Airflow and Charge Check FAQs

For homeowners who want to ensure proper central air conditioning or heat pump installation.

What is Airflow and Charge Check?

Airflow and Charge (AC) Check is a test procedure developed to verify that a new central air conditioning or heat pump installation has been properly adjusted to deliver optimal comfort, efficiency, and savings. An AC Check- trained installer will test the refrigerant charge and air flow to verify it is set to deliver proper comfort and performance. Repeated national studies have shown that as many as two out of three new installations have improper charge or improper air flow for the customers’ location. Air conditioning systems that pass an AC Check will operate more efficiently, meaning it's less expensive to operate, and should last longer with fewer repairs.


My central air conditioning or heat pump system is new. Shouldn’t the amount of refrigerant charge be correct?

Even newly installed air conditioning systems or heat pumps are often incorrectly charged, especially if the line between the indoor unit and outdoor unit is longer than is standard. All central air conditioning and heat pump equipment is delivered with a standard factory refrigerant charge of 15 feet of line set. That means if the outdoor and indoor units are within 15 feet of each other, there is adequate charge. Most installations will be farther than 15 feet apart, so the installation contractor must add the correct amount of additional refrigerant to get optimal performance.


If we are getting cool air from the system, how bad can a refrigerant charge problem be?

Incorrect charge significantly reduces the cooling capacity and energy efficiency of your unit and can also damage your system. If a unit is significantly undercharged, the compressor can overheat, causing it to burn up internally. Overcharging can flood the compressor with liquid refrigerant, causing the piston to fail. In both cases, premature compressor failure is the likely result.


How can I have an airflow problem if my system is blowing cool air?

All rebateeligible central air conditioning and heat pump systems include a high-efficiency ECM (electronically commutated motor), multi-speed blower. It is set at the factory, based on the typical mid-range of its capacity, which might not be the best setting for your home or duct system. When systems leave the factory they are shipped all across the country, so the system needs to be set to perform optimally in the climate where it is installed.
When the airflow is too high, your system will have difficulty removing humidity from the air, leaving your house cool but humid. If the airflow is less than manufacturer's recommendations, your system will have to operate much longer to cool your house, and may even cause your system to eventually ice up, leaving you with no air conditioning, and possibly a damaged compressor.


What does a technician do when performing an Airflow and Charge Check?

The participating AC Check-trained contractor will measure refrigerant temperatures and pressures outside, indoor return and supply temperatures and humidity levels, plus indoor and outdoor electrical measurement at the equipment. The testing must be done when it is at least 60 degrees Fahrenheit outside and not raining – even warmer weather is preferred. Measures are reported through the Mass Save® AC Check software, and test results are delivered.
When selecting a contractor to install your new central air conditioning or heat pump system, choose an AC Check-Trained Contractor to ensure you get the performance you paid for.

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