Carrier 69NT40-561-300, Operation And Service Manual

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T-365 7–4
Automatic Pump Down:
To perform an Automatic Pump Down using Cd59 Pump Down Logic, refer to Table 4–3 Controller Function
Codes.
Manual Pump Down:
1. Attach manifold gauge set to the compressor suction and discharge service valves. Refer to paragraph 6.2.
2. Start the unit and run in the frozen mode (controller set below -10C (14F) for 10 to 15 minutes.
3. Check function code Cd21 (refer to Section 4.2.2 ). The economizer solenoid valve should be open. If not,
continue to run until the valve opens.
4. Frontseat the liquid line service valve. Place Start-Stop switch in the OFF position when the suction reaches
a positive pressure of 0.1 bar (1.4 psig).
5. Frontseat the suction and discharge service valves. The refrigerant will be trapped between the compressor
discharge service valves and the liquid line valve.
6. Before opening up any part of the system, a slight positive pressure should be indicated on the pressure
gauge. Remove power from the unit before opening any part of the system. If a vacuum is indicated, emit
refrigerant by cracking the liquid line valve momentarily to build up a slight positive pressure.
7. When opening up the refrigerant system, certain parts may frost. Allow the part to warm to ambient tempera-
ture before dismantling. This avoids internal condensation which puts moisture in the system.
8. After repairs have been made, be sure to perform a refrigerant leak check (refer to Section 7.5 ), and evacu-
ate and dehydrate the low side (refer to Section 7.6.1 ).
9. Check refrigerant charge (refer to Section 7.7 ).
7.5 REFRIGERANT LEAK CHECKING
WARNING
!
EXPLOSION HAZARD Failure to follow this WARNING can result in death, serious personal
injury and / or property damage.
Never use air or gas mixtures containing oxygen (O2) for leak testing or operating the product.
Charge only with R-134a: Refrigerant must conform to AHRI Standard 700 specification.
1. The recommended procedure for finding leaks in a system is with a R-134a electronic leak detector. Testing
joints with soapsuds is satisfactory only for locating large leaks.
2. If the system is without refrigerant, charge the system with refrigerant 134a to build up pressure between 2.1
to 3.5 bar (30.5 to 50.8 psig). To ensure complete pressurization of the system, refrigerant should be
charged at the compressor suction valve and the liquid line service valve. Remove refrigerant cylinder and
leak-check all connections.
NOTICE
Only refrigerant 134a should be used to pressurize the system. Any other gas or vapor will
contaminate the system, which will require additional purging and evacuation of the system.
3. If required, remove refrigerant using a refrigerant recovery system and repair any leaks. Check for leaks.
4. Evacuate and dehydrate the unit. (Refer to Section 7.6 .)
5. Charge unit per Section 7.7.1 .