Charging your car air conditioner yourself requires eye protection, a charging kit, coolant, and some practical knowledge. Remember that if you don't have the factory specs and a refill manifold with gauges you won't be able to do a professional job, but many people manage to recharge the air conditioner using kits available at auto parts stores. Try to get a kit that includes a pressure gauge, it will make it easier to understand the problem and reload. Here is a guide to learn how.
Steps
Step 1. Find out if there is any refrigerant left inside the system
To do this, you will need to mount a inlet hose to the low pressure manifold (more on this later). Use eye protection. If the system is completely drained it could be contaminated with moisture and refilling will not give satisfactory results unless the cause of the leak is found, repaired and the filter drier replaced. The open system must be repaired and purged using a vacuum pump to remove air and moisture. If the system has leaked, you will need to add compressor oil as well. A leak test and measurement of the oil left in the replaced compressor will tell you how much you need to put.
Step 2. Check for any leaks
If the system has lost enough refrigerant to stop working, then there is a leak. Smaller leaks can take months to run out of refrigerant to keep the air conditioner from cooling, but recharging a system that has significant leaks is just a waste of time. Look for refrigerant oil residues in the pipes, parts and fittings that make up the system. Spray a solution of soap and water on the fittings, if bubbles appear then it is a sign that there is a leak.
Step 3. Make sure the condenser coils are not blocked by debris and that the compressor is running
To test a compressor with a low charge you may need to pass the pressure switch which is often found on the accumulator.
Step 4. Score the can of coolant
It is done by fully opening the valve which thus retracts the incision pin into the valve body. If you don't, you will score the can upon installation resulting in freeing the coolant before sealing the fitting.
Step 5. Screw the valve tightly to the can of refrigerant, close the valve completely
This pushes the pin at the top of the can to allow the refrigerant to escape once the valve is opened.
Step 6. Purge the inlet hose by opening the valve until you feel it fill with refrigerant and then slowly loosen the brass fitting that joins the hose to the valve
Be careful not to let it come into contact with your skin. Squeeze the hose again once you hear the coolant leaking, it should have forced the air and moisture out of the hose.
Step 7. Find the low pressure charge point in the car's coolant duct
It is usually in a larger tube, near or on top of the accumulator. Connect the quick coupler and make sure there are no leaks.
Step 8. Run the engine and air conditioner at idle and full power
If the charging hose has a pressure gauge check it to see if the system needs refrigerant. If the pressure remains constant in the recommended range, the system is full and does not need to be charged. If the pressure is lower than recommended, follow the instructions to recharge the system. Another element it indicates is when the compressor cycles rapidly. If it goes on and off every 5-20 seconds this is probably due to low blood pressure. The pressure will drop when the compressor starts, and when it gets too low the compressor will shut down; it will then rise again to operational level when the system is back in balance. The compressor cycles (on and off) in a fully charged system should be very slow (every 30 seconds) or completely absent (the compressor stays on) in hot weather.
Step 9. Open the valve until you hear refrigerant pass through the pipe
Step 10. Let the contents of the can come out
It usually takes 2 to 5 minutes. The warmer the outside temperature, the faster they will be poured. Keep the can facing up all the time to allow non-liquid refrigerant to end up in the suction part of the system to avoid damage to the compressor. Don't overload! Use the pressure gauge to measure the high and low pressure. Consult a pressure temperature chart.
Step 11. Close the valve and disconnect the hose once the can is empty or no longer drains product to keep it cold
Check for leaks and replace the plastic cap.
Step 12. Check the air from the car fans
It should be cold, if it isn't then either a can of coolant isn't enough or there's another problem. Don't overload! Use the pressure gauge to measure high and low blood pressure. Consult a pressure temperature chart.
Advice
- Newer vehicles use R134a gas (freon). These systems have different sized entrances which make identification easier.
- If the car is older than 1993, the system uses R12 gas (freon-12) which is obsolete. However, there are replacement refrigerants such as Freeze12 which do not require you to convert the system to R134a for recharging.
- You can find an R12 to R134a conversion kit at a parts store, but it's best to have it done by a professional.
- In general, avoid a kit that has a substance to seal leaks. The sealant can harden in inappropriate places and cause problems. Adjust the loss properly or, if it is mild, leave it.
- Get a kit that has a pressure gauge. Be aware that when the idle reaches 30 psi the peak can continue to rise to an excessive pressure level if not monitored - do not overload, adjust the leaks with a pressure gauge and take no chances!
Warnings
- R-12 gas is now very expensive and can be found on eBay. However, it requires a license, including for disposal and recovery. Doing so without a license can have legal consequences. So it may be less expensive to convert the air conditioner to R-134A. This can be done with the conversion kits on the market, some even have explanatory videos.
- Do not mix R-12 and R-134 refrigerants. It is not illegal, but it is not efficient. R12 and R134a require different lubricants. R-12 systems use mineral oil, R-134a systems use PAG lubricants. A mixture of the two will take up more space in the system than necessary by overfilling it resulting in compressor strain. If you change compressor it is highly recommended to also change the filter / dryer and wash the condenser. Ester or PAG lubricants can be used in the conversion.
- R-12 is no longer used as it contains chlorofluorocarbons (CFCs) and is dangerous for the environment if it escapes from the system.
- When the idle reaches 30 psi the peak can continue to rise to an excessive pressure level if not monitored - don't overload, adjust leaks with a pressure gauge and take no chances!
