1991buick riviera ac problem

[Autry]

Please help my 1991buick riviera ac compressor is new as well as new orfice tube and accumulator charged fully and new low pressure switch but ac clutch engages 5sec and shut off and wont engage again until 2mins later and shuts off in 5sec and I changed the ecm below the glovebox. I was thinking the ecm would hold the ground for ac clutch to stay engaged because when I jump the ac relay the clutch stays engaged and ac lines aren't cold as before just warm the I noticed ac pressure sensor switches on the line behind the low pressure switch line how many pressure switches does this car have I thought just low and high

 

[HotZ28]

That system has only two pressure sensors, one High on the compressor & one low on the accumulator. Did you pull a vacuum on the system before recharging? I assume you converted from R-12 to R134-A? Have you tried disconnecting the battery & reconnecting it? A lot of unknowns here!