Mitsubishi Electric MS-GD-VB Service Manual Download Page 39

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3-11. HEAT OPERATION

2. High pressure protection

In HEAT operation the indoor coil thermistor detects the temperature of the indoor heat exchanger. The compressor opera-
tional frequency is controlled to prevent the condensing pressure from increasing excessively.

1. Thermostat control

Thermostat turns ON or OFF by difference between room temperature and set temperature.

ON less than 1°C
OFF 1°C or more

0.7°C

1°C

Thermostat

Room temperature minus
set temperature (Initial)

Room temperature minus
set temperature (During operation)

Summary of Contents for MS-GD-VB

Page 1: ... C VA E have been added Please void OBT17 REVISED EDITION F CONFIDENTIAL FOR INTERNAL USE ONLY Models MSC GE VB E MS GD VB E MU GD VB E MS GE VB E MU GE VB E MSH GD VB E MUH GD VB E MSH GE VB E MUH GE VB E MSZ GC VA E MUZ GC VA H E MSZ HC VA B E MUZ HC VA B E MSZ CHC VA E MSZ FD VA S E MUZ FD VA H BH E MSZ GE VA E MUZ GE VA H E MSZ CGE VA E MSZ SF VA E MSZ EF VEW E MUZ EF VE E MSZ EF VEB E MUZ EF ...

Page 2: ...R CONTROL 8 1 5 AUTO VANE OPERATION 8 1 6 EXPANSION VALVE CONTROL LEV CONTROL 10 Revision C MSZ FD50VA E MSZ GE VA E MSZ CHC VA E and MSZ CGE VA E have been added Revision D MSC GE VB E MS GE VB E MSH GE VB E MUZ FD50VA E MSZ GE42 50VA E and MSZ CGE42 50VA E have been added Revision E MSZ GE60 71VA E MUZ GE60 71VA E MSZ SF15 20VA E MXZ 3B54VA E MXZ 3B68VA E MXZ 4B71VA E MXZ 4B80VA E and MXZ 5B100V...

Page 3: ...CONTROL 17 2 9 OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT 21 2 10 PRE HEAT CONTROL 21 2 11 EXPANSION VALVE CONTROL LEV CONTROL 22 2 12 STANDBY POWER CONTROL 23 NOTE As for the MXZ A type models or MU MUH GA type models refer to the appropriate service technical guide as well as this service technical guide 3 MXZ MICROPROCESSOR CONTROL 24 Outdoor unit models MXZ 2B30VA MXZ 3B68VA MXZ 3C54VA MXZ ...

Page 4: ... C or more the compressor is turned OFF After 3 minutes since the compressor has been turned OFF if the temperature of discharge temperature thermistor becomes 100 C or less the compressor is turned ON 4 Outdoor fan speed control MU GD80VB MUH GD80VB Outdoor fan speed control is as follows Outdoor fan speed High or Med Indoor fan speed 20 C 22 C Low 30 C 33 C High Temperature of ambient temperatur...

Page 5: ...35 30 25 20 15 10 10 15 20 25 30 35 Set temperature Initial room temperature Set temperature and initial room temperature in DRY mode Thermostat Indoor fan Outdoor fan Compressor ON 8 minutes 3 minutes ON OFF OFF OFF OFF OFF OFF OFF OFF ON ON ON ON ON ON Operation time chart Example When the room temperature is 23 C or over 4 Coil frost prevention The operation is the same as coil frost prevention...

Page 6: ...r prevention control When the compressor is not operating MSC GE20 25 35VB If the temperature of indoor coil thermistor RT12 is 0 C or less the fan stops If the temperature of indoor coil thermistor RT12 is more than 0 C the fan operates at Very Low When the compressor is operating If the temperature of RT12 is 22 C or more the fan operates at set speed If the temperature of RT12 is less than 22 C...

