Carrier 40MVQ, 40MVC, 38MVQ, 38MVC service manual Auto Fan, Defrost

Page 23

Auto Fan

When the fan speed is set to Auto, the fan will run at either the medium or low speed based on the difference between the room temperature and the set point temperature as shown below:

Low. Speed

Room te

m

p. down

 

 

 

 

 

 

 

 

 

 

 

 

 

Room

te

mp. up

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Med. Speed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Defrost

Defrost on heat pump units is controlled by the microprocessor and is initiated if either of the following conditions occur:

1.The outdoor coil temperature is lower than 32_F (0_C) for more than 40 minutes and during that period, the coil temperature is continuously lower than 26.6_F (-3_C) for 3 minutes.

2.If the first condition does not occur within 90 minutes of termination of the last defrost cycle.

The defrost cycle will terminate 10 minutes after initiation or when the coil temperature reaches 68_F (20_C). At the end of the

T = Room Temperature Ts = Set Point Temperature

0 3.6°FT-Ts

A08112

Defrost cycle the timer resets automatically.

The cycles of defrost algorithm are shown below:

Defrost 10 or 6 minutes

Fig. 28 – Auto Fan - Heating Mode

Manual Indoor Fan

The indoor fan will run continuously in heating at the set fan speed (even if the compressor cycles off) unless the indoor coil temperature begins to drop. When the coil temperature drops to the TE3 limit, the 18k and 24k unit indoor fan switches to low speed. On the 9k and 12k unit the indoor fan switches to ultra low speed. When the coil temperature drops to the TE4 limit, the indoor fan on all systems shuts off to prevent cold blow as shown below. The cold blow algorithm also applies to the auto fan setting.

Compressor

4-way valve

Outdoor fan

Indoor fan

On

Off

5s

25s

2s

38/40MVC, MVQ

 

 

 

 

 

 

 

 

 

 

 

Set fan speed

 

 

 

 

 

 

 

 

 

 

 

 

 

Low Speed /

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ultra Low Speed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T tem

p.

down

 

 

 

 

 

 

 

 

 

T tem

p. up

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(Coil temp.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fan off

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TE4

TE1

TE3 TE2

 

T

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A08111

 

 

 

 

Fig. 29 – Manual Indoor Fan - Heating Mode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Parameter

 

 

Indoor Coil Temperature ˚F (˚C)

 

 

40MVQ

 

 

40MVQ

 

 

40MVQ

 

 

 

40MVQ

 

 

 

 

 

 

 

009---1

 

 

 

012---1

 

018---3

 

024---3

 

 

TE1

88 (31)

 

 

 

88 (31)

 

77 (25)

 

82 (28)

 

 

TE2

93 (34)

 

 

 

91 (33)

 

90 (32)

 

93 (34)

 

 

TE3

86 (30)

 

 

 

81 (27)

 

86 (30)

 

90 (32)

 

 

TE4

72 (22)

 

 

 

68 (20)

 

68 (20)

 

75 (24)

 

Sleep Mode

When in heating mode additional energy savings can be realized by selecting the Sleep setting. When the Sleep setting is selected, the temperature set point is adjusted automatically as shown below:

Set Point

 

 

1.8ºF

 

 

 

1.8ºF

 

1

2

Time (hour)

A08110

Fig. 30 – Sleep Mode - Heating

The unit will shut off 7 hours after the Sleep mode is selected.

10s

A08114

Fig. 31 – Defrost Cycle

Auto Mode

When the Auto setting is selected, the microprocessor looks at the difference between the room temperature (T) and the set point (TS). The algorithm determines which mode the unit will run in as shown below:

Heating (fan only in cooling)

Fan only

Cooling

 

 

 

-1.8°F 3.6°F T-TS

A08115

Fig. 32 – Auto Mode

When the unit shifts modes, it will remain in that mode for at least 15 minutes while the algorithm ignores the difference between T and TS. This ensures that the unit cannot change modes too frequently.

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Contents Introduction 38MVC/40MVC 38MVQ/40MVQIndoor Unit Model Number NomenclatureStandard Features and Accessories Coil Specifications Cooling only UnitsSystem Model Number Outdoor Specifications Heat Pump UnitsService Valve Locations Clearances Indoor Electrical Data 53MVC/MVQ System Operating Envelope ChartSystem Operating Envelope Connection Diagrams Connection DiagramsWiring Diagram 38MVC009----1 W/ 40MVC009----1 Wiring DiagramsWiring Diagram 38MVC012----1 W/ 40MVC012----1 Wiring Diagram 38MVC012----3 W/ 40MVC012----3 Wiring Diagram 38MVC018----3 W/ 40MVC018----3 Wiring Diagram 38MVQ009----1 W/ 40MVQ009----1 Wiring Diagram 38MVQ012----1 W/ 40MVQ012----1 Wiring Diagram 38MVQ012----3 W/ 40MVQ012----3 Cooling Refrigeration Cycle DiagramRefrigerant Charge Refrigerant LinesGeneral refrigerant line sizing System Evacuation and Charging Using Vacuum Pump Compressor Overcurrent Protection Minute Time Delay Control System System SafetiesIndoor Coil Freeze Protection Condenser High Temperature ProtectionIndoor High Temperature Protection Sequence of OperationModes of Operation Defrost Auto FanForced Cooling Operation Dry Dehumidification ModeManual Operation Recommended Steps TroubleshootingDiagnostic Hierarchy Required ToolsYes Chart 1 Indoor FAN Speed OUT of ControlChart 2 Temperature Sensor Chart 3 Compressor Overcurrent Protection Chart 4 Indoor Unit Communication Error Size 9K and 12K Chart 5 Outdoor Unit Protects Chart 6 Indoor Unit Communication Error Size 18K and 24K Chart 7 Unit not RUNNING, no Diagnostic Code Chart 8 Unit not Running Optimally Chart 9 Unit not Running Optimally HP in Heating Chart 10 Compressor Chart 11 Outdoor Motor Chart 13 Receiver Board Chart 12 Reversing ValveAppendix Appendix Table of Contents Description Number38MVQ009---1/38MVQ012--- --- ---1 Control Board 38MVC009--- --- ---1/38MVC012--- --- ---1 Control BoardInput or Output Value 40MVC009--- --- ---1/40MVC012--- --- ---1 Control Board40MVQ012--- --- ---3 Control Board 38MVC012--- --- ---3 Control Board40MVC012--- --- ---3 Control Board 38MVQ012--- --- ---3 Control BoardControl Board 38MVC018--- --- ---3 Control BoardTemp. ˚F/˚C Resistance KΩ A6 Characteristics of Temperature Sensor18K & 24K Units 9K & 12K UnitsCatalog No.38---40MV---1SM
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40MVQ, 40MVC, 38MVQ, 38MVC specifications

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