2004 Corolla A/C problem

After searching for a little while I believe there are not many Toyota’s with a/c problems. I am trying to help a friend out with his wife’s 2004 corolla. The a/c is not cooling everything seems fine. The a/c switch inside engages the cooling fan. The motor rpms rise. But the compressor does not kick on. Plenty of 134a in the lines, a test of the 12v lead to the clutch shows no 12v. The a/c fuse is good… Is there a relay? If I put 12v to the clutch it engages and cools… I suspect the switch on the line is bad. Anyone know how to test the high pressure line switch? It has 4 wires????
What is the next step back from the compressor to test? I would appreciate any help you guys can give; I think we are going to try to work on it again this weekend… If anyone can help please do my buddies wife is pregnant with no a/c!!! I am sure he will get an ear full every night when she comes home till it is fixed!!!!
B.T.W. For you guys up north, yes we need a/c this time of the year in south Louisiana!!!!

The relay was bad it was labled mc, mac or something like that. It is in the pannel under the hood on the drivers side.

there is a tsb for this issue, it will be covered under 3yr,36k warranty if its still applicable.

every car from i think 2000 on has this crap relays. we cant keep em in stock. should be a recall imo.