Page 7: ...board with detection by the defrost thermistor 1 Starting conditions of defrost When all conditions of a c are satisfied the defrosting operation starts a Under the heat operation the compressor cumulative operation time exceeds 40 minutes without the defrosting opera tion working b The defrost thermistor reads 3 C or less c After releasing the high pressure protection 4 minutes and 10 seconds hav...

Page 8: ...rent to the fan motor is shut off 3 minutes later the electric current is applied to the fan motor again During the fan motor lock up the OPERATION INDICATOR lamp flashes ON and OFF to show the fan motor abnormality 1 5 AUTO VANE OPERATION MSC MSH 1 Horizontal vane 1 Cold air prevention in HEAT operation When any of the following conditions occur in HEAT operation the vane angle changes to Angle 1...

Page 9: ...ing operation of ECONO COOL operation mode the initial airflow direction is adjusted to Horizontal According to the temperature of indoor coil thermistor at starting of this operation next downward blow time is decided Then when the downward blow has been finished next horizontal blow time is decided For initial 10 minutes the swing operation is performed in table G H for quick cooling Also after ...

Page 10: ...on mode and outer temperature con ditions Approximately 2 to 13 minutes for 11 minutes after compressor has started Opening is set by standard opening Standard opening is set according to each operation mode and outer temperature conditions 13 minutes after compressor has started LEV opening is corrected every 2 minutes so that discharge temperature becomes the target discharge temperature When th...

Page 11: ...ee of expansion valve is corrected according to the discharge temperature But in this mode it is fixed to the value corresponding to the operation frequency of compressor 3 Dew drop prevention When the ambient temperature thermistor reads 20 C or less as coil frost or dew drop from indoor unit may occur the compressor turns OFF with the outdoor fan ON for prevention of it 4 Outdoor temperature det...

Page 12: ...peed Room temperature minus set temperature During operation Room temperature minus set temperature Initial Between 1 and 1 75 C Less than 1 C 1 75 C or more 2 2 DRY OPERATION Set temperature is as shown on the right chart The system for dry operation uses the same refrigerant circuit as the cooling circuit The compressor and the indoor fan are controlled by the room tem perature By such controls ...

Page 13: ...changes as follows to blow out warm air gradually Gradation of fan speed in initial Time condition Indoor fan speed Less than 2 minutes Low 2 to 4 minutes Med More than 4 minutes High or Super high The upper limit of the fan speed in MANUAL is the set speed When the temperature of indoor coil thermistor has been 40 C or more or when the set speed has been changed this control is released and the f...

Page 14: ...ing conditions When all of the following conditions a d are satisfied defrost heater turns ON to prevent ice from foaming on the base of outdoor unit a HEAT mode is selected b The ambient temperature thermistor reads 5 C or less for 5 minutes continuously NOTE 1 c The defrost thermistor reads 1 C or less for 5 minutes continuously d Outdoor fan motor is turned ON 2 Releasing conditions When any of...

Page 15: ...the selected operation mode when the operation mode changes over they change to the exclusive ones 2 5 OUTDOOR FAN MOTOR CONTROL Fan speed is switched according to the compressor frequency 2 6 AUTO VANE OPERATION 1 Horizontal vane 1 Cold air prevention in HEAT operation When any of the following conditions occur in HEAT operation the vane angle changes to horizontal position automati cally to prev...

Page 16: ...nditioner repeats the swing operation in various cycle as follows Temperature of indoor coil thermistor C Downward blow time second Horizontal blow time second A 15 or less 2 23 B 15 to 17 5 20 C 17 to 18 8 17 D 18 to 20 11 14 E 20 to 21 14 11 F 21 to 22 17 8 G 22 to 24 20 5 H More than 24 23 2 2 7 DRAIN PUMP FLOAT SENSOR CONTROL MLZ Drain pump motor OFF When ON timer is set or during multi system...

