A problem with a car air conditioner is always tricky, both to detect it and to fix it. The first thing to do is to check that there are no leaks and that the air conditioning compressor engages correctly. If the fault is in the air conditioning circuit, there is very little chance that you can repair it yourself. On the other hand, if it is simply a question of recharging the circuit with refrigerant gas and if you are a bit of a handyman, it is within your reach: you just need to buy a recharging kit.
Part 1 of 3: Identify the problem
Step 1. Turn on the air conditioning
After starting your vehicle, turn on the air conditioning fully. Put your hand in front of one of the vents and see if the air is hot, warm, or cold. If the air comes out hot, you have an air circulation problem.
- If you don't have any air circulation, if you can't hear the blower, there is a good chance that there is an electrical problem.
- To improve air circulation, the cabin filter must also be checked or even replaced.
Step 2. Check the correct operation of the compressor
In the event of a breakdown, things must be done in order. After ruling out an electrical problem, you need to check that the compressor is working properly. Locate it in the engine compartment and check that the center of the clutch pulley rotates as the pulley rotates.
- The compressor clutch is engaged when the air conditioning is on. To check this, you should see the central part of the clutch pulley turning at the same time as the pulley.
- If the clutch is not engaged, it means either that the compressor has failed and must be replaced, or that the circuit must simply be recharged with refrigerant gas.
Step 3. Check the wiring going to the compressor
Most compressors have an electrical wire that goes to the magnetic clutch. Follow that wire and in between you'll find a switch that needs to be unplugged. Collect a piece of electrical wire and connect it to the compressor wire on one side and to the positive (“+”) terminal of the battery on the other side. If you hear a very metallic “click”, your magnetic clutch is working perfectly. If there is no noise, it must be replaced.
- Replacing the air conditioning compressor requires specific tools.
- For compressor or clutch replacement, call a professional.
Step 4. Locate a possible leak in the air conditioning system
It is not always easy to detect a leak. This is the reason why there are tracer products that are injected into the circuit through the low pressure valve. Then, either using a UV lamp or with the naked eye, it is easy to identify a leak or crack.
- The tracer product cartridge being connected to the low pressure valve, a certain quantity of product is sent into the circuit.
- If you find that there is a leak, all you have to do is hand over your car for repair.
- If you do not find any leaks, it is very likely that all you need to do is recharge with refrigerant gas.
Part 2 of 3: prepare to add refrigerant gas
Step 1. Buy the correct refrigerant gas
It's not about putting just anything in your air conditioning system. We must put a particular gas: freon. Everything will depend on the year of construction of the vehicle. If it came out of the chains after 1995, it is necessary to put freon R134a. If your vehicle is older, you must put R12 freon.
- You cannot recharge R12 freon by yourself.
- If your vehicle uses R12 freon, you must go to a professional to recharge it.
Step 2. Note the ambient temperature
Since gas pressure is related to temperature and volume, it's important to know what the temperature is when you recharge. Refrigerant gas is a liquefied gas (therefore compressed) which occupies a different volume depending on whether its temperature rises or falls, the consequence is that its pressure, in a cartridge or a circuit, varies.
- So, since you will be relying on the pressure gauge to read the pressure, it is useful to know the ambient temperature during recharging in order to properly fill the circuit.
- When a refrigerant gas expands, it takes up more space and pressure increases in the cartridge.
Step 3. Locate the low pressure valve for your circuit
On this circuit, there are actually two valves: one for low pressure and another for high pressure. For gas refill, only the low pressure valve is concerned. The error is not possible: the two valves have a different diameter.
- To locate this low pressure valve, simply follow the air conditioning pipe which is in the engine compartment, under the windshield. There you will find a sort of small branch topped with a plastic cap.
- If you do not find it, refer to the technical review of your vehicle in the chapter on air conditioning.
Step 4. Clean the area around the valve
Before removing the cap, using a clean cloth, clean the valve head, cap and all around. This way, when you plug in your fitting, you will be sure not to introduce dust into the valve and the circuit. In order, clean the pipe on both sides of the valve, the cap, then the latter being removed, the top of the valve itself.
If the hose is really dirty, you can put some brake cleaner on your rag
Step 5. Secure the fitting to the low pressure valve
A refill kit consists of a gas cartridge and a fitting that is attached on one side to the low pressure valve identified previously, and to the head of the cartridge on the other side. Before going any further, check that the fitting is correctly engaged on both sides.
- If the connection is fitted with a pressure gauge (graduated screen), which is almost always the case, the long part of the connection is first attached to the valve, while the short part is then attached to the gas cartridge..
- The fitting is long enough that you don't have to place the cartridge over the engine block just for safety.
Step 6. Take the ambient temperature into account
The compressor is operating due to the ambient temperature. This is why you must take this into account when recharging the circuit in order to reach the recommended pressure. Throughout the recharge, closely monitor the pressure gauge to stay within the standards provided by the manufacturer.
- The pressure gauge needle will tell you when the circuit is recharged, at the right pressure.
- To read the pressure gauge, refer to the small technical manual delivered with the refill kit.
Part 3 of 3: recharge the circuit with refrigerant gas
Step 1. Punch the gas canister
With the fitting in place on the gas cartridge, you must puncture the safety seal. To do this, turn the small tap clockwise until you hear a hiss which indicates that the gas is passing from the cartridge to your air conditioning circuit.
Some cartridges open differently. For further explanation, always read the operating instructions before doing anything
Step 2. Hold the cartridge vertically
While filling the circuit, be sure to keep the cartridge upright, head up, and shake it from time to time. If you hold the cartridge tilted, it is not dangerous, just the pressure will eventually drop and the filling of the circuit will be bad.
- If it is necessary to shake, it is because this gesture increases the pressure inside the cartridge and thus, you can continue to fill your circuit quietly.
- Do not hold the cartridge upside down to maintain sufficient pressure.
Step 3. Check for leaks
While recharging your circuit, monitor the pipe to see if there is a leak. If so, note the precise location. You will need to give this information to your mechanic, because it is a repair that cannot be done at home.
In general, leaks are best found when recharging the air conditioning system
Step 4. Undo the fitting
If you still have gas, store everything, fitting and cartridge in a cool place. Once the circuit has been recharged, remove the fitting from the valve and replace the cap. If the cartridge is not empty, you can use it on another vehicle or keep it for the next time.
- If the cartridge is empty, put it aside to be disposed of in a recycling center.
- If you keep a partially emptied cartridge, check it for leaks.
Step 5. Have your air conditioning system repaired
In the event of a leak on the circuit or a faulty clutch, there is little other solution than to entrust your vehicle to the good care of a professional. Replacing an air conditioning compressor requires hardware and skill, and even a good DIYer will have a hard time doing it.