What Happens When Too Much Refrigerant is Added to a Car's Air Conditioning System?

[LeAllison]

Adding too much refrigerant to a car's air conditioning system can increase the pressure within the system. When the air conditioning control system detects excessively high pressure, it will frequently cut off the compressor's operation, leading to poor cooling performance. Additionally, the consistently high pressure in the air conditioning pipes can cause damage to the system's components. Below is a detailed introduction regarding the addition of refrigerant to the air conditioning system: Function of Refrigerant: The role of adding refrigerant to the air conditioning system is to enable cooling. Only by serving as a refrigerant within the air conditioning system can it effectively regulate the indoor temperature. Cooling Principle: The air conditioning compressor primarily draws gaseous Freon from the evaporator into the main unit. After undergoing compression, it is converted into a high-temperature, high-pressure gas, which is then sent to the condenser via an expansion valve. After dissipating heat, it becomes a low-temperature, high-pressure liquid. Although the air conditioner itself blows out hot air, after undergoing low-temperature and high-pressure processes, the Freon passes through the capillary tube and flows into the evaporator for throttling. The space expands, and the pressure decreases, converting it into cold air, thus blowing out cooled air. Frequency of Adding Refrigerant: During the operation and use of the air conditioning system, if the Freon becomes insufficient or leaks, even if all other components of the air conditioner are functioning normally, the system will not be able to provide cooling or heating. However, as long as the air conditioning system is sufficiently sealed, no matter how long it has been in use, there is no need to add Freon, and the cooling and heating effects can remain excellent. If it is necessary to add Freon to the air conditioning system, it should only be done when there is a shortage or leakage of Freon.

[OGage]

Overcharging refrigerant is a serious issue. My neighbor tried to save money last month by having someone improperly top up the Freon, and his car ended up roaring like a tractor. When the compressor is overloaded, it spins wildly, causing the high-pressure pipeline to surge into the red zone. Excess liquid refrigerant in the evaporator can't vaporize and absorb heat, blocking the cold air output. The cabin temperature wouldn't drop, and fuel consumption skyrocketed. When I accompanied him to the repair shop, the high-side gauge needle was pegged at maximum. The mechanic warned that prolonged operation in this state would definitely damage the compressor, requiring immediate removal of excess refrigerant and a complete vacuum recharge. Always test high and low pressure ranges with gauges before refilling—for passenger cars, maintaining 30-50psi on the low side and 150-250psi on the high side is safest.

[Franklin]

When the refrigerant in the car's air conditioning system exceeds the standard level, the system pressure will definitely be too high. I often encounter this situation in the workshop. Not only are the pipeline connections prone to leaks, but the wear on the compressor bearings accelerates threefold, and the pulley makes a very noticeable squeaking noise. The most annoying part is that the cooling efficiency actually decreases, and customers always complain that the AC isn't cold enough, with the dashboard vent thermometer still showing temperatures above 15°C. In fact, frost on the low-pressure pipe is a classic sign, indicating that liquid refrigerant is flowing back and clogging the expansion valve. Every time I handle this, I first connect a recovery machine to remove the excess refrigerant, then test whether the compressor lubricating oil has been diluted by the refrigerant. Otherwise, the entire refrigeration system will likely require a major overhaul within six months. Remember not to exceed the weight marked on the refrigerant canister—for ordinary household cars, 500-800 grams is usually sufficient.

[MacSara]

Overfilling refrigerant is absolutely counterproductive, as I learned the hard way with my own car. After the last maintenance, the AC suddenly stopped cooling. Upon inspection, it was found that the refrigerant was overfilled by 20%. The compressor kept engaging protection mode, causing the clutch to frequently disengage. The air from the vents alternated between hot and cold, electricity consumption skyrocketed, and the battery was prematurely worn out. The mechanic mentioned that repeated triggering of the high-pressure cutoff switch is actually quite dangerous, as refrigerant line pressures exceeding 400 psi could cause pipe bursts. Now I always supervise them weighing the refrigerant with an electronic scale during refills. It's recommended to check residual levels every two years—only top up R134a refrigerant when the loss exceeds 15%.