Page 17: ...RELAY SMOOTHING CAPACITOR CURRENT TRANSFORMER COMPRESSOR DIODE MODULE1 DIODE MODULE2 REACTOR P W V U N INTELLIGENT POWER MODULE U W MS 3 V BOOSTER CHOPPER CIRCUIT Function of main parts NAME FUNCTION INTELLIGENT POWER MODULE It supplies 3 phase AC power to compressor SMOOTHING CAPACITOR It stabilizes the DC voltage and supply it to INTELLIGENT POWER MOD ULE DIODE MODULE 1 It converts the AC voltag...

Page 18: ...thod with PAM which has been adopted this time places and utilizes BOOSTER CHOPPER CIRCUIT before rectifying AC voltage in the general passive meth od converter circuit As harmonic gets suppressed and the peak of waveform gets lower by adding BOOSTER CHOPPER CIR CUIT as mentioned above and by synchronizing the timing of switching with the zero cross point of waveform the input current waveform can...

Page 19: ...ENT POWER MODULE has a merit that can get the control circuit simplified and miniaturized 5 Elimination of electrical noise NOISE FILTER CIRCUIT which is formed by CMC COILS and capacitors placed on the noise filter P C board eliminates electrical noise of AC power that is supplied to main power supply circuit In short common mode noise is absorbed in this circuit Moreover normal mode noise is abs...

Page 20: ...tor accord ing to the polar direction of magnet embedded in the rotor so as to drive the motor efficiently Controlling 3 phase AC cur rent frequency also means controlling the timing to switch the polarity of stator Therefore the polar direction of rotor needs to be detected 2 8 3 Sine wave control In these air conditioners compressor equips brushless DC motor which does not have hall element In s...

Page 21: ...icted by the upper limit frequency after 0 5 1 hour as shown below for dew prevention It is rated frequency or less Maximum frequency 0 5 1 hour Upper limit frequency Rated frequency or less Time 2 10 PRE HEAT CONTROL 1 Outline Compressor is energized to improve the start up of compressor at a low outside temperature even when compressor is stopped 2 Pre heat control MUZ GC HC FD GE 30 minutes 1 h...

Page 22: ...minutes have passed since com pressor start up LEV opening degree is corrected to get target discharge tem perature of compressor For lower discharge temperature than target temperature LEV is corrected in closing direction For higher discharge temperature than target temperature LEV is corrected in opening direction It may take more than 30 minutes to reach target tempera ture depending on operat...

Page 23: ...7 60 60 65 62 70 67 75 74 75 81 75 MUZ GE60 49 42 53 49 59 58 64 67 69 75 74 83 MUZ GE71 55 46 61 56 66 66 72 75 77 83 81 86 MUZ EF25 52 43 58 50 65 55 67 59 70 65 71 69 MUZ EF35 53 43 60 51 64 58 67 59 72 69 76 75 MUZ EF42 49 43 55 51 61 59 67 69 72 75 76 80 MUZ EF50 49 42 53 49 59 58 64 67 69 75 74 83 F E D C B A Target discharge temperature 30 50 70 Operational frequency of the compressor Hz 90...

Page 24: ...rcuit the power is turned ON RELAY It keeps the RESISTOR which restricts rush current short circuited while the compressor is operating MXZ 2B30VA MXZ 2B40VA MXZ 2B52VA POWER SUPPLY NOISE FILTER CIRCUIT RESISTOR SWITCHING POWER TRANSISTOR RELAY SMOOTHING CAPACITOR CURRENT TRANSFORMER COMPRESSOR DIODE MODULE1 DIODE MODULE2 REACTOR P W V U N INTELLIGENT POWER MODULE U W MS 3 V BOOSTER CHOPPER CIRCUI...

Page 25: ... down The simple partial switching method with PAM which has been adopted this time places and utilizes BOOSTER CHOPPER CIRCUIT before rectifying AC voltage in the general passive method converter circuit As har monic gets suppressed and the peak of waveform gets lower by adding BOOSTER CHOPPER CIRCUIT as mentioned above and by syn chronizing the timing of switching with the zero cross point of wa...

