I have a 1998 Dodge caravan with 144000, latley when the ac is in max cool and i am driving on the highway the low side hose freezes up and the evap freezes also so the air coming out of the vents slows down. I turn it off or open the ouside vent and it will un thaw. My limited knowlwdge stells me it is low on charge but the AC place i go to says its ok. Yesterday the compressor belt broke so i replced it and the ac worked for a while and now it will not engage the clutch. i can not find the switch to jump to try to put some freon in it. any ideas?