AC low pressure valve

[hionlyf]

Can someone tell me where the AC low pressure valve is on my 1973 Dodge Polara Custom. Its 360, 5.9L. Thanx.:70s_rule:

 

[70bigblockdodge]

Valve or switch, switch is on the drier/accumulator, valve is not low pressure but evap regulator pressure ,erp its inside where low side/suction comes into compressor in rear top facing air cleaner.