Page 26: ...ELLIGENT POWER MODULE INTELLIGENT POWER MODULE has a merit to make the control circuit simplified and miniaturized 5 Elimination of electrical noise NOISE FILTER CIRCUIT which is formed by CMC COILS NMC COILS and capacitors placed on P C board eliminates electrical noise of AC power that is supplied to main power supply circuit This circuit also prevents electrical noise generated in the inverter ...

Page 27: ...e DC voltage to 350V DC voltage to which AC has been rectified by process is stabilized by SMOOTHING CAPACITOR and supplied to POWER TRANSISTOR BRIDGE The DC Bus voltage which has been stabilized in process is converted to 3 phase AC by POWER TRANSISTOR BRIDGE and supplied to COMPRESSOR CURRENT TRANSFORMER which is placed in the power supply circuit to COMPRESSOR is used to measure the value of ph...

Page 28: ... indoor unit operates 59 pules MXZ 2B 140 pulse MXZ 3B 4B 5B 3C 4C 5C 6C When the outdoor unit stops When the other indoor unit stops or thermo OFF Maintain LEV opening before stop 500 pulse in 15 minutes Thermostat ON in HEAT mode LEV opening for each indoor unit is determined by adding adjustment according to the number of operating unit and the capacity class to standard opening based on the op...

Page 29: ...de5 6 Code7 8 2 COOL 10 20 30 60 HEAT 5 10 15 100 The standard opening is on the straight line which connects an each standard point in the section where divided into seven according to the operation frequency of compressor as shown in the figure below LEV opening is controlled in proportion to the operation frequency NOTE Opening is adjusted at the standard opening according to the indoor unit co...

Page 30: ...operation number 2 3 4 COOL 0 0 0 HEAT 16 60 125 MXZ 4B80VA MXZ 5B100VA MXZ 4C80VA MXZ 5C100VA Exclusive LEV Standard opening pulse LEV Opening code 1 2 3 4 5 6 7 8 9 10 COOL 126 130 134 138 150 160 170 180 190 200 HEAT 248 248 258 266 274 280 286 292 300 306 Difference in capacity Difference in operation number Code 1 2 Code 3 4 Code 5 6 Code 7 8 Code 9 10 Code 11 12 Code 13 14 Code15orabove 2 3 ...

Page 31: ... 23 56 60 57 51 24 38 59 61 63 58 39 54 59 64 69 64 55 69 60 67 75 71 70 85 61 67 80 77 86 100 62 69 86 83 101 Maximum 63 70 90 90 MXZ 6C120VA Exclusive LEV Standard opening pulse LEV Opening code 1 2 3 4 5 6 7 8 9 10 COOL 204 204 204 216 216 216 216 216 216 216 HEAT 130 130 130 140 140 150 150 160 160 170 Difference in capacity Difference in operation number Code 1 2 Code 3 4 Code 5 6 Code 7 8 Co...

Page 32: ... 80 85 88 68 99 Maximum 80 87 88 84 80 85 88 70 MXZ 3B54VA MXZ 3B68VA MXZ 4B71VA MXZ 3C54VA MXZ 3C68VA MXZ 4C71VA Operation frequency of compressor Hz Target discharge temperature C COOL HEAT 1 unit 2 units 3 units 4 units MXZ 4B71VA MXZ 4C71VA 1 unit 2 units 3 units 4 units MXZ 4B71VA MXZ 4C71VA Minimum 23 35 58 62 62 50 50 50 50 24 38 40 60 65 65 56 50 55 55 39 54 49 65 70 70 60 56 60 60 55 69 5...

Page 33: ...1 1 Target discharge temperature 5 to Target discharge temperature 10 3 2 Target discharge temperature 10 or less 4 3 MXZ 4B80VA MXZ 5B100VA MXZ 4C80VA MXZ 5C100VA Discharge temperature C LEV opening correction pulse COOL HEAT More than Target discharge temperature 12 4 6 Target discharge temperature 12 to Target discharge temperature 5 2 2 Target discharge temperature 5 to Target discharge temper...

