish degrees F ).
When car started and running for about a minute I press a/c button and here the ac kick in but only get hot air. The guages read lo - 32psi and hi - 100psi. All the a/c troubleshooting tips I have read has no information for these readings. They have lo lo - hi lo
lo high - hi high etc. With possible causes. I assume the compressor is kicked in because the lo and hi pressure guages change when the a/c button is depressed. Any help would be appreciated

Bob G.