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Question: Where should I look for refrigerant leaks on my AC unit?

ultrasonic leak detector

Question: My air conditioning system is leaking refrigerant somewhere? Every year we have to call an HVAC company to charge our system which is quite expensive! Where should I look for refrigerant leaks on my AC unit? Where are the most common places in the air conditioning system where leaks are found most often?

Answer: We have this question asked quite often. Finding refrigerant leaks is probably the most difficult joy that an HVAC tech has to do. Refrigerant leaks can be found in easy to see places or in almost impossible to see places. When I was doing HVAC service work if I did not see any leaks (oily spots) on the outdoor unit or oily spots on the refrigerant line set I would inject fluorescent dye in the system, allow the dye to circulate for a few days then come back with a black light in dark conditions to try and find the leak. Most leaks that I found were in the indoor evaporator coil. The dye was good but time-consuming. It was good that I could show the customer where the leak/leaks were, but bad that I had to make two trips and spend lots of time uncovering the evaporator coil to see the leaks. Probably 90% of the time the customer needed a new evaporator coil to stop the leaks. Below we have a really good YouTube video made by AC Service Tech LLC that explains and shows the top 10 spots where air conditioner leaks occur most often. Thanks so very much to AC Service Tech LLC for making this excellent YouTube Video! AC Service Tech uses an ultrasonic leak detector to find many of the leaks in this video. I sure wish they had ultrasonic leak detectors when I was doing service work. Those ultrasonic leak detectors are not cheap about $450 to $600, but seem to be really good!  Here is the written list of the 10 most common spots where refrigerant leaks are found. The YouTube video is really good at explaining these leaky areas in more detail. If you have any questions please comment below or email us anytime arnoldservice@gmail.com We would love to help you out and earn your business!

Here are the top 10 spots where leaks in air conditioners and heat pump occur most often:

  1. Leaking Shrader valve caps or sometimes called Schrader valve cores. Make sure the Schrader valve caps are in good condition. We sell a set of 10 really good Schrader valve caps on the following page. Please click here if you are interested in seeing the Schrader valve caps that we sell.
  2. Leaking on the indoor evaporator coil where the tubing goes through the galvanized tin.
  3. Leaking in the joints of the evaporator coil tubing where the tubing is brazed together.
  4. Leaking in the refrigerant distributor tubes at the evaporator coil.
  5. Leaking in the middle of the tubing in the evaporator coil. The tubing is extremely thin.
  6. Leaking “O” rings on the outdoor service valves.
  7. Leaking outdoor condenser coil.
  8. Leaking filter driers where brazing has burnt the paint off the drier and rusted over time. Poor brazing on the filter driers.
  9. Leaking accumulator tank. Some AC units and many heat pumps have accumulators than are prone to rusting and leaking.
  10. Leaking bottom tubes on the condenser coil where leaves and debris have been allowed to accumulate causing the tubing to rot and leak.


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