Page 34: ... 100 17 34 101 80 58 112 100 3 3 40 101 58 58 112 100 3 3 OPERATIONAL FREQUENCY RANGE MXZ 2B30VA Number of operating unit Capacity code COOL Hz DRY Hz HEAT Hz Min Max Min Max defrost 1 1 2 40 64 40 35 97 97 3 4 40 64 44 35 97 97 2 4 55 97 78 35 97 97 5 7 55 97 78 35 97 97 8 55 97 86 35 97 97 MXZ 2B40VA Number of operating unit Capacity code COOL Hz DRY Hz HEAT Hz Min Max Min Max defrost 1 1 2 30 5...

Page 35: ... 58 18 22 70 70 70 7 15 58 18 22 70 70 70 9 15 68 31 22 80 80 80 10 18 68 31 22 80 80 80 12 18 68 42 22 90 90 80 13 18 79 42 22 90 90 80 2 4 24 72 30 35 80 80 80 5 7 24 80 30 35 80 80 80 8 10 24 80 31 35 80 80 80 11 13 24 90 31 35 94 94 80 14 16 24 90 31 35 94 94 80 17 24 90 52 35 94 94 80 3 3 42 90 42 39 94 105 80 4 4 53 94 53 52 94 120 80 5 5 53 94 53 52 94 120 80 MXZ 6C120VA Number of operating...

Page 36: ...e discharge tem perature thermistor 1 Compressor ON OFF When the temperature of the discharge temperature thermistor exceeds 116 C MXZ 2B 3B 4B 5B 3C 4C 5C 114 C MXZ 6C the control stops the compressor When the temperature of the discharge temperature thermistor is 80 C MXZ 2B40 2B52 3B 4B71 3C 4C71 100 C MXZ 2B30 4B80 5B 4C80 5C 6C or less the controls start the compressor 2 Compressor operation ...

Page 37: ...5 9 500 500 500 425 10 550 550 550 525 11 600 600 600 575 12 700 650 650 585 13 800 700 700 590 14 900 750 750 750 Frequency Hz Target condensing temperature ºC MXZ 2B30 40 52VA MXZ 3B54 68VA MXZ 4B71 80VA MXZ 5B100VA MXZ 3C54 68VA MXZ 4C71 80VA MXZ 5C100VA MXZ 6C120VA 24 31 35 38 42 25 34 33 37 37 41 35 44 35 39 37 41 45 54 37 41 37 41 55 64 37 41 37 41 65 37 41 37 41 Up Down Fan speed High Low C...

Page 38: ... temperature minus set temperature Initial Thermostat 3 8 PRE HEAT CONTROL The compressor is energized even while it is not operating This is to generate heat at the winding to improve the compressor s start up condition NOTE When the unit is started with the remote controller pre heat control is turned OFF Compressor uses 50 W when pre heat control is turned ON 1 Pre heat control is turned ON for...

Page 39: ... opera tional frequency is controlled to prevent the condensing pressure from increasing excessively 1 Thermostat control Thermostat turns ON or OFF by difference between room temperature and set temperature ON less than 1 C OFF 1 C or more 0 7 C 1 C Thermostat Room temperature minus set temperature Initial Room temperature minus set temperature During operation ...

Page 40: ...ed in Nov 2010 No OBT17 REVISED EDITION G Distributed in Jan 2010 No OBT17 REVISED EDITION F 5 Distributed in Oct 2009 No OBT17 REVISED EDITION E 6 Distributed in Dec 2008 No OBT17 REVISED EDITION D 6 Distributed in Aug 2008 No OBT17 REVISED EDITION C 5 Distributed in Apr 2008 No OBT17 REVISED EDITION B 7 Distributed in Aug 2007 No OBT17 REVISED EDITION A 7 Distributed in Feb 2007 No OBT17 7 Made ...

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