Why does my explorer run hot when a/c is on?

yep. After about 30 minutes of drive time, the temp starts climbing

Restricted radiator most likely.

how do I check this?

There are some test a technician can perform with equipment you do not have!... Suggest having it checked out to prevent unnecessary parts replacement !

not head gasket, have flushed radiator, again. nothing. just wondering could the fan clutch cause this when the a/c is on? doesn't run hot unless a/c is on.