Have you been sweating in your car for a while because the air conditioning is broken? Here's a quick guide to how AC works, why it might stop working, and what you can do about it.
Steps
Method 1 of 2: Part 1: Understanding the car air conditioner better
Step 1. Realize that air conditioning in a car is really just a refrigerator in a different setup
It is designed to move heat from one place (the inside of the car) to another place (outside). A complete discussion of each specific model and component is beyond the scope of this article, but this article can help you figure out what the problem might be. You may be able to fix it yourself afterwards, otherwise at least you can intelligently talk to someone who will fix the air conditioner for you.
Step 2. Learn the most important parts of the air conditioner in a car:
- The compressor: this moves the (low pressure) gaseous refrigerant to the condenser (high pressure)
- The coolant: This liquid displaces the heat. On newer cars, this is usually a substance called R-134a or HFO-1234yf.
- The condenser: The heated refrigerant is pumped through the condenser. Here it gives off its heat to the wind or through a fan. Due to the drop in temperature, the agent becomes liquid.
- The expansion valve: The liquid coolant in the car from the air conditioner is still under high pressure and flows to the expansion valve. It reduces the pressure by passing a small amount of coolant, measures the flow and atomizes the coolant.
- The evaporator: in the evaporator the refrigerant becomes gaseous again. Due to the pressure reduction, it starts to boil and extracts heat from the air in the interior. The blower blows the air past the evaporator.
- The filter drier: it removes dirt and moisture from the refrigerant.
Step 3. Understand the process of air conditioning
The compressor pressurizes the coolant and sends it to the coils/fins of the condenser, which are usually located in front of the radiator.
- Compressing a gas creates heat. In the condenser, this heat and the heat picked up by the refrigerant in the evaporator is transferred to the outside air. When the coolant is cooled to saturation temperature, the gas will be converted into a liquid (condensation). The liquid then passes through the expansion valve towards the evaporator, which is the coils inside the car, where it loses the pressure that was added in the compressor. This ensures that part of the liquid is converted to a gas (low pressure) and that cools the remaining liquid. This mix enters the evaporator, the liquid part now absorbs the heat from the air and evaporates.
- The car's blower circulates air past the cold evaporator and back into the car. The coolant now goes back into the cycle and everything starts from scratch.
Method 2 of 2: Part 2: Fixing the air conditioner
Step 1. Check if you can see that there is a coolant leak (there is not enough liquid to dissipate the heat)
Leaks are easy to find, but not easy to fix without taking parts apart. At the auto supply store, you can buy a fluorescent paint that you can add to the cooling system to make it easier to find a leak. The instructions are on the bottle. If the leak is very large, there may be no pressure at all in the system. Try to find the valve on the low side and check the pressure with a PSI pressure gauge.
Don't poke the valve with anything else to see if anything comes out
Step 2. Make sure the compressor is running
- Start the car, turn on the air conditioning and look under the hood. The compressor looks a bit like a pump and has large rubber hoses going to it. It doesn't have a filler cap, but it usually has one or two valve-like protrusions on it. The pulley on the front of the compressor consists of a pulley on the outside and a hub on the inside, in the middle, which rotates when an electronic clutch is engaged.
- If the A/C is on and the blower is on, but the center of the pulley is not turning, there is something wrong with the compressor clutch. It could be a fuse, a wiring problem, an AC button in the dash that isn't working, or there's not enough coolant (most systems automatically shut off the compressor if the pressure gets too low as a safeguard).
Step 3. Look for other causes of the problem
Other causes of a non-functioning air conditioner can be: a broken V-belt (which prevents the pump from turning), blown fuse, broken wire, bad switches or a broken compressor gasket.
Step 4. Feel in the car if the air conditioning is working somewhat
If you can feel cool air, but not very much, the problem may be too low a pressure. Then adding the coolant could solve the problem. Read the instructions on the purchased coolant.
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Never add too much coolant. More coolant than the recommended amount will cause the air conditioner to malfunction. Better garages have a device that allows them to see if the cooling performance continues to improve while topping up. The moment the weather decreases, liquid is removed again, until the ideal level is found.
Pocas cosas
Tips
- If you think the problem is bad wiring, most compressors have a wire that goes to the electronic clutch. Find the connection in the middle of the wire and disconnect the compressor. Take a piece of wire, connect the wire from the compressor to the positive terminal of the battery. If you hear a loud CLICK there is nothing wrong with the clutch and you should look for the problem in the car wiring or fuse. If you don't hear anything, the clutch is broken and the compressor needs to be replaced. Ideally, you should do this test with the engine running, so you can see if the hub is spinning in the center of the pulley. This way you can test whether the clutch engages, but the pulley slips so much that no pressure is built up. Be careful not to get your fingers or any rags in between.
- The problem could also be the heat generated by the engine, which reduces the efficiency of the air conditioner. In that case, you can try to better insulate the cold air conditioning pipe.
- There is a light oil in the system.
- If there is a leak in your system while the drain pipe is still clean, it is possible that rainwater has entered the air conditioning system.
- Older cars and vintage cars use the refrigerant R12. It is possible to have this system converted to R-134a.
- According to EU agreements, the introduction of HFO-1234yf should have taken place on 1 January 2013. Before that time, car air conditioners were filled with the refrigerant R-134a as standard. However, this is an extremely potent greenhouse gas with a global warming potential (GWP) of 1,430 times that of CO2. Given the strong tendency of car air conditioners to leak, Brussels decided years ago that the use of this gas had to end.
- The car industry is questioning the use of HFO-1234y as a refrigerant, according to a study by Daimler in September 2012, the agent is a fire hazard. Volkswagen says it has now found a solution and will equip its passenger cars with air conditioning with CO2 as a refrigerant.
Warnings
- Watch out for moving parts under the hood!
- Always be careful when attempting to repair the air conditioner yourself. An expert at the garage has much more knowledge in this area, so when in doubt, always go to a garage!
- Keep sufficient distance from large coolant leaks. It can be so cold that your skin immediately freezes and that causes 'burns'.