How To Check The Components; Thermistor Feature Chart; Low Temperature Thermistors; Medium Temperature Thermistor - Mitsubishi Electric PUZ-A18NHA4 Service Manual

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%
=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"
20:[68˚F] 6.3k"
25:[77˚F] 5.2k"

Medium temperature thermistor

• Thermistor <Heatsink> (TH8)
Thermistor R50 = 17k" ± 2%
B constant = 4170 ± 3%
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) <for A42>
• Thermistor <Shell> (TH32) <for A12/18/24/30/36>
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 1
30:[86˚F] 4.3k"
40:[104˚F] 3.0k"
1 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 °F
200
150
100
50
0
500
400
300
200
100
0
57
Temperature
25 50 75 100 110 125
77 122 167 212 230 257 °F
Temperature
50 75 100
25
122 167 212
77
Temperature
120
248 °F