How to Add Refrigeration Lubricating Oil to a Compressor?
3 Answers
Compressor adding refrigeration lubricating oil methods are as follows: 1. Use the compressor's own vacuum suction to add oil. 1. Small fully enclosed compressors do not have suction and exhaust shut-off valves installed on the suction and exhaust ports. First, weld a pipe joint with a valve plug on the compressor's process pipe, then connect it to the lubricating oil barrel or refrigeration oil measuring cup through the repair valve's hose, and remove the air in the pipeline. Then start the compressor, open the repair valve to allow the lubricating oil to be sucked into the compressor. 2. Fully enclosed, semi-enclosed, and open-type compressors have suction and exhaust shut-off valves installed on the suction and exhaust ports. First, connect the oil pipe with a valve leading to the refrigeration lubricating oil barrel to the bypass port of the suction valve or the three-way valve or oil drain valve of the crankcase, while closing the compressor's suction valve and the valve on the oil filling pipe, and open the exhaust valve. Then start the compressor. When the pressure in the crankcase drops to 0Mpa, immediately close the exhaust valve. Then slowly open the valve on the oil filling pipe to suck in the lubricating oil through the oil filling pipe. 2. Use a vacuum pump to create a vacuum inside the compressor and use atmospheric pressure to push the lubricating oil in. 3. Use a gear hydraulic pump or hand hydraulic pump to directly add oil through the three-way valve or oil drain valve of the crankcase, but care should be taken not to increase the pressure in the crankcase during the oil filling process. 4. Use the compressor oil pump to add oil from the three-way valve of the oil pipe.
I frequently handle maintenance for air conditioning compressors, and adding refrigeration lubricating oil is a common procedure. First, ensure the vehicle is turned off and the key is removed. Use tools to connect to the low-pressure port of the AC system and evacuate to remove air and residual gases to prevent contamination. Use a dedicated filling gun to directly inject the refrigeration oil into the compressor. Don’t pour too much—excess oil can hinder system performance. Also, check whether the oil level is within the standard range and adjust the amount based on the vehicle model. It’s best to operate under professional guidance, as I’ve seen beginners skip the evacuation step before adding oil, resulting in reduced cooling efficiency. Regularly adding refrigeration oil can extend the compressor’s lifespan and prevent premature wear. While driving, pay attention to changes in AC noise—unusual sounds may indicate insufficient lubrication. Safety first: wear protective gloves and goggles, as refrigerant contact with the skin is harmful. If you’re unsure, it’s better to visit an auto repair shop—they have more precise equipment to get the job done.
I previously added refrigerant oil to my home car's compressor myself, purchasing small bottles of oil and simple filling tools. Choosing the correct model to avoid using the wrong oil is crucial. After turning off the engine, locate the low-pressure filling port of the air conditioning system, and slowly inject the oil using a syringe or professional injector. Don't rush, as the oil can easily leak out. I tried it twice—the first time I added too much, and the AC didn't cool properly. It only improved after adjusting to the right amount. Saving money is good, but the risks are high; if you're unfamiliar with the system's structure, mistakes are easy to make. The refrigerant oil lubricates internal parts to reduce friction—without it, the compressor can seize. I recommend checking the oil level every two years, especially during seasonal changes. Also, ensure proper ventilation before starting, and avoid working in an enclosed garage. The tools may be cheap, but if the compressor gets damaged, the repair costs will outweigh the savings. DIY can be educational, but it's best to watch tutorial videos beforehand.
