Charging and Recovering with MeasureQuick
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Inside the Kalos HQ, Jim notices that the liquid line filter-drier sounds like it contains refrigerant that’s flashing off. MeasiureQuick shows that the subcooling is VERY low (0.5 degrees; the manufacturer target is 11 degrees) and that the head pressure is low. The evaporator also doesn’t have an even amount of moisture across the coil, the system capacity is low, and the SHR is 0.8, which is a bit too high for a humid climate. All the signs indicate that the refrigerant charge is low.
Before charging the system, Jim is sure to purge the hoses. He also uses a valve core depressor to add or remove refrigerant more precisely. Jim slowly adds vapor refrigerant to the suction line and checks his subcooling. MeasureQuick sets a subcooling target within 3 degrees of the manufacturer’s target, so Jim adds refrigerant until the system gets 8-14 degrees of subcooling.
After Bryan and Jim add the charge, the system has high suction pressure and low superheat (a bit more so than usual). The subcooling is just slightly overshot due to a quick charge, and the liquid line temperature is a bit low. MeasureQuick determines that possible faults include a loose TXV bulb, liquid line restriction, overcharge, or a dirty condenser. In the end, the system has just been slightly overcharged, so Jim recovers the charge.
After the recovery, the latent capacity improves, as does the subcooling. The superheat is still low, but it’s normal for that particular system. Having slightly high subcooling probably won’t be a huge deal, but it’s always worth taking the time to do the job right.
When Jim and Bryan go back inside, the liquid line drier is a lot quieter and doesn’t have the pulsation it used to have.
So, the lesson for today is to take your time and don’t film videos while charging a system.