If you've just completed an AC repair that requires adding compressor (PAG) oil to the AC system, your AC vacuum pump can be used to pull the oil in (via the AC Service Port) with no fuss or mess. I've found this to be easier, faster and cleaner than pouring oil into your new condenser or accumulator. Just attach your pump to the low pressure port, remove the schrader valve on the high pressure port, turn on the pump and let the air suction from the HP port suck in the oil via a rubber tube between the port and oil bottle.
If your ac system has been suffering from a leak, some PAG oil is lost and must be replenished. This is why many of the 12 oz freon cans come preloaded with 1 oz of oil with some type of stop-leak component. So you're basically getting 11 oz of refrigerant instead of 12. The evacuation does not pull the remaining balance of oil out of the system. When you recharge the system after replacing the component that has failed, you need to add oil to compensate for both the lost oil from the leak and the oil lost residing in the replaced component. This is all guess work. If you want a perfectly accurate amount of oil to reside in the system, then you need to have it evacuate and recharged from a professional evacuation and recharge machine. Another method is to take the compressor off (if not the source of the leak and not being replaced), measure out the amount of oil in it, then calculate the amount of oil needed to bring the amount of oil needed to bring it to the manufacturer's specs. I one time ruined a replaced compressor because I didn't add enough oil to compensate for lost oil from a replaced evaporator. The oil acts as a coolant for the compressor and lack of oil will burn out a compressor.
After the PAG oil has been added, reinstall the schrader valve and pull a vacuum on both the high and low pressure quick connect ports. Check the gauges and see if you're close to -29 psi with the pump off; if the needle slowly heads back towards zero, you have a leak somewhere. If no leaks, pull vacuum for around 15 to 30 minutes. This should remove all residual moisture in the system. Afterwards, you're ready to introduce your refrigerant.
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Parts & Specialty Tools:
Windshield Washer Hose Kit (can use between PAG bottle and service port)
Air Conditioner Leak Detector Tool Flashlight Oil & Sniffer
Automotive Heating & Air Conditioning Haynes TECHBOOK
AUTO AC Repair Complete Tool Kit with 1-Stage 3.5 CFM Vacuum Pump, Manifold Gauge Set, Hoses and its Accessories
TSI Supercool A/C Comp PAG Lube, 8 Oz, Flash Point 442 F
Valve Core Remover with 20 Pcs Schrader Valve Cores Dual Single Head Valve Core Remover Tool
41Pcs Car Air Conditioner Valve Core Schrader Valve Cores Accessories A/C R12 R134a Refrigeration Tire Valve Stem with Double Head Dual
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