The most common refrigerant is R-134A (or HFC-134a) however newer vehicles may use R-1234YF (or HFO-1234yf). Even still, some very old vehicles may also be using R-12 (or Freon). The easiest way to know is to check your vehicles A/C system nameplate under the hood.
As an air-conditioning refrigerant in newer automobiles, the optimal running pressure for R134A is between 22 and 57 pounds per square inch.
Vents are blowing warm air
Without enough refrigerant it needs, your air conditioner can't absorb the heat in the air. This will result in air coming out of your vents that is not cool enough, or maybe even warm. You may even have less air blowing out of your vents.
Should You Recharge Your A/C Unit For Optimal Performance? The short answer is no; you don't need to recharge your AC unit on a set schedule. In fact, most units only need to be recharged once every two to five years – and sometimes even longer than that.
Your air conditioner has a set level of refrigerant inside it, referred to as the AC's charge. This level will not lower over the air conditioner's lifetime… unless it develops a leak.
Unless there is an actual hole or crack within the compressor holding the freon, the freon level remains the same. Therefore, an AC will never require a recharge of freon unless without the presence of a leak.
Without any refrigerant at all, your air conditioning system would be incapable of cooling your home. But if you have low levels, you may still be able to feel some cool air from your system.
Hissing sounds are indicators of the refrigerant escaping in the form of gas. On the contrary, bubbling sounds are an indication that the refrigerant is escaping in the form of liquid. This is the most common sign of a refrigerant leak since not many other AC issues cause these noises.
The general guideline used when calculating the amount of Freon in a residential A/C unit is 2-4 pounds per ton of cooling. For example, if you install a new A/C system rated for a five-ton load, the system will require 10-20 pounds of refrigerant.
Under EPA regulations, only a certified professional can recharge your home's HVAC system. You should never try to recharge the A/C yourself, even if you have a home air conditioner recharging kit. The refrigerant used can be harmful to you and the environment if it's not handled properly.
Don't. The U.S. Environmental Protection Agency (EPA) recommends not replacing Freon or refrigerant by yourself for both health and environmental reasons.
Freon (which is really just a particular brand of refrigerant) lasts forever. It's not like gas in car; it does not get “used up.” You see, your air conditioner's refrigerant system is a “closed/sealed system,” meaning that it does not allow refrigerant to escape in any way.
1 How Long Does Refrigerant Last? In most cases, refrigerant in a central air conditioning should last for the life of the system. As long as your HVAC system is kept in good working order, you should never have to worry about replenishing it.
Frozen Refrigerant Lines: When the system is too low on refrigerant, the evaporator coil can get too cold. This causes ice to build up on the coil itself, but also on the surrounding components of your air conditioner. If you notice an ice build ups on your air conditioner, this is most probably the reason.
The Consequences of an Overcharged Air Conditioner
One major problem is that when there's too much refrigerant, it won't be able to properly switch between gaseous and liquid state, and more of it will remain in liquid state. This will harm the system's efficiency and affect cooling in the house.
For a good charge, the low-pressure gauge should read between 25 and 40 psi (pounds per square inch), and the high pressure gauge should read between 225 and 250 psi.
Note: The most ideal pressure readings are around 150 high and 30 low.