Carrier 38MGR Series Service Manual

Carrier 38MGR Series Service Manual Manual pdf 27 page image

38MGR-04SM Specifications subject to change without notice. 27High Condenser Coil Temperature ProtectionFig. 30 — High Condenser Coil TemperatureProtectionOutdoor Unit Anti-Freezing ProtectionWhen T2<39°F (4°C) for 250 seconds or T2< 32°F (0°C), the indoorunit capacity demand is zero and resumes the normal operation whenT2>46.4°F (8°C) and the protection time is no less than three minutes.Oil ReturnRules for Operation:1. If the compressor frequency remains lower than the frequency setfor the setting time, the unit raises the frequency to the frequencyset for the setting time and then resumes the former frequency.2. The EXV continues at 300p while the indoor units maintain theiroperation. If the outdoor ambient temperature is higher than the setfrequency during the oil return, the unit stops the oil return process.Low Outdoor Ambient Temperature ProtectionWhen the compressor is off and T4 is lower than -31°F (-35°C) for tenseconds, the unit stops and displays “LP.”When the compressor is on and T4 remains lower than -40°F (-40°C)for ten seconds, the unit stops and displays “LP.”When T4 is no lower than -25.6°F(-32°C) for ten seconds, the unitexits protection.Controls and FunctionsCapacity Request CalculationCooling ModeFig. 31 — Cooling ModeTable 25 — Cooling ModeTable 26 — Cooling ModeNOTE: The final result is an integer.Use Table 27 and the final capacity request to confirm the operatingfrequency.Table 27 — Cooling ModeThe maximum running frequency is adjusted according to the outdoorambient temperature.Fig. 32 — Maximum Running FrequencyT3ResumeOffDecreaseHoldT1 Ts311eca 4202301fdbCAPACITY AREA a b c d e fNORM CODE (N) 3 2 1.5 1 0.5 0MODEL 9K 12K 18K 24KHP 1.0 1.2 1.5 2.5Frequency(Hz) 0 COOL_F1 COOL_F2 ...... COOL_F24 COOL_F25AmendatoryCapacityDemand 0 1 2 ...... 24 25T4FREMAXC0