How to Add Oil to an AC Compressorby Don Bowman
Adding oil to an air conditioning compressor must be done with the air conditioning system evacuated by a recovery machine, since it is illegal to release refrigerant into the atmosphere. To be done correctly, every air conditioning system has a specific amount of refrigerant oil determined by the length of hoses for the system. The refrigerant oil is suspended in the Freon and too much oil will clog the components and be detrimental to its operation. If a leak in the system has been located and repaired, such as a loose fitting, a small amount of oil can be introduced into the system with the engine running without harm to the unit.
Hook the reclaimer to the high and low side valves on the air conditioning unit. The high side is the small diameter line and the low side is the large diameter line. Turn the machine power on and open the charging tank.
Open both the red (high side and the blue (low side) valves on the front of the reclaimer. Push the button that says "reclaim." Let it run in this mode until both gauges read "0." Turn the valves off to both high and low side valves and make sure that the gauges read "0."
Remove the high and low lines from the air conditioning unit on the engine. Remove the electrical connector from the air conditioning compressor. Remove the air conditioning drive belt. Remove the air conditioning manifold lines attached to the air compressor. Remove the air conditioning compressor.
Empty the air conditioning compressor of all the oil by holding the open end down while rotating the clutch by hand in the normal direction of rotation. Retrieve the correct amount of oil information from the AC sticker on the car or from a maintenance manual. The next steps must be done in a near sterile fashion. In other words, do not get any foreign sediment in the compressor or it will harm the operation of the system.
Pour the oil very slowly into the intake port or low side of the compressor. This is where the large line entered. While pouring in the refrigerant oil, rotate the hub and clutch slowly to let the oil enter the compressor. If the compressor takes 6 oz. of oil per the instructions, use all 6 oz., but be sure it is nothing but refrigerant oil, as nothing else will work. Once that is completed, lay the compressor down on the hub for 10 minutes to let the oil seep into and lubricate the front seals to prevent leaks on startup.
Install the compressor and spin the hub ten times by hand and install the drive belt. Make sure that the manifold that attaches the lines to the back of the compressor has good o-rings that are totally clean. Attach the manifold and tighten the bolt.
Install the electrical connector on the compressor and reattach the high and low side hoses from the reclaimer. Open both valves on the reclaimer and hit the button for "vacuum." When the reclaimer asks how long, enter "30 minutes" and hit the "start" button.
Close both of the valves after the vacuum pump shuts off and watch the gauges to see if there is a leak. The gauges should be showing about 30 inches of mercury. If the gauges drop, there is a leak. Open the valves on the low and high side and hit the button for "charge." Look at the car's AC tag--all cars have a tag stating how much Freon the unit holds--and punch in the amount in the window of the reclaimer. Now hit the "charge" button and let it charge the lines. When the panel says that the charge is complete, shut both valves off on the reclaimer and remove the lines from the air conditioning unit, then install the caps on the valves.
Things You'll Need
- Set of 3/8-inch set of sockets
- 3/8-inch ratchet
- Set of wrenches
- Air conditioning reclaimer with gauges
- Make sure you have the correct type of refrigerant oil for the car. It will say what type of oil is used on the sticker (i.e. R134).
Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).