System information

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Task Tech Initials
Suction Piping Procedure: Keep tubing sealed while running to connection points. Fit suction
tubing to evaporator outlet connection. It is recommended to t a Schrader Type Access valve at the
evaporator to allow for superheat checking and a micron gauge attachment. Fit suction tubing to
condensing unit suction service valve port. If there are no ttings along the length of the suction tub-
ing, slide the Aramaex insulation over the tubing for the entire length of the tube or apply as conve-
nient. Keep end of tube sealed during this procedure. If there are brazed ttings along the length of
the tube, apply the insulation after leak testing.
Energize the fan coil unit solenoid valve, open Nitrogen valve to bleed Nitrogen from liquid line
service valve through liquid line and suction line. Loosen suction gauge hose to relieve pressure while
brazing. Braze the connections and cool o quickly. Keep solenoid energized. Connect refrigerant
cylinder; add a small amount of 134a to high and low sides, then connect the Nitrogen cylinder and
start pressurization. On all series except the Mini series, this is a good time to check and verify the
low ambient control setting and function. Remove one wire from the Johnson pressure control and
connect an ohmmeter to its two terminals. With pressure below 100 psi, the meter should read open
circuit. Slowly increase pressure to 170 psi at which pressure the controller should make and the me-
ter read continuity.
After leak testing, slowly reduce pressure to 100 psi and at that pressure the ohmmeter should read
an open circuit, and at which pressure the condenser fan would stop. Continue pressure build up to
200 psi. Check to see if there is a noticeable pressure drop, if so look for and x leak. With pressure at
200 psi, check for leaks with a refrigerant leak detector and/or soap bubbles. Conrm pressure holds
at 200 psi for 30 minutes. If not check again for leaks and repair, perform another leak test. When it is
conrmed there are no leaks, slowly reduce pressure to check low ambient control then bleed o the
remaining pressure. Conrm that these procedures have been followed and there are no refrigerant
leaks.
Procedures followed:
Evacuation: Connect evacuation type four valve gauge manifold to high and low pressure service
valve ports on the condensing unit with the valve stems mid seated as when leak testing. Install
service caps on valves and tighten. Energize the liquid line solenoid valve. Make sure there is fresh oil
in the vacuum pump. Connect a micron gauge directly to the pump, blank o and start the pump to
verify the pump is capable of a 200 micron vacuum and the gauge is capable of reading that vacuum.
Next, connect the micron gauge to the access valve installed in the suction line at the evaporator,
remove the Schrader valve depressors from the gauge hoses to reduce restriction and connect to the
suction and liquid line service valve service ports on the condensing unit. Connect the pump to the
3/8” hose on the manifold set, start the pump and run until the micron gauge reads 200 microns. Con-
rm evacuation is complete and enter the micron gauge reading.
Micron gauge reading _________
When 200 micron evacuation is achieved, break the vacuum with R 134a and add more to pressur-
ize to a few psi positive pressure. Remove vacuum pump and micron gauge and install a spare low
pressure gauge to the access valve at the evaporator. With the power o to the condensing unit, place
refrigerant cylinder on a digital scale and admit liquid refrigerant to the system through the high
pressure side, (through the liquid line service valve) until the refrigerant stops owing or about three
pounds have been added. Shut o refrigerant ow to system.
Check thermostat setting and temperature of cellar or bottle that the probe is sensing. Set the con-
troller low enough for continued running of 30 minutes or more. Turn on power to condensing unit.
Compressor should start if suction pressure is above 6 psi. If system pumps down and compressor
shuts o, set 5 minute time delay relay time to lowest setting to avoid waiting. Add refrigerant to low
side, suction service valve port. When compressor starts, observe sight glass. If bubbles are pres-
ent, slowly add more refrigerant, in vapor form to the low side. Suction and head pressures should
increase as sight glass clears. Check superheat during charging process. If superheat drops to 4 or 5
degrees and sight glass still has bubbles, let run until wine cellar temperature drops and approaches
55 degrees.
Procedures followed: