2. EXPANSION VALVE SYSTEM
1. Purge gauge lines. Connect service gauge manifold to base-valve service ports. Run system at least 10 minutes to allow pressure to stabilize.
2. Temporarily install thermometer on liquid (small) line near liquid line service valve with adequate contact and insulate for best possible reading.
3. Check subcooling and superheat. Systems with TXV application should have a subcooling and superheat of 9 ±3 ºF.
a. If subcooling and superheat are low, adjust TXV to 9 ± 3ºF then check subcooling.
b. If subcooling is low and superheat is high, add charge to raise subcooling to 9 ± 3ºF then check superheat.
c. If subcooling and superheat are high, adjust TXV valve to 9 ± 3ºF then check subcooling.
d. If subcooling is high and superheat is low, adjust TXV valve to 9 ± 3ºF superheat and remove chargeto lower the subcooling to 9 ± 3ºF.
NOTE: Do NOT adjust the charge based on suction pressure unless there is a gross undercharge.
4. Disconnect manifold set, installation is complete.
Subcooling Formula = Sat. Liquid Temp. - Liquid Line Temp.

3. SUPERHEAT METHOD
THE SUPERHEAT METHOD IS USED FOR SYSTEMS USING A FIXED ORIFICE TYPE METERING DEVICE
Orifice
Metering
Device

4. USING SUPERHEAT CALCULATOR
GET THE RETURN WET BULB TEMPERATURE AT THE RETURN AIR GRILL USING A SLING PSYCHROMETER OR METER CAPABLE OF READING WET BULB TEMPERTURE
GET THE OUTSIDE AMBIENT TEMPERATURE IN THE SHADE OF THE CONDENSING UNIT
SET ARROW TO INDOOR ENTERING AIR WET BULB TEMPERATURE
LOCATE CONDENSER ENTERING AIR DRY BULB TEMPERATURE
READ REQUIRED SUPERHEAT TEMPERATURE AT CONDENSER ENTERING AIR DRY BULB TEMPERATURE
ADD CHARGE TO LOWER SUPER HEAT
REMOVE CHARGE TO RAISE SUPERHEAT

5. USING SUPERHEAT TABLE
GET THE OUTSIDE AMBIENT TEMPERATURE IN THE SHADE OF THE CONDENSING UNIT
GET THE RETURN DRY BULB TEMPERATURE AT THE RETURN AIR GRILL
INTERSECT THE 2 NUMBERS
THAT WILL GIVE YOU THE AMOUNT OF SUPERHEAT YOU NEED

6. Super-heat and Sub-cooling charts
The super-heat and sub-cooling charts will be posted on the back side of the control door.

7. EXAMPLE
AMBIENT OUTSIDE TEMPERATURE (IN THE SHADE OF THE CONDENSOR) IS 95 DEGRESS
RETURN AIR (DRY BULB) IS 75 DEGREES
INTERSECT THE 2 NUMBERS AND YOUR SUPER HEAT WILL BE 5 DEGREE

8. INSTALL THERMOMETER INSTALL ON THE SUCTION LINE ( LARGER LINE )
INSULATE THE PROBE FOR AN MORE ACCURATE READING

9. READING THE SATURATED EVAPORATER TEMPERTURE
ON THE LOW SIDE OF YOUR COMPOUND GAUGES ( BLUE )
THE OUTSIDE READING IS YOUR PRESSURE
THE INSIDE (R 22) IS YOUR SATURATED EVAPORIZING TEMPERTURE

10. EXAMPLE YOUR LOW SIDE PRESSURE IS 75 PSI
DIRECTLY BELOW THAT NUMBER IS THE SATURATED EVAPORIZING TEMPERATURE, WHICH IS 44 DEGREES
TAKE YOU SUCTION LINE TEMPERTURE, WHICH IS 65 DEGREE

11. EXAMPLE SUBTRACT THE 2 NUMBERS AND THAT HOW MUCH SUPEREHEAT YOU HAVE
=21 SUPERHEAT
WE ONLY NEEDED 5 DEGREES
ADD CHARGE TO LOWER SUPER HEAT
REMOVE CHARGE TO RAISE SUPERHEAT

12. Charging Two Stage Units
Set unit to operate at low stage cooling.
Operate for 10 minutes.
Check and record low stage liquid pressure at the service valve.
Set thermostat to operate at high stage.
Check and record high stage liquid pressure at service valve.
Explain that since 2 stage-procedures are different

13. Charging Two Stage Units
The high stage pressure should be noticeably higher than the low stage liquid pressure.
If the pressures are identical, the compressor did not switch from low to high stage.
Verify wiring and t-stat settings.
Run the unit on low stage and make the final charge adjustments on low stage.
Do not adjust charge to change sub-cooling on high stage. Charge adjustments must only be made under low stage cooling.
Verifying unloader is working

14. For technician use to refer to only

15. Complete chart in the I/O and Service manual