How to Add Oil to A/C Compressor
An oil injector adds compressor oil and leak dye through the low-pressure port, so a compressor low on oil can be topped up without a shop visit.
On this page
The air conditioning blows warm on a hot afternoon, and the compressor is low on oil. How to add oil to a/c compressor systems: use an oil injector on the low-pressure side, with the oil type and amount your vehicle manual states. The injector moves oil and leak dye into the system through the low side port, and the 4 injectors below cover that job for car and home AC work.
As an Amazon Associate I earn from qualifying purchases. GarageToolHQ earns a commission when you buy through links on our product pages, at no extra cost to you. Read our affiliate disclosure.
Below: how the injector works, the couplers and hose limits to check, and the kits that cover the job.
Aupoko AC Oil and Dye Injector with Snap Quick
A 2 oz hand-turn screw-in injector with an aluminum alloy body, brass connector and high-pressure hose, with a 13mm low-pressure quick coupler and 1/4 SAE connector for R410A, R134A, R22 and R12 systems.
Pros
- 2 oz capacity, the largest here
- Aluminum alloy body with brass connector
- 1-year warranty stated
- Fits R410A, R134A, R22 and R12 systems
Cons
- No hose pressure figure stated
- No safety certification stated
- May need a CV23p adapter on some 5/16 in R410a systems
- Setup needs more steps than the push-in kits
E-VelionX Oil and Dye Injectors Kit 30ml/1 Oz Hand
A 30ml hand-push oil and dye injector with a 13mm low-pressure quick coupler and 1/4 SAE connector, in ABS, copper and rubber, with a 1-year manufacturer warranty.
Pros
- 30ml push-in type, 1 oz stated
- 1-year manufacturer warranty stated
- 13mm quick coupler and 1/4 SAE connector
- Hose rated 355-425Psi (24-29Bar) at most
Cons
- No safety certification stated
- 30ml only, smaller than the 2 oz injector
- Listing copy matches the other 30ml kits word for word
- Fluid pipe length is approximate at about 20cm
X AUTOHAUX Oil and Dye Injectors Kit 30ml/1 Oz
A 30ml hand-push oil and dye injector with a 13mm low-pressure quick coupler and 1/4 SAE connector, in ABS, copper and rubber, for car and home AC systems.
Pros
- 30ml push-in type, 1 oz stated
- 13mm quick coupler and 1/4 SAE connector
- Hose rated 355-425Psi (24-29Bar) at most
- Suits POE or mineral oil and all refrigerant types
Cons
- No warranty term stated
- No safety certification stated
- 30ml only, smaller than the 2 oz injector
- Fluid pipe length is approximate at about 20cm
Oil and Dye Injectors Kit 30ml Manual Hand Push AC
A 30ml hand-push oil and dye injector with a 13mm low-pressure quick coupler and 1/4 SAE connector, in ABS, rubber and copper, with a 19cm fluid pipe.
Pros
- 30ml push-in type, 1 oz stated
- 13mm quick coupler and 1/4 SAE connector
- Hose rated 355-425Psi (24-29Bar) at most
- Suits POE or mineral oil and all refrigerant types
Cons
- Warranty field holds an adapter note, not a warranty term
- No safety certification stated
- 30ml only, smaller than the 2 oz injector
- Fluid pipe 19cm, shorter than the 20cm pipes here
How to add oil to a/c compressor systems
An oil injector is a small cylinder with a coupler on one end and a hose on the other. It loads with compressor oil and fluorescent dye, connects to the low-pressure side of the AC system, and moves the oil in by hand. The kits here use a 13mm low-pressure quick coupler that snaps into the 13mm female connector of a manifold, plus a 1/4 SAE connector for the system port, with the lower side preferred.
