Freon Charge

Proper Refrigerant Charge

Over half the installed systems have the wrong refrigerant charge. We lost count of the number of newly constructed houses and newly installed air conditioning systems we have looked at for the first time that had the wrong refrigerant charge. Many home owners find this hard to believe especially since the air conditioning system is working . The most common measurement for a working air conditioning system is if it is blowing cold air. Not is it blowing cold air at the lowest possible cost. An overcharged system will blow cold air but use more electricity. An undercharged system will blow cold air but use more electricity. Both situations lower the life expectancy of the air conditioning system. Not to the point it breaks to tomorrow. A life expectancy of a air conditioning system is many years. Overcharging and undercharging shrink the number years the system will operate.

Save yourself money

Here is a list of common methods for charging air conditioning systems.

  • Manufacturer's recommendations
  • Superheat Method
  • Sub cooling Method
  • By Weight
  • By instinct, pressure, experience, beer can cold method
  • Let's detail each of them but lets say first without air flow within operating specifications you will end up in a situation of just making the system blow cold air. The second most critical is to let the system run several minutes so accurate measurements can be taken. Think of you car on a hot day. You get in it and start it up. It takes a few minutes before you get that cold air you so desperately need. House air conditioners are not any different. This second step takes patience is skipped frequently. The third most critical is having a matched system. In short a matched system is a system tested by the manufacturer so they can provide refrigerant charging data.

    Manufacturer's recommended method

    This is the method recommended by the manufacturer. Documentation for this at the very least available from the manufacturer but it frequently posted on the inside access panels of the system. They almost always were kind enough to tell you exactly how to do it so there is very little excuse for not using this procedure.

    Superheat Method

    This charging method is one used with systems using orifices or capillary tubes. This method will get it close in most instances but it not a replacement for the manufacturers method. Superheat should always be checked and is an invaluable diagnostic measurement. It is frequently part of the manufacturer's charging procedure.

    Sub cooling Method

    This charging method is one used with system using TXV's (thermostatic expansion valves). This method will also get you close in most cases but is not a replacement for the manufacturers procedure. Sub cooling should always be checked and is an invaluable diagnostic measurement. It is frequently part of manufacturer's charging procedures.

    By Weight

    This method is most used after performing a repair on the refrigeration system that required evacuation of the system. All systems post a refrigeration weight on there Model and Serial numbe information sticker like 6lbs 5oz or something similar. This is a great way to get you close to the proper charge but not a replacement for the manufacturer's procedure.

    Instinct, pressures, experience, beer can cold method

    In this day and age, it is a shame we have to even address these methods. Arguably each one of them is a useful diagnostic tool for identifying a sick system. NONE of them are an accurate way to charge a system. Any technician using these should be asked to leave immediately and you should refuse payment.

    Gold standard Gold Standard

    This gold standard is the manufacturer's recommended charging method. This is best and only way to properly verify the charge of an installed air conditioning system. This is the method used by the AHRI (Air Conditioning, Heating and Refrigeration Institute) when verifying the system operating efficiency (SEER, EER stated by the manufacturer). Why is this not done every time all the time? It comes back to education, time and variations in the process.

  • Education
  • A lot of technicians just have not had the proper education. Most are taught how to make air conditioners blow cold air not to verify the system is charged properly.

  • Time
  • It takes time to properly verify a system's refrigerant charge. 15-20 minutes if the refrigerant level is correct. If it needs adjustment figure 45 minutes to an hour. If the system is over charged, refrigerant needs to be taken out of the system. Now you need equipment to do this specifically a recovery tank to put the refrigerant into. It is illegal to release it into atmosphere. I would compare it to dumping your used motor in your street gutter. It is just plain wrong. This too takes time.

    You want the gold standard!

    You want to save money!

    We can't promise you will get the gold standard but we can help weed out the ones that will definitely not provide it thus giving you the best possible chance of having a properly charge system.

    Have the following documented on the invoice and have the technician sign it:

  • System air flow
  • Which charging method was used. Ask why the one used was if not the manufacturer's method. This usually means something is wrong or the technician is short cutting or unknowledgeable
  • Indoor Dry bulb and wet bulb temperature
  • Outdoor Dry bulb and wet build by the condenser
  • High and Low refrigerant pressures and saturation temperatures
  • Superheat measurement and sub cooling measurement
  • The manufacturers projected measurements based on the above operating conditions
  • How far off are your system's measurements? They are rarely right on but should be very close.
  • If the technician will not provide this information, refuse to pay, ask them to leave and call another company. Them telling you is not good enough. Have them write it down and sign it. If you experience resistance from the technician or the company, tell them you will take your case to the BBB, local licensing agency and the manufacturer. I would most likely skip to the last one first. Most manufacturers are very receptive to customer complaints.

    When you get this, it cannot 100% guarantee it is right since you don't have the knowledge or tools to verify it. It does provide a good chance the technician knew what he was doing and attempted to get it right. They attached their name to it and the companies creditability to the work. If you have to pursue means for satisfaction in the future, you have documentation to refer back too. As the consumer, you have the leverage and the ability to demand quality.

    Hold you service provider accountable and save some money.