Expert ReviewedHow to Recharge the Air Conditioner in a Car Do-it-to-yourself auto air conditioning recharging requires eye protection, a charging kit, refrigerant, and some practical knowledge. Keep in mind, if you do not have the manufacturer's specifications and a charging manifold with gauges, you will not be able to do a professional job, but many people successfully recharge their AC with kits available at big box stores and auto parts retailers. Try to get a kit that includes a pressure gauge, this will make troubleshooting and charging easier. Be aware that this particular process is usually best left to a professional mechanic. Determine if you have any refrigerant left in your system at all. Check for any obvious leaks. Make sure the condensing coils are not obstructed with debris, and that the compressor is operating.low charge Tap your refrigerant can. Securely thread the tapping valve on the refrigerant can, close the valve completely shut. Purge the charging hose.

Locate the low pressure charging port on the refrigerant line on your car. Crank your engine and turn the AC on high cool, high fan. If your recharging hose is equipped with a pressure gauge, check it to determine if the system needs refrigerant. If the pressure holds steady in the recommended range, the system is full and should not be charged. If the pressure is below the recommended range, follow the instructions to recharge the system. Another indicator that the system needs refrigerant is that the compressor cycles rapidly. If the compressor switches on and off every 5 to 20 seconds, it is most likely due to low pressure. You will see the pressure drop when the compressor kicks on, the compressor will shut off when the pressure gets too low, and the pressure rises back up to the operating range as the system equalizes. Compressor cycling (switching on and off) in a completely charged system should be very slow (every 30 seconds or up) or not at all present (compressor stays on) in hot weather.

Be aware if the cooling fans for the radiator are on and functioning with while the AC system is on. If the compressor is on, the cooling fans should also be on to assist in cooling the freon in the condenser, located either in front or behind the radiator. Most vehicles have 2 fans, with one being dedicated to the AC system Open the valve until you hear refrigerant passing through the hose. Allow the can to dispense its contents.Keep the can with the tap uplocal air handling unit Close the valve and disconnect the hose when the can is empty or no longer discharging enough to keep the can cold.air conditioning unit and installation Check the air from the AC vents in the car.ac air filters home This is part 1 of a 2-part video on how to charge a R134a AC system.

Click through the video to YouTube to view the second part. Later vehicles run on R134a. These systems have different size ports, making identification easy. Generally avoid a kit that contains a substance for sealing leaks. The sealant can harden in inappropriate places and cause problems; get the leak fixed properly, or, if it is a very slow leak, just leave it be. If your car is earlier than approximately 1993, the air conditioning will operate on R12 which is now obsolete. However there are replacement refrigerants such as Freeze12 which will not require you to convert your system to R134a in order to recharge. You can get an R12 to R134a conversion kit at an auto parts store, but should consider having it done professionally. A DIY air conditioner recharge can be pretty risky. You can look at your manifold gauges for the Hi and Lo sides and determine if the system is low, but it won't tell you how low the system is. You need to be fairly accurate in the amount of freon you add in order to prevent damage and for the system to work.

The only way to know how much freon is in the vehicle, is to remove it and weight it using an A/C servicing machine that recovers as well as charges. In most cases, it's best to take your car to a professional for this service. R-12 is now more expensive and can be found on eBay. Although it requires a license to buy, and to evacuate and recover a system. Getting caught doing so without a license will result in a fine and/or imprisonment. So it may be wiser to have your A/C converted to R-134A. This can easily be done with the retrofit conversion kits on the market now. Some even come with how to videos. R-12 is no longer used because it contains CFCs and is harmful to the environment if it gets out of the system. Don't mix R-12 and R-134 refrigerant. This is not illegal, but isn't efficient. R12 and R134a require different oil for lubrication. R-12 systems use a mineral oil, R-134a systems use a polyalkylene glycol (PAG) oil. A mixture of the two will displace more space than needed in the system and could result in an overfill, stressing the compressor.

If you change the compressor, it is highly recommended to also change the filter/dryer and you may have to flush the condenser. Either Ester or PAG oil can be use on a conversion. One thing to consider with PAG oil is if it is left out it will absorb humidity and water. It also can become an acid and corrode your A/C system and cause leaks. Get a recharging kit that includes a pressure gauge. Beware that once the low side reaches around 30 psi the high side can continue to increase to excessive pressure levels if not monitored — do not overcharge, fix leaks use a manifold gauge set and be safe!If your air conditioner is not cooling well because the system is low on refrigerant, recharging the system with refrigerant should restore normal operation. This can usually be done with a few cans of refrigerant and a simple service hose connection. First, wear safety glasses to protect your eyes. Also avoid skin contact with refrigerant. The chilling effect of spilled refrigerant can cause instant frostbite on bare skin or eyes!