Oil type matters more than the tool. All four suit POE or mineral oil: the 30ml kits suit all refrigerant types, and the Aupoko works on R410A, R134A, R22 and R12 systems. The fluorescent dye travels with the oil to show leaks. The amount comes from the vehicle manual, not from the injector: the 30ml kits hold 30ml, and the Aupoko holds 2 oz. Check the manual for the type and amount before adding anything.
| Injector | Capacity | Coupler | Hose limit |
|---|---|---|---|
| X AUTOHAUX Injector | 30ml | 13mm, 1/4 SAE | 355-425Psi max |
| E-VelionX Injector Kit | 30ml | 13mm, 1/4 SAE | 355-425Psi max |
| KiJoeErica Injector | 30ml | 13mm, 1/4 SAE | 355-425Psi max |
| Aupoko 2 oz Injector | 2 oz | 13mm, 1/4 SAE | Not stated |
The hose pressure figure sets the limit. The flexible hose on the 30ml kits is rated 355-425Psi (24-29Bar) at most, and within 285Psi (20Bar) in normal use. The Aupoko lists a high-pressure hose with no Psi figure stated, so check its manual before use.
How to use an oil injector
- Check the manual. Find the oil type and amount in the vehicle manual before adding anything. The kits suit POE or mineral oil, but the amount comes from the manual, not the injector.
- Connect to the low side. Snap the 13mm low-pressure quick coupler onto the manifold or the low side port, and connect the 1/4 SAE connector to the system port. The listings say the lower side is preferred.
- Load the injector. Fill the cylinder with the oil and dye. The 30ml kits hold 30ml, and the Aupoko holds 2 oz.
- Move the oil in. Push the hand-push injector, or turn the Aupoko screw-in injector, to move the oil into the system. The makers say one shot may help a compressor that is low on oil.
- Watch for leaks. The fluorescent dye travels with the oil and shows where the system leaks, so check the joints after the system runs.
- Respect the hose limit. The 30ml kits list the hose at 355-425Psi (24-29Bar) at most, and within 285Psi (20Bar) in normal use. Do not push past the limit.
Adding oil means opening the AC system. If the system has lost refrigerant, or the manual calls for a recovery machine, leave the job to a shop with the right equipment. Never vent refrigerant to the air.
Use rated jack stands on solid ground, wear eye protection with power and air tools, keep fuel-burning equipment out of a closed garage, and follow the manual for every tool. Read our Safety Disclaimer.
Oil injectors for the job
Each injector below handles one part of the job: the cylinder holds the oil, the coupler joins the low side port, and the hose carries the oil into the system. The cards carry the scores and the details.
These are scored on the Shop Score, which weighs performance, build, value, safety where it applies, and warranty. No safety listing is stated for any injector here, so no injector earns safety points.
What to check before you buy
- Check the capacity. The 30ml kits hold 30ml, and the Aupoko holds 2 oz, with a range of 1/4 oz/7.5ml to 2oz/60ml stated in its listing.
- Check the coupler. Every kit here uses a 13mm low-pressure quick coupler and a 1/4 SAE connector, so the fit is the same across the kits.
- Check the hose. The 30ml kits state a hose limit of 355-425Psi (24-29Bar) at most, within 285Psi (20Bar) in use. The Aupoko states a high-pressure hose with no Psi figure stated.
- Check the warranty. E-VelionX states a 1-year manufacturer warranty and Aupoko states a 1-year warranty. The other kits state no term.
FAQ: garage tools
Can I add oil to my AC compressor myself?
Yes, with the right injector and the manual’s oil type and amount. The injector connects to the low side port and moves the oil in by hand. If the system has lost refrigerant, or the manual calls for a recovery machine, leave the job to a shop.
Which oil type do these injectors suit?
POE or mineral oil. The 30ml kits suit all refrigerant types, and the Aupoko works on R410A, R134A, R22 and R12 systems. The amount and type still come from the vehicle manual, so check it before adding anything.
How much oil does a 30ml injector hold?
30ml, which the listings also state as 1 oz. The Aupoko holds 2 oz, with a range of 1/4 oz/7.5ml to 2oz/60ml in its listing.
What is the dye for?
The fluorescent dye helps monitor leaks. It travels with the oil through the system and shows where the system leaks, so check the joints after the system runs.
Do I need a manifold to use one?
The 13mm coupler snaps into the 13mm female connector of a manifold, per the listings, and the 1/4 SAE connector joins the system port. Check the port size on your system first, and use an adapter if it differs.
Related: the AC manifold gauge vs recharge kit guide, AC refrigerant charge hoses, recharge kit vs recovery machine and the engine and shop equipment hub.
