Have you ever wondered how your car’s interior maintains the desired temperature? For example, what if the outside temperature is 30° while its interior is 23°? Do you know that your car’s air-conditioner (AC) is located in the engine compartment – where the temperature can easily reach over 100°C?

So how’s the car maintaining the temperature? And, how come the AC compartment isn’t bursting into flames? That’s the beauty of your car’s AC engineering. And in this blog post, we’ll take a look at how your car’s air-conditioning works. We believe that once you get a hold of that, you can also understand how to recharge your car’s AC.

How Does a Car AC Work? 

We all know that the evaporation of liquid leads to cooling. The same principle applies to an AC as well. A car’s AC is made up of the following components:

  • Compressor
  • Condenser
  • Expansion valve
  • Evaporator
  • Propellent

The compressor is a pump that compresses the gas to liquefy it before sending it through the expansion valve to the evaporator. The gas evaporates as it goes through the expansion valve. This is the point at which the gas cools down.

A belt is one of the key components that power the compressor of a car’s air conditioner. When you switch on the air conditioner, an electronic clutch in the compressor’s pulley gets activated and drives the pump. The heat from the air in the passenger compartment is absorbed in the evaporator, and the gas flows back to the compressor through the condenser. The gas is cooled by the condenser, then liquefied by the compressor, and the process continues.

Now that we’ve covered enough mechanics, let’s look at when and how to recharge your vehicle’s AC.

Signs that indicate your AC needs recharging

To know when your AC needs recharging and is low on gas, you need to check on the following signs.

1. The AC Does Not Cool The Car 

It’s the most obvious sign! Your car’s AC is clearly not operating correctly if it doesn’t perform its basic task – which is to cool down the vehicle. The AC needs to be recharged if you aren’t receiving much cooling even at the lowest temperature.

One of the reasons for low cooling can be a clogged cabin air filter. It’s a good idea to check the cabin filter before proceeding to charge the AC.

2. The AC Clutch Does Not Engage 

The AC clutch we discussed before has a built-in safety feature. The clutch fails to operate if the refrigerant pressure in the AC pipes falls below the safe level. This happens because using the AC with a low refrigerant pressure might kill the compressor.

To check this level of auto electrical repairs you need to turn on the AC and if you notice a change in the sound of the engine and hear a click sound then it means that the clutch is working. Otherwise, the clutch isn’t working and it’s time to recharge your air-conditioner.

A faulty refrigerant pressure sensor can cause the clutch to fail to engage. Find the sensor on the refrigerant line to check for this. Remove the wires and complete the circuit. It is not necessary to recharge the air conditioner after it begins to cool.

However, if the AC still does not cool after this, do not run it for more than a minute since the compressor might be damaged if it is operated without gas.

3. Signs of Leakage 

If you find oil or grease leaking from the compressor housing or the coolant pipe joints, there’s a leak somewhere in the AC system, and the coolant has to be refilled.

Fix the Leak Before you Recharge the AC

Since leakage is the most common reason behind a loss of pressure in the AC system, you must repair the leak before recharging the AC. Here’s how you can detect a leak.

Things Needed

  • AC leak detection kit
  • UV light

The AC leak detection kit comes with a gas and a UV dye attached to it. Here’s how to use it to check for leaks. 

  • Find the low-pressure refrigerant pipe and connect it to the UV dye gas container.
  • Start the car and turn on the air – conditioning system.
  • To transmit some of the dye to the AC system, pull the trigger on the container.
  • Place the automobile in a dark area and beam the UV light over all of the AC system’s components and pipes.
  • The leak is indicated by anything that glows in the dark.
  • Before recharging the AC, make sure any such parts are repaired or replaced.

How To Charge Your Car Air Conditioner 

It’s time to learn how to charge a car’s AC refrigerant now that you know how to detect when your car’s AC system needs to be recharged. The methods are simple, but you must use precaution since you are dealing with a toxic substance, refrigerant.

Things Required for Charging Car AC Refrigerant 

Make sure you have the following items before you recharge the refrigerant in your car’s air-conditioning.

  • An AC dispenser with trigger and low side gauge
  • A thermometer
  • Refrigerant best suited to your car’s AC system
  • Safety gloves
  • Goggles

Step 1: Find Out if the Compressor Clutch is Engaging

The first stage in car freon (refrigerant) recharge is to evaluate whether or not the air conditioner compressor is actually turning. Turn on the air conditioner to see if the compressor pulley is turning or not. If the AC compressor is not working, then:

  • It might be so because of very low refrigerant pressure in the AC system.
  • The electrical system that activates the AC clutch might have failed.
  • The compressor itself might have some issue/damage.

If this is the case, we recommend that you do not attempt this as a DIY repair and instead hire a professional mechanic

Step 2: Check the Refrigerant Pressure in the AC System of Your Car 

Next, check the refrigerant pressure in your car’s AC system to ensure that the lack of cooling is not happening because of a drop in gas pressure. Here’s how you can do it:

  • In the engine compartment, look for a grey or black plastic cover attached to an aluminium pipe.
  • If you can’t locate it, look for the cap on the large coolant line that runs from the passenger compartment into the engine area.
  • To check the pressure, remove the cap and connect the pressure gauge to the service port underneath it.
  • Make that the AC compressor clutch is engaged when the air conditioner is switched on and the lowest temperature setting is selected.
  • The refrigerant pressure in the system must be at least 35 psi. Anything below that means your air conditioner has to be recharged.

Step 3: Attach the Refrigerant Can 

Connect the refrigerant can to the port on the service hose while the air conditioner is still running. Let the compressor turn while the engine is running.

  • Allow 10 to 20 seconds for the gas to enter the system after pressing the trigger on the refrigerant container.
  • Continue monitoring pressure to avoid overcharging the system.
  • Make sure that the charge doesn’t exceed 45 psi.

Step 4: Monitor the Temperature

Once the refrigerant pressure has been maintained, check to see if the air conditioner is working properly. Leave the air conditioner on and go inside.

  • Make sure the air coming out of the AC vents is at a comfortable temperature.
  • If the air conditioner is working properly, the temperature should be about 28 degrees.

Important Note 

Auto electrical repairing is a complex piece of equipment, especially the AC system. The tiniest mistake while recharging the air conditioner might cause irreplaceable damage. The refrigerant used in air conditioning systems is also extremely hazardous to the atmosphere. Don’t take the risk if you’ve never done this before. 

Unless you are sure of what you’re doing, please leave your car’s air-conditioning repairs and recharge to the professionals. For any assistance with auto electrical repairs in Christchurch, get in touch with MotorWorks Christchurch.