Carrier 42NQ009N Service Manual

Contents

FILE NO. SVM-1003619 --7-4. High-Temperature Limit Control 7-6. Defrost OperationThe microcontroller detects the indoor heat exchangerDurtemperature to pre ing the heating operv ation, the outdoor heatent pressure of a refreigerxchanger temperating cycleature goes dofrom increasing e wn and sometimes it isxcessivfrozelyen..In this caseThe compressor and outdoor f, the air conditioner stops the heatingan motor are controlledoperas shoation and starwn in Fig.ts the defrost oper7-4-1.ation to melt iceFig. 7-4-1.7-5.7-6-1.LoCondition to starw-Tt the defremperature Limit Controst operationolThe defrost operThe microcontroller detects the indoor heat eation starxchangerts whichetemperature to prevver beloent the indoor heat ewxchanger fromconditions are satisfied.freezing.(1)The compressor and outdoor fWhen the cuman motor are controlledulativas shoe compressor operwn in Fig.ating time is7-5-1longer than 40 or 90 minutes and differencebetwFig. 7-5-1een the indoor heat exchanger temperatureand the room temperature is less than thespecified value60.((This value is decided b°C)y the53microprocessor52.) (Control example is shown inFig. 7-6-1. In case of B or C, the defrost operationCompressorstartsOutdoor fan.)OFF(2)OFFWhen the current limit control or the highONtemperature limit control is perfONorOFFmed fONor total of90 minHeat exchangerutestemp..Fig. 7-6-1 (Indoor fan speed : M)7-6-2.5Defr(ost operation time control°C)2(1) The heating operation is performed for at least40 minCompressorutesOutdoor fan.ON(2)Less than 2The maximum defrost oper°C continuesating time is 6 minfor 5 minutesutesOFF.Heat exchangerThe defrost opertemperatureating time for the 4th cycle is10 minutes. (When the outdoor temperature isvery low, however, the defrost operating time is10 minutes.)Indoor heat exchanger temp- Room tempCumulativecompressoroperating timeDBCA