My caterpillar 2007 262c Skidsteer ac compressor squealing on start up and sometimes for couple minutes then stops. Checked belt very tight, I can turn compressor by hand, but when turn on ac switch it sequels and compressor not engaging compressor clutch. Soon as I turn off switch it stops squealing. Even though clutch not turning compressor. Also sometimes even if ac is off is sequels for little while on startup cold or warm. Everything else works fine (condenser fans) when ac is turned on. Any help appreciated, I'm stumped. Thanks Rob