How to Read the Pressure on an Automotive Air Conditioning Pressure Gauge
2 Answers
An automotive air conditioning gauge typically has two dials, one blue and one red. The blue dial indicates low pressure, while the red dial shows high pressure. Under normal operating conditions of the air conditioning system, the low pressure should range between 1.0–2.5 bar, and the high pressure between 15–18 bar. If the low pressure exceeds or falls below this range, it indicates abnormal expansion valve regulation or potential issues with the compressor's performance. Below are detailed explanations about automotive air conditioning: 1. Definition: The automotive air conditioning system, abbreviated as car AC, is designed to regulate and control the temperature, humidity, air cleanliness, and airflow inside the vehicle cabin to optimal conditions. It provides a comfortable environment for passengers, reducing travel fatigue, and creates favorable working conditions for the driver, playing a crucial role in ensuring safe driving. Generally, it includes refrigeration, heating, and ventilation systems. This integrated setup maximizes the limited interior space of the vehicle, featuring a simple structure and ease of operation, making it a globally popular modern automotive air conditioning system. 2. Components: Modern air conditioning systems consist of a refrigeration system, heating system, ventilation and air purification devices, and a control system.
When I check the car's AC pressure, I first start the engine, turn on the AC to maximum cooling with the fan on high, and wait five minutes for the system to stabilize. Then, I connect the blue hose of the pressure gauge to the low-pressure port (marked L) and the red hose to the high-pressure port (marked H). The low-pressure gauge should read between 25-45 psi, and the high-pressure gauge between 150-250 psi is reasonable. On hot days, the pressure may be slightly higher, but as long as it doesn't exceed 280 psi, there's no major issue. If the pressure is too low, it might indicate insufficient refrigerant or a blockage; if it's too high, it could be a condenser cooling problem. Remember not to touch the moving belts while checking the gauges—once my glove got caught and it was a close call. Wait for the needle to stabilize before recording the reading, as it fluctuates and isn't accurate right after startup.
