What tool(s) are used the check the sub-cooled liquid line? High pressure gauge only High pressure gauge and a thermocouple Thermocouple only Compound pressure gauge only Compound pressure gauge and an amp probe Compound pressure gauge and a thermocouple What tool(s) are used the check the sub-cooled liquid line? High pressure gauge only High pressure gauge and a thermocouple Thermocouple only Compound pressure gauge only Compound pressure gauge and an amp probe Compound pressure gauge and a thermocouple