Mastercool 99773-AR HVAC Digital Manifold User Manual
Page 5
5
www.mastercool.com
Subcooling is the difference between the boiling point of the refrigerant in the condenser
(saturated temperature) and the actual temperature (sensor temperature) of the
refrigerant as it leaves the condenser. The degrees that the refrigerant “cools down” below
the boiling point is the sub-cooling. Under worst case scenario low load for thermostatic
expansion valve systems (TXV) the subcooling will continue to rise. If the subcooling rises
too high, liquid may be backed into the compressor causing damage and failure.
On TXV systems, the subcooling is the best indication of the state of the charge in the
refrigerant system since these systems are designed to maintain constant superheat.
Properly charging a system ensures maximum efficiency and longer equipment life.
Use caution whenever working with electricity and high-pressure
liquid or gas. Always wear safety glasses.
Follow all instructions provided with equipment being serviced or installed.
TARGET SUPERHEAT AND SUBCOOLING
Follow all equipment manufacturer’s specifications, warnings and suggestions.
To determine the target superheat (fixed orifice system) or subcooling (charts vary
dramatically from one system to another), you will typically need three things. Outdoor dry
bulb (outdoor air temperature), indoor wet bulb, and the manufacturers target superheat
chart or subcooling chart.
You can use Mastercool part number 52232 Humidity Temperature Meter for both indoor
wet bulb and outdoor dry bulb.
GENERIC TARGET SUPERHEAT & SUBCOOLING CHARTS*
*The required superheat chart is an example of a generic superheat chart of a typical fixed
orifice, split residential system. The required subcooling chart is an example of a typical
chart for a TXV, split residential system. These charts should not be used for charging.
They are only examples to show what the manufacturer’s charts may look like. Follow all
manufacturer’s indications, instructions and warnings above those in this manual.
The indoor wet bulb measurement should be taken as close to the evaporator coil
inlet as possible. The outdoor dry bulb reading should be taken as close to the
condenser air inlet as possible.
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CLEANING THE SENSOR
(SEE FIG. D)
Observe the gasket after each vacuum. If oil is present, it is possible that there is a
presence of oil in the sensor chamber.
Follow these instructions:
1. Disconnect the sensor chamber from the socket.
2. Remove the gasket & depressor from the assembly to clean.
3. Clean the gasket. Rinse the sensor chamber with acetone. Repeat until the oil is
completely removed. Allow 2 – 4 hours for all of the parts to dry.
4. Reassemble all of the parts and check the unit.