a/c compressor saftey switch??

[spc mike]

i have an 85 toyota 22r with a/c recently installed, but the compessor wont engage and i was wondering if there was no freon in the system if their was a saftey switch that doesnt let it kick on??

[brainlessfool]

start with the low presser switch. jump it.

[spc mike]

i replaced the low pressure switch. and i jumped the compressor @ the power wire under the hood and it engages but when i press the button in the dash  for the A/C its a no go. so its either the amplifier or its just because theirs no freon so thats why i need to know it theirs a automatic saftey switch in the compressor or something.

[brainlessfool]

there's a low switch, a high switch, and a over temp switch. maybe others dep. on the ext. systom.