Midea M-Thermal Series - Page 64

  M‐ThermalSplit 
20190963
Procedure

P1 


Highpressureswitchconnectionor
pressuresensorconnectiononoutdoor
unitmainPCBisloose
1

Yes
Ensurethepressureswitchisconnected
properly
No

Pressuresensorhasshort‐circuitedor
failed
2

Yes
Replacethepressuresensor
No

Thehighpressuresideisblocked,caused
bycrushedorbentpipeorblockedEXV
3
Yes
Inspectthesystemandfixtheerror
No

Theheatexchangeispoor
4

Yes
Inspectthesystemandfixtheerror
No

Thewaterflowrateisnotsufficientin
coolingmode
5

Yes
Inspectthewatersystemandfixthe
error
No

ReplaceoutdoormainPCB  

Notes: 
1. HighpressureswitchconnectionisportCN13onthemaincontrolboardofoutdoorunit(labeled10inFigure4‐2.2inPart4,2.3"MainPCBsforRefrigerant
System,InverterModule".PressuresensorconnectinisportCN4onthemaincontrolboardofoutdoorunit(labeled15inFigure4‐2.2inPart4,2.3"Main
PCBsforRefrigerantSystem,InverterModule"
2. Measuretheresistanceamongthethreeterminalsofthepressuresensor.IftheresistanceisoftheorderofmegaOhmsorinfinite,thepressuresensor
hasfailed.
3. Highpressuresideblockagecausesdischargetemperaturetobehigherthannormal,dischargepressuretobehigherthannormalandsuctionpressureto
belowerthannormal.
4. Inheatingmodecheckwatersideheatexchanger,waterpiping,circulatorpumpsandwaterflowswitchfordirt/blockages.Incoolingmodecheckairside
heatexchanger,fan(s)andairoutletsfordirt/blockages.
5. Check waterpressureon themanometer.Ifthewaterpressureisnot>1bar,waterflowisinsufficient.RefertoFigure2‐1.6and2‐1.7inPart2,1.2
“HydronicBoxLayout”.

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