I apologize for the parts and length of this article, but I'm getting a bit frustrated after trying to explain why a leak search and repair is so expensive. Customers expect this to be done for under $300 and I have to quote closer to a grand. I've been on a few jobs and the one of the most frustrating and time consuming aspects of this job, (besides arguing with customers over our rates) is looking for a refrigerant leak on an air conditioning system. Usually, the the culprits are related to careless install practices or poor maintenance. This includes, but in no way limited to, clogged condensate drains, improperly placed distributor tubes (getting hung up in standing water) or sub par (I hate this word) joining methods. I've seen installers use plumbing solder and not tighten fittings correctly. I hate to say it but have also had customers and salespeople mess this up royally and install a 410 heat pump on a belt driven blower furnace. Since R410 or Puron works at a 1/3 higher pressures than R22 or Freon 22, these fittings will work loose. I went back to a job, three times on one of these. It made me look horrible and the boss wasn't impressed, but I didn't sell nor install it. I digress. Another very common problem on mini-splits (those cute little Mitsubishi and Daiken, etc) are improper flaring and tightening of fittings. R410 fittings require a special flare as the single flare for R22 will not hold up. Any job worth doing is worth doing well.
Of course, there's always vandalism and equipment failure. Someone will try and cut a condensing unit loose for scrap or deliberately sabotage a system. Fan blades will break off and mangle a condenser coil or a compressor will call it quits and spring a leak. Sometimes vibration on thin copper or aluminum tubing will cause it to fatigue and break. As always, these will be in the worst possible spots to get a torch or replace a part or they'll be on a roof or in a crawl space.
Another obvious cause of leaks is just age. Even though a homeowner will call a 12 year old system "new" and a 6 year old car "old," the truth is that most air conditioning systems last between 12 and 18 years before they get a leak. Improper maintenance or poor installation may reduce this by half. Accidents also happen and these would require a small encyclopedia to list. I will say most aren't really accidents at all, but the result of carelessness or poor planning. Had a customer complain bitterly to me recently about corrosion on an outdoor (condenser) coil a few weeks ago and even turned it in to their insurance. It wasn't the fault of the manufacturer, nor the installer. However, animal urine and some lawn treatments can destroy a condenser coil. It was the latter in this case and now a 7 year old unit could have a leak in the near future.
An air-conditioner is just a way of removing heat from one place and transferring it to another. It's not unlike bailing water out a leaky boat. The indoor coil absorbs the heat and the outdoor coil gets rid of it. In a heat pump, it harvests the heat from the outside and the indoor coil puts in the house. The refrigerant (customers call it "coolant") is just a heat sponge for the system; as it boils and evaporates it soaks up the heat and at it becomes a liquid cools off and gets rid of the heat. What a leak does is reduce the size of that heat sponge to the point the air-conditioner is no longer effective. In part 2, I'll go more into finding and fixing a leak, the right way. Maranatha!