Carrier 40MAQ Series Service Manual

Also see for 38MAQ Series: Owner's manual Product data Owner's manual Owner's manual

Carrier 40MAQ Series Service Manual Manual pdf 26 page image

26Compressor Operation in Cooling Mode:In cooling mode, the maximum operation frequency (Fmax) of thecompressor, after it starts running, depends on the outdoor ambienttemperature (T4).Once the system starts running, the compressor will run at the Fmaxfrequency for 7 minutes at a specific T4. During this time, thefrequency limitation is active, therefore the compressor will continuerunning even if the set point condition is satisfied. The compressorrunning frequency will then be controlled based on the differencebetween the room temperature and the temperature set point (T1- Ts).Outdoor Fan Operation in Cooling Mode:When in cooling mode, the outdoor fan motor cycles based on theoutdoor ambient temperature as shown below:7268HighLow°F°FFig. 27 – Outdoor Fan Motor CyclesIndoor Fan Operation in Cooling Mode:When in cooling mode, the indoor fan runs continuously either atthe chosen set speed (high, medium, or low), or in Auto mode,where the speed is determined by the microprocessor based on thedifference between the room temperature and the temperature setpoint as shown below:43HighLow1Medium1.5Fig. 28 – Indoor Fan OperationHEATING MODEIn this mode, the system heats the room air with the indoor fanrunning at either the selected speed or on Auto. As in the coolingmode, the indoor fan will run continuously unless interrupted bythe cold blow algorithm. This algorithm will not allow the fan torun if the indoor coil temperature drops below a preset value.Defrost is controlled by the on- board microprocessor.Compressor Operation in Heating ModeIn heating mode, the maximum operation frequency (Fmax) of thecompressor, after it starts running, depends on the outdoor ambienttemperature (T4).Once the system starts running, the compressor will run at theFmax frequency for 7 minutes at a specific outdoor ambienttemperature (T4). During this time, the frequency limitation isactive, therefore the compressor will continue running even if theset point condition is satisfied. The compressor running frequencywill then be controlled based on the difference between the roomtemperature, the temperature set point, and a temperature differencethat takes a default value of 32_F (T1- Ts- ΔT).Outdoor Fan Operation in Heating ModeWhen in heating mode, the outdoor fan motor cycles based on theoutdoor ambient temperature as shown below:6359LowHigh°FFig. 29 – Indoor Fan Motor CyclesIndoor Fan Operation in Heating ModeIn heating mode, the indoor fan runs depending on the evaporatorcoil temperature (T2).If the set point conditions are satisfied and the compressor stops,the indoor fan will be forced to run for two minutes with breeze.During this period, the anti- cold- wind is disabled.If the machine is running at the rated capacity test mode, the indoorfan will run at the rated speed and the anti- cold- wind function isdisabled.Auto Mode in Heating ModeIn heating mode, when the fan speed is set to Auto, the fan will runat a speed determined by the microprocessor based on thedifference between the room temperature and the temperature setpoint as shown below:2.52HighLow1Medium1.5Fig. 30 – Auto Mode