Tech method lesson 2B.txt

    • author "me"
    • tags "Cooling 101"
    • description ""
    • fileName "Tech method lesson 2B"
    • freezingBlueDBID -1.0
    • Low superheat
    • Only a low superheat measurement can indicate flood back.
    • Superheat tells us if there is too much or not enough refrigerant on the low side of the system.
  1. Heat load
    • Anything which adds heat to the evaporator will boil off more refrigerant.
    • Anything which interferes with the coils ability to absorb heat will lower the superheat.
    • We must check the evaporator fan, motor, coil, filter, and airflow before measuring the superheat.
  2. Compressor vacuum test
    • Reciprocating compressor only
    • Shut off the flow to the metering device via the liquid line service valve.
    • Can shut off suction as long as you have a true suction port (HP must hold RV in position).
    • Compressor should be able to pump 15" ~ 20" of vacuume and jold.
    • Ensure condenser can hold total refrigerant charge.
  3. Symtoms of an inefficient compressor
    • Low discharge pressure
    • High suction pressure
    • Low superheat
    • Low subcooling
    • Equalized pressure (no pump cmpressor)
    • Low evaporator t.d.
    • Low condenser t.d.
    • Will not pump down
    • Will not hold vaccume when pumping down.
    • Will not build head pressure (disconnect outdoor fan)
    • Low compressor amperage.
    • Compressor too quite or too loud. (Mechanical failure)
  4. Evaporator temperature
    The evaporaing temperature should be at least 35 dgrees below the space temperature at design conditions.
Card Set
Tech method lesson 2B.txt