MAKE PIPING CONNECTIONS — Piping connections at the 38AUQ unit are ball valves with stub tube extensions. Do not open the unit service valves until all interconnecting tube brazing as been completed.
The stub tube connections include ¼-in SAE service fittings with Schrader valve cores (see Fig. 7). Before making any brazed connections to the unit service valves, remove both Schrader valve caps and cores and save for re-installation. Con- nect a source for nitrogen to one of these service fittings during tube brazing to prevent the formation of copper oxides inside the tubes at brazed joints.
| | Field Service |
| Factory | Access Port |
| (Schrader core) |
| High-Flow |
| |
| Access Port | |
| Service Valve | |
| with Stem Cap | Sweat |
| | Connection |
Fig. 7 — Typical Piping Connection Assembly
When connecting the field tubing to the 38AUQ service valves, wrap the valves in wet rags to prevent overheating
Pressure-test all joints from outdoor unit connections over to the indoor coil, using nitrogen as pressure and with soap-and- bubbles.
When pressure-testing is completed, remove the nitrogen source at the outdoor unit service valves and re-install the two Schrader valve cores. Torque the cores to 2-3 in-lbs (23-34 N-cm).
Where vapor line is exposed to outdoor air, line must be insulated. See Table 7 for insulation requirements.
EVACUATION/DEHYDRATION — Evacuate and dehydrate the connected refrigeration system(s) (excluding the 38AUQ unit) to 500 microns using a two-stage vacuum pump attached to the service ports outside the 38AUQ service valves, follow- ing description in GTAC II, Module 4, System Dehydration.
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal injury, death and/or equipment damage.
Puron® (R-410A) refrigerant systems operate at higher pressures than standard R-22 systems. Do not use R-22 service equipment or components on Puron refrigerant equipment.
IMPORTANT: Charge in Cooling mode only!
PRELIMINARY CHARGE — Before starting the unit, charge R-410A liquid refrigerant into the high side of each 38AUQ circuit through the liquid service valve(s). The amount of refrigerant added must be at least 80% of the operating charge listed in Table 2 for LINEAR line length LESS the factory charge quantity (if factory shipping charge has not been removed). See the following example.
Allow high and low side pressures to equalize. If pressures do not equalize readily, charge R-410A vapor (using special service manifold with expansion device) into the suction line service port for the low side of system to assure charge in the evaporator. Refer to GTAC II, Module 5, Charging, Recover, Recycling, and Reclamation for liquid charging procedures.
Example:
38AUQ*08
60-ft (18.3 m) linear line length Equivalent line length 90-ft (27.4 m) Liquid Lift: 20-ft (6.1 m)
Select line sizes from Table 2 (38AUQ): Liquid 1/2 in
Suction 1-1/8in.
Charge 23.0 lbs (at 75-ft linear length)
80% of Operating Charge:
0.80 x 23.0 = 17.6 lbs
Factory Shipping Charge: 12 lbs
Field-charge quantity: 17.6 lbs –12.0 lbs = 5.6 lbs
For linear line lengths longer than 100 ft (30.5 m), contact your local Carrier representative for system charge value.
Step 6 — Install Accessories
Accessories requiring modifications to unit wiring should be completed now. These accessories may include Winter Start controls, Low Ambient controls, phase monitor, Compressor LOCout. Refer to the instructions shipped with the accessory.
Step 7 — Complete Electrical Connections
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Do not use gas piping as an electrical ground. Unit cabinet must have an uninterrupted, unbroken electrical ground to minimize the possibility of personal injury if an electrical fault should occur. This ground may consist of electrical wire connected to unit ground lug in control compartment, or conduit approved for electrical ground when installed in accordance with NEC (National Electrical Code); ANSI/ NFPA 70, latest edition (in Canada, Canadian Electrical Code CSA [Canadian Standards Association] C22.1), and local electrical codes.
NOTE: Check all factory and field electrical connections for tightness. Field-supplied wiring shall conform with the limitations of 63°F (33°C) rise.
Field Power Supply —
If equipped with optional Powered Convenience Outlet: The power source leads to the convenience outlet's transformer pri- mary are not factory connected. Installer must connect these leads according to required operation of the convenience outlet. If an always-energized convenience outlet operation is desired, connect the source leads to the line side of the unit-mounted disconnect. (Check with local codes to ensure this method is acceptable in your area.) If a de-energize via unit disconnect switch operation of the convenience outlet is desired, connect the source leads to the load side of the unit disconnect. On a unit without a unit-mounted disconnect, connect the source leads to compressor contactor C and indoor fan contactor IFC pressure lugs with unit field power leads.
All units except 208/230-v units are factory wired for the volt- age shown on the nameplate. If the 208/230-v unit is to be con- nected to a 208-v power supply, the control transformer must be rewired by moving the black wire with the 1/4-in. female spade connector from the 230-v connection and moving it to the 208-v 1/4-in. male terminal on the primary side of the trans- former. Refer to unit label diagram for additional information.
