Heat Defrosting Control; Discharge Temperature Protection Control; Outdoor Fan Control - Mitsubishi Electric MS-A•WA Service Technical Manual

Split-type, air conditioners split-type, heat pump air conditioners
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3-4. HEAT DEFROSTING CONTROL

(1) Conditions to enter defrosting mode
1. When temperature of defrosting thermistor is 26.6˚F or less.
2. When specified non-defrosting time, is counted in the control p.c. board is satisfied.
(Total time of compressor operating)
Going to defrosting mode at both condition of 1 and 2.
(2) Defrosting operation
1. Compressor stops for 50 seconds, Indoor fan is off, Defrosting lamp lights.
2. 4-way valve reverses flow, Compressor operates by the frequency in heat defrosting control.
3. After compressor stops for 35 seconds, 4-way valve reverses flow, then defrosting finishes.
(3) Conditions to finish defrosting mode
1. When the defrosting thermistor temperature is 55.76˚F or more.
2. When it has spent 10 minutes for defrosting.
Defrosting finishes at condition of 1 or 2.

3-5. DISCHARGE TEMPERATURE PROTECTION CONTROL

This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge
temperature thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temperature thermistor exceeds 240.8˚F, the control stops the compressor.
When temperature of the discharge temperature thermistor is 176˚F or less, the controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temperature thermistor is expected to be higher than 240.8˚F, the control decreases 12Hz
from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 231.8˚F and less than 240.8˚F, the
control decreases 6Hz from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 219.2˚F and less than 231.8˚F, the
control is set at the current frequency.

3-6. OUTDOOR FAN CONTROL

Fan speed is switched according to the number of operating indoor unit and the compressor frequency.
Fan speed
Down
High
Low
Min.
Compressor frequency
<Relation between compressor frequency and fan speed.>
Mode
Fan speed
Up
COOL
Down
Up
HEAT
Down
Note
• When the indoor coil thermistor is 134.6˚F or more on HEAT operation, fan speed is fixed to Low speed.
Or, the indoor coil thermistor is 113˚F or less on HEAT operation, fan speed is back to normal.
HEAD OFFICE: TOKYO BLDG.,2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN
C C Copyright 2006 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in Apr. 2006. No. OBT16 7
Made in Japan
Up
Max.
Compressor frequency
40Hz
30Hz
40Hz
30Hz
New publication, effective Apr. 2006
Specifications subject to change without notice.

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