Mid (Test) Position
After installing manifold gauge set (valve stem in back-seated position), turn valve stem 1 1/2 - 2 turns inward. This positions valve stem midway, allowing full system operation and permitting refrigerant pressure to reach gauges.
Front-Seated (Off) Position
With service valve stem turned inward, valve blocks refrigerant flow through system, isolating compressor for service.
| CAUTION | NEVER operate A/C system with service valves in front-seated position, as the compressor will be damaged. |
PURGING TEST HOSES
- Ensure high-side and low-side hoses are properly connected to service valves, and all hose connections are tight.
- If stem-type service valves are used, turn stems inward 1 1/2 - 2 turns to mid-position. On all applications, place clean shop towel over end of center service hose.
- Purge high-side test hose by opening hand valve on high-side gauge for 3-5 seconds. This allows system's refrigerant to force air through test hoses and out of center service hose into the shop towel. Immediately close high-side gauge hand valve.
- Purge low-side test hose in the same manner using hand valve of low-side gauge. Close hand valve after 3-5 seconds. Purging of test hoses is now complete, and system is ready for testing.
LEAK TESTING
Operate system to stabilize high-side and low-side pressures. Turn engine off. Using a refrigerant leak detector, check all refrigerant line connections for leaks. Check compressor seal area and condenser.
Refrigerants are heavier than air. Always check for leaks at bottom of refrigerant lines and components. Refrigerant oil will leak with refrigerant. Visually check all connections and compressor clutch area for oil stains. If compressor shaft seal is leaking, a fresh oil streak will normally be seen on underside of hood, above compressor clutch.
Always perform leak testing after A/C service. Move refrigerant leak detector slowly to check for leaks, as leaks will not be detected if leak testing is performed too quickly.