Auto air conditioning systems are complex and have many different ways to fail. Repairing your A/C system is a multistep diagnostic process that requires skill and expertise. Kent Auto Repair is one of the first auto shops to service the new HFO-1234yf A/C systems found on late-model vehicles. Dupont HFO-1234yf is a new, more environmentally, sustainable refrigerant for automobiles with lower Global Warming Potential (GWP).

Auto Air Conditioning Diagnosis Simplified

How much will it cost to fix my car air conditioner? To answer that question, we have to diagnose the problem, starting with a pressure check.

Auto air conditioning system schematic first, check the system for proper pressure. Hook-up a machine with pressure gauges to the low and high-side ports of the auto A/C system. The most common cause of A/C failure is a low refrigerant charge. Nearly all vehicles have a switch or sensor that prevents the A/C compressor from engaging when the system pressure drops below 20 PSI.

When there is adequate pressure, the A/C compressor engages and creates a pressure difference, allowing recovery of the remaining refrigerant. Next, weigh-in a full charge of refrigerant, per the automaker’s specification. The machine has an accurate scale to measure the correct amount of refrigerant. Because it is normal for a vehicle 5 years old or more to be low on refrigerant, this would be routine maintenance. If the recharged A/C system were to perform normally, nothing further would need to be done.

On vehicles with very low or empty refrigerant levels, check for leaks by injecting an ultraviolet dye into the A/C system. Run the system, and look for leaks using a black (ultraviolet) light in a darkened area. The dye fluoresces when illuminated by the black light, causing leaks to appear brightly-colored. Be aware that small leaks could take days or even weeks to appear.

On vehicles where the A/C compressor does not engage and there is sufficient refrigerant pressure, check the compressor clutch gap, electrical switches, relays, fuses, and sensors. The compressor clutch is an electromagnetic device. When the gap is excessive, the magnetic coil is unable to attract the clutch hub, much like a magnet cannot attract a paper clip from too great a distance.

On many modern vehicles, the A/C compressor is computer controlled. There are a number of switches and sensors that can signal the computer to disengage the A/C relay. They include pressure sensors, temperature sensors, RPM sensors, sun load sensors and a wide-open throttle cut out. Climate control systems are very complex. They require knowledge, wiring diagrams and flow charts to repair.

Manifold gauges help to diagnose and repair high pressure on the high gauge. This is usually caused by low airflow through the condenser. Common causes are a worn-out fan clutch, malfunctioning electric cooling fan or debris in the condenser. Left unrepaired, high pressure can result in excessive wear on the A/C compressor and poor cooling.

Another common problem is very low, low-side pressure. This is usually caused by a clogged or defective expansion device.

There are many more possibilities for why an auto air conditioning system might not work properly. They range from

a blend air door not completely closing off the heater core to a water valve not completely shutting off the flow of hot water to the heater core.

Rely on Kent Auto Repair, Your Skilled A/C Technician

Your auto air conditioner system has many ways to fail. The answer to the question, “How much it will cost?” requires a diagnosis by a skilled A/C technician. At Kent Auto Repair, we have decades of experience diagnosing and repairing automotive air conditioning systems. Let us make your car cool again.