Mitsubishi Electric PUZ-A18NHA2 Service Manual page 57

10-7. HOW TO CHECK THE COMPONENTS
<Thermistor feature chart>
Low temperature thermistors
• Thermistor <Outdoor pipe> (TH3)
• Thermistor <Outdoor 2-phase pipe> (TH6)
• Thermistor <Outdoor> (TH7)
Thermistor R0 = 15k' ± 3%
B constant = 3480 ± 2%
1
=15exp{3480( 273+t – 273 )}
t (:): R
t
=15exp{3480( 273+(T– 32)/1.8 – 273 )}
T (˚F): R
T
0:[32˚F] 15k'
10:[50˚F] 9.6k' 40:[104˚F]
20:[68˚F] 6.3k'
25:[77˚F] 5.2k'
Medium temperature thermistor
• Thermistor <Heatsink> (TH8)
Thermistor R50 = 17k' ± 2%
B constant = 4170 ± 3%
1
t (:): Rt =17exp{4170( 273+t – 323 )}
=17exp{4170( 273+(T– 32)/1.8 – 323 )}
T (˚F): R
T
0:[32˚F] 180k'
25:[77˚F] 50k'
50:[122˚F] 17k'
70:[158˚F] 8k'
90:[194˚F] 4k'
High temperature thermistor
• Thermistor <Discharge> (TH4)
Thermistor R120 = 7.465k' ± 2%
B constant = 4057 ± 2%
t (:): Rt =7.465exp{4057( 273+t – 393 )}
=7.465exp{4057( 273+(T– 32)/1.8 – 393 )}
T (˚F): R
T
20:[68˚F] 250k'
30:[86˚F] 160k'
40:[104˚F] 104k'
50:[122˚F] 70k'
60:[140˚F] 48k'
1
1 1
30:[86˚F] 4.3k'
3.0k'
1
1 1
1 1
1 1
70:[158˚F] 34k'
80:[176˚F] 24k'
90:[194˚F] 17.5k'
100:[212˚F] 13.0k'
110:[230˚F] 9.8k'
50
40
30
20
10
0
-20 -10 0 10 20 30 40 50
-4 -14 32 50 68 86 104122
200
150
100
50
0
25
77
500
400
300
200
100
0
25
77
57
:
°F
Temperature
:
50 75 100 110 125
°F
122 167 212 230 257
Temperature
:
50 75 100 120
°F
122 167 212 248
Temperature