What Cause Aircon Gas Is Leaking
The refrigerant (commonly known as FREON) is not a magic substance, it is not cold by itself. Scientists around the world are busy trying to find that magic substance and we're not too sure if anyone's found that. What we are very sure is that refrigerant used in your air conditioner is definitely not that magic substance. Do not be mistaken that if you add more FREON into your system, your air conditioner will be cooler. In fact, the opposite will be the result.
The fundamental of air conditioning is the use of a compressor to compress and decompress the FREON. It is through the manipulation of the gas pressure that created the temperature difference; thus it is very important for an air conditioning technician to be well versed with the enthalpy chart of different types of refrigerant before meddling with the gas.
If too much liquefied gas is produced by over charging your system, this is a condition called “evaporator flooding”.
Meaning, the entire blower is filled with liquefied Freon, thus, leaving no more room for evaporation to take place. This explains why adding more gas into the system WILL NOT make your system any cooler, but rather it will encourage liquid FREON return which (if exceeds your manufacturer’s specification for the critical amount of gas to go into your system), WILL cause permanent damage to your compressor due to 2 reasons. First, the liquefied Freon returning to the compressor will dilute and damage the compressor oil, causing premature wear and tear. Secondly, as liquid cannot be compressed, sending liquid directly into the compressor will cause serious damage to your compressor.
What causes Aircon Gas Leak?
Your aircon shouldn't leak gas at all; if it was properly set up, gas will not leak even after 10-20 years! Now, lets take a good look at high risk areas where gas leaks often occur.
Located at the condenser, you'll see all these nuts. Some condenser have a cover so you may not see them. These nuts must be properly tightened. If they are not properly tightened, gas can leak from there.
Since the copper pipe is soft , once tightened, it forms a very good seal. But over tightening can cause it to crack.
Great care must be taken when forming the flare; if the flare is not formed well, with ripples, it may cause gas leak too.
Inside the condenser
If any 2 pieces of copper pipes were accidentally touching one another, the vibration caused by the compressor can soon rupture a hole in the pipes, causing gas leak. Since the pressure inside the condenser is a lot higher when compressor is running (~250psi for r22 refrigerant and 350psi for r410 refrigerant), a leak in the condenser will usually be fast, at most 1 week and it'll all leak out. PS: the pressure of your car tire is only ~30psi
The compressor sits on top of 3 pieces of rubber shock absorbers. Since the compressor is hot, and if the shock absorber is made of inferior quality, it may melt or soften. This will cause the compressor to either tilt to one side of simply lower by an inch. It is often this condition that causes two pipes to touch one another.
When technician over-charged the gas system, it causes the compressor to overheat, thusincreasing the risk of damaging the shock absorbers. On top of that, an over charged system causes the compressor to vibrate vigorously, thus touching pipes that were marginally apart.
It leaks at the pipes, severity determined by rate of leak:.
a) It leaks every few years.
If it runs out of gas every few years, it is a really tiny gas leak. Don't bother conducting pressure test nor an other sort of test, its not worth spending that kind of money. Assuming your aircon will last you 10 years, so at most you'll top it up 10 times. Troubleshooting and replacing the pipes will cause you more than that. Don't worry, modern refrigerant gas is not flammable and is not harmful to the human body unless taken in huge amount ( i mean really HUGE amount). In the olden days, ammonia gas was used as refrigerant and this gas is highly toxic (fatal), but those are history.
b) It leaks in a couple of months time.
This rate of leak is definitely disturbing and most likely frustrating. But technically speaking, this is still a very small leak and any attempt to isolate the problem (not pin point) will be very costly especially if it is a multi split aircon. If you are lucky, it leaks at places that are not concealed. There will be traces of oil at the place of leak. If leak can be picked up visually, all it takes is to spot weld the leak and recharge the gas, total repair cost will be $160/hr (inspection) + blazing
($168), gas recharge ($90 to $250), total ~$400-$700.
But, If visual inspection cannot detect any traces of oil, the leak might be occurring in the concealed copper pipes. Pressure testing ($200 per set of pipe) will need at least half a day before we see any significant drop in gas pressure.
Note: your condenser liquefies the refrigerant gas by compressing said gas by ~600 times. Therefore, if we conduct pressure test by using compressed air instead of liquefied gas, the rate of leak will "improved" significantly by approximately 600 times. Therefore, what that took 90 days (2160 hours) to leak can be revealed in ~2160/600 = ~3.5 hours.
Therefore, we come in, set it up and back in the evening to monitor if pressure drops. But such test can only isolate which pipe and blower set is leaking, it does not pin point. If you want to further isolate whether it is the pipe or blower, the pressure test must be repeated at $200, and another day without aircon.
If it leaks at the connecting pipes, the pipes must be replaced. Depending on whether you want to run the new pipes concealed or externally (with casing), pipe replacement is not cheap, and depending on the level of difficulty, pipe replacement, will cost a minimum of $300 - $500.
But, the test itself (assuming a system 4) would have cost you $800. Making total repair cost ~$1300.
Therefore, gas leak can be a very painful experience for any house owner.
c) It leaks in a few days.
This is better indeed, leak will most likely be occuring in the condenser and can easily be picked up visually. Provided that it leaks at copper pipe sections and accessible, all it takes is to spot weld the leak and recharge the gas, total repair cost will be $90-$300 (inspection) + blazing ($168), gas recharge ($90 to $250), total ~$350-$700