Next, you need to figure out what type of refrigerant your vehicle requires: On 1995 and newer passenger cars and light trucks, the correct refrigerant is R134a. DO NOT use any other type of refrigerant. On most 1994 and older passenger cars and light trucks, the original refrigerantR12 is no longer available to do-it-yourselfers and is very expensive. When older vehicles with R12 A/C systems need refrigerant, they can be refilled with recycled R12 from other older cars (this requires taking your car to a repair shop for professional service), or with some alternative refrigerant other than R12, or with R134a (which requires certain modifications). CAUTION: Mixing different types of refrigerants is NOT recommended. Use the same type of refrigerant that is already in the system unless you are converting an older R12 system to R134a or another refrigerant. WARNING: Flammable refrigerants are illegal. DO NOT use any type of flammable refrigerant (propane, butane or flammable hydrocarbons).

For more information, see Flammable Refrigerants Click here for more information about retrofitting older vehicles with R12 A/C systems to R134a. Next, you need to locate the service fittings on the A/C system. There are two: a LOW side fitting and a HIGH side fitting. The LOW side fitting is usually located on the suction hose or line that goes from the accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressor to the condenser. On older R12 systems, the LOW and HIGH pressure service fittings are screw-type schrader valves. On newer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOW pressure fitting is SMALLER than the HIGH pressure fitting. 1. Connect the recharge service hose and valve to a can of refrigerant. 2. Turn the valve on the service hose to puncture the top of the can. 3. SLOWLY turn the valve back out to release a small amount of refrigerant into the hose.

This will blow air out of the hose (which you do not want in your A/C system). 4. Close the valve so no more refrigerant escapes, then quickly connect the other end of the service hose to the LOW pressure service fitting on the A/C system. DO NOT connect a can of refrigerant to the HIGH side service fitting. The operating pressure inside the A/C system when it is running may exceed the burst strength of the can, causing the can to explode! This should be impossible to do because the service hose for recharging the A/C system will only fit the smaller LOW pressure service fitting. Even so, you should be aware of the danger. 5. Hold the can UPRIGHT so no refrigerant liquid enters the service hose. You only want VAPOR to be pulled into the A/C system (the compressor may be damaged if it sucks in a big dose of liquid!). 6. You should use a gauge to monitor the recharging process. Though not absolutely necessary, a gauge will help you recharge your A/C system more accurately, and reduce the chance of undercharging or overcharging (either of which will reduce cooling performance).

A high pressure A/C gauge can be connected to the HIGH pressure service fitting, or a low pressure A/C gauge to the LOW pressure service fitting, or gauges can be attached to both fittings (that is what professional technicians do). NOTE: Some DIY recharging kits include a low pressure gauge on the service hose or on a trigger-grip style can dispenser. 7. Start the engine and turn the A/C on MAX/HIGH. 8. NOTE: The compressor may not engage if the system is too low on refrigerant. The low pressure cutout switch will prevent the compressor from running if the system is too low on refrigerant (this is done to protect the compressor from damage due to a lack of proper lubrication). The compressor must be running to suck refrigerant through the service hose into the system. So if it is not engaging when you turn the A/C on, you may have to supply battery voltage directly to the compressor clutch using a fused jumper wire. Look for a single wire connector near the front of the compressor, unplug it and hook up a jumper wire to the battery POSITIVE terminal.

This should cause the clutch to engage and the compressor to run. 9. OPEN the valve on the service hose so refrigerant vapor will flow from the can into the A/C system. It may take up to 10 minutes or more per can to suck all of the refrigerant out of the can into the A/C system. Feel the air coming out of the ducts inside the vehicle. It should be getting colder. 10. If you are using a high or low pressure gauge (or both) to monitor recharging, look at the gauge(s). When the reading is between with the A/C running, The system is fully charged and should be cooling normally. DO NOT add any more refrigerant. If the gauge is over 50 psi, you have overcharged the system with too much refrigerant. When the reading gets up around (R12), or(R134a), The system is fully charged and should be cooling normally. DO NOT add any more refrigerant. The high and low pressure readings will vary depending on the system and ambient temperatures (higher temperatures cause higher system pressure readings).

Most newer passenger car A/C systems do not hold much refrigerant (only 14 to 28 oz.), so you don't want to add too much if the system is low. One can of R134a typically holds 12 oz. of refrigerant. 11. If the system needs more refrigerant after adding one can, you can add a second can. CLOSE the valve on the service hose, then disconnect the hose from the empty can, screw a new can onto the service hose valve, turn the valve to puncture the new can, then turn the valve all the way back out again so refrigerant can flow through the hose into the A/C system. When you have finished, turn the engine off. CLOSE the valve on the can of refrigerant before disconnecting the service hose from the LOW pressure fitting (in case there is any refrigerant left in the can). Don't vent any left over refrigerant from the can. Leave the service hose attached to the can with the valve closed so you can save the refrigerant for a future recharge. Remember to replace the plastic caps over the service fittings, and remove the jumper wire from the compressor if you had to jump it to make it run.