Car Air Conditioning (A/C) System – Complete Working explained.
🚗 WHAT IS CAR A/C SYSTEM?
The A/C system in a car keeps the inside air cool and comfortable. It removes heat and moisture from the air inside the car and sends cool, dry air through the vents.
It works using a special gas called refrigerant, which moves in a closed loop through pipes and different parts. This gas changes between gas and liquid form again and again to carry heat.
🔄 BASIC PRINCIPLE
“Heat always moves from a high temperature area to a low temperature area.”
The system absorbs heat from the cabin air and releases it outside the vehicle.
🌡️ A/C System Temperature Flow – Step by Step
1️⃣ Evaporator outlet to Compressor inlet: The refrigerant comes out of the evaporator as a low-pressure gas, around 5°C. It has just absorbed heat from the cabin air, so the air becomes cool, and the refrigerant becomes gas.
2️⃣ Compressor outlet: The compressor squeezes this gas, increasing its pressure and temperature. Now the refrigerant is a high-pressure, high-temperature gas, around 70–80°C.
3️⃣ Condenser outlet: The hot gas moves into the condenser, which releases heat to the outside air through metal fins. As it cools down, the gas changes into a high-pressure liquid, with a temperature of about 35–40°C.
4️⃣ Expansion valve outlet: The expansion valve suddenly reduces the pressure of this liquid refrigerant. Due to the pressure drop, the refrigerant becomes very cold and turns into a low-pressure mist, around 5°C.
5️⃣ Back to Evaporator: This cold refrigerant goes back to the evaporator, where it absorbs heat from the cabin air again. The refrigerant changes back into a low-pressure gas (around 5–10°C) and the cycle continues — keeping the cabin cool.
⚙️ AIRFLOW PATH
1.Cabin air passes through dust/pollen filter.
2.Air goes through evaporator fins → loses heat to refrigerant.
3.Cool dry air comes out from AC vents into the cabin.
4. Refrigerant continues cycle to remove heat continuously.
🧊 MOISTURE REMOVAL
While cooling, the evaporator also condenses water vapor from air. That’s why you see water dripping under the car when A/C is running — it’s normal.
A/C System Pressure and Temperature Details
The A/C system has two main sides — the low-pressure side and the high-pressure side.
1️⃣ Low-Pressure Side (Suction Side): This part includes the evaporator and the suction line going to the compressor. The refrigerant here is cool and low-pressure gas. The pressure is usually between 25 to 40 psi, and the temperature stays around 0°C to 10°C. This is where the refrigerant absorbs heat from the cabin air.
2️⃣ High-Pressure Side (Discharge Side): This part includes the compressor outlet and the condenser. Here, the refrigerant is hot and under high pressure. The pressure is usually between 150 to 250 psi, and the temperature is around 60°C to 80°C. This is where the refrigerant releases heat to the outside air.
Master Mechanic Abhishek
Car Air Conditioning (A/C) System – Complete Working explained.
🚗 WHAT IS CAR A/C SYSTEM?
The A/C system in a car keeps the inside air cool and comfortable.
It removes heat and moisture from the air inside the car and sends cool, dry air through the vents.
It works using a special gas called refrigerant, which moves in a closed loop through pipes and different parts.
This gas changes between gas and liquid form again and again to carry heat.
🔄 BASIC PRINCIPLE
“Heat always moves from a high temperature area to a low temperature area.”
The system absorbs heat from the cabin air and releases it outside the vehicle.
🌡️ A/C System Temperature Flow – Step by Step
1️⃣ Evaporator outlet to Compressor inlet:
The refrigerant comes out of the evaporator as a low-pressure gas, around 5°C.
It has just absorbed heat from the cabin air, so the air becomes cool, and the refrigerant becomes gas.
2️⃣ Compressor outlet:
The compressor squeezes this gas, increasing its pressure and temperature.
Now the refrigerant is a high-pressure, high-temperature gas, around 70–80°C.
3️⃣ Condenser outlet:
The hot gas moves into the condenser, which releases heat to the outside air through metal fins.
As it cools down, the gas changes into a high-pressure liquid, with a temperature of about 35–40°C.
4️⃣ Expansion valve outlet:
The expansion valve suddenly reduces the pressure of this liquid refrigerant.
Due to the pressure drop, the refrigerant becomes very cold and turns into a low-pressure mist, around 5°C.
5️⃣ Back to Evaporator:
This cold refrigerant goes back to the evaporator, where it absorbs heat from the cabin air again.
The refrigerant changes back into a low-pressure gas (around 5–10°C) and the cycle continues — keeping the cabin cool.
⚙️ AIRFLOW PATH
1.Cabin air passes through dust/pollen filter.
2.Air goes through evaporator fins → loses heat to refrigerant.
3.Cool dry air comes out from AC vents into the cabin.
4. Refrigerant continues cycle to remove heat continuously.
🧊 MOISTURE REMOVAL
While cooling, the evaporator also condenses water vapor from air. That’s why you see water dripping under the car when A/C is running — it’s normal.
A/C System Pressure and Temperature Details
The A/C system has two main sides — the low-pressure side and the high-pressure side.
1️⃣ Low-Pressure Side (Suction Side):
This part includes the evaporator and the suction line going to the compressor.
The refrigerant here is cool and low-pressure gas.
The pressure is usually between 25 to 40 psi, and the temperature stays around 0°C to 10°C.
This is where the refrigerant absorbs heat from the cabin air.
2️⃣ High-Pressure Side (Discharge Side):
This part includes the compressor outlet and the condenser.
Here, the refrigerant is hot and under high pressure.
The pressure is usually between 150 to 250 psi, and the temperature is around 60°C to 80°C.
This is where the refrigerant releases heat to the outside air.
🌬️ IN SIMPLE FLOW
Compressor ➜ Condenser ➜ Receiver ➜ Expansion Valve ➜ Evaporator ➜ Compressor (again)
✅ FINAL RESULT
1. Inside air becomes cool (6–10°C)
2. Moisture removed (dry air)
3. The cabin feels comfortable and fresh.
#acsystem
2 weeks ago (edited) | [YT] | 2