Sunday, June 17, 2012

Expensive Top Offs

For years, many technicians and customers have been content to “top off” leaky air conditioning units, feeling the time and expense required to find and repair small leaks exceeded the inexpensive price of adding a few pounds. After all, adding refrigerant is pretty easy, does not take long, and most customers were perfectly happy to have their systems gassed up every so often. With the cost of adding refrigerant steadily rising, the era of cheap “top offs” is coming to an end. Newer units also hold considerably more refrigerant than older models, and the refrigerant is quite costly. A bill of $500 for “topping off” a system is quite possible. At $500, I don’t want to call you back next month for a repeat performance. I want the problem fixed. Customers are going to start demanding that we fix the leaks – not just gas up the units.

The temptation to just add refrigerant is strong. Locating and repairing leaks takes time and there is really not a sure-fire leak test that can prove a charged system has no leaks. We detect the refrigerant coming out to prove a leak. However, not finding any leaks does not necessarily mean there are none – it just proves that you did not find them. Like many things, better tools often yield better results. Everyone should have a good electronic leak detector and good quality soap bubbles that will form micro-bubbles. An ultrasonic detector is also a good idea for detecting leaks using nitrogen. You also need to use the tools enough to feel confident and comfortable using them. A fancy electronic leak detector is not much help if you don't trust it or use it .

Some leaks are really not repairable. Take for an example an evaporator coil with multiple pin-hole leaks. Plug a little hole today and a new one springs up tomorrow. The repair is to replace the coil, which is expensive. However, not replacing the coil is also expensive. Not only is the cost of adding refrigerant quite high, so is the cost of electricity. A system with a leak loses capacity and efficiency from the day it is charged. The unit has to run longer and longer to accomplish less and less, until it simply can’t meet the demand. The combined costs of added refrigerant and increased operational cost can add up to the cost of replacing the coil. Topping the charge off is no longer an easy and inexpensive solution. It is now just the lazy and expensive cop out.


  1. Thank you for sharing this article with us Carter! I was actually online looking at different hvac in Austin options when I came across your blog. You have been a huge help and provided a lot of information about HVAC that I did not know. Thank you again for sharing and helping out others like me who are pretty ignorant on the subject of HVAC.

  2. There are a couple different ways to clear a clogged condensate line, including using a wet/dry vacuum to suck out the clog. But my favorite method is to use a product called Mighty Pump. It's a powerful hand pump that can be used to suck or blow lines clear. Invented by Stuart Oakner, a licensed air-conditioning contractor with more than 30 years experience, the Mighty Pump is available online for about $60.

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