Carrier 40QNH - Unit Operation Issues; Cooling and Heating Performance Issues

Table 10 — 40QN Thermistor Properties*
TEMP
(F)
MINIMUM
OHMS
NOMINAL
OHMS
MAXIMUM
OHMS
MINIMUM
THERMISTOR
VOLTS — DC
NOMINAL
THERMISTOR
VOLTS — DC
MAXIMUM
THERMISTOR
VOLTS — DC
−40 303,300 342,700 386,200 4.80 4.82 4.84
−30 211,500 237,276 265,444 4.72 4.75 4.77
−20 149,721 166,689 185,146 4.61 4.65 4.68
−10 107,379 118,776 130,973 4.48 4.52 4.55
0 77,281 85,677 93,867 4.30 4.35 4.40
10 56,567 62,617 68,205 4.09 4.16 4.21
20 42,661 46,302 50,129 3.86 3.92 3.98
30 32,043 34,580 37,220 3.59 3.66 3.72
32 30,300 32,550 35,120 3.53 3.60 3.66
40 24,061 26,118 27,960 3.28 3.36 3.43
50 18,650 19,900 21,180 2.99 3.05 3.11
60 14,402 15,312 16,219 2.67 2.73 2.79
70 11,247 11,883 12,518 2.36 2.42 2.47
80 8,820 9,299 9,779 2.06 2.11 2.16
90 6,846 7,339 7,754 1.76 1.83 1.88
100 5,487 5,829 6,187 1.52 1.57 1.63
110 4,367 4,667 4,976 1.29 1.34 1.40
120 3,502 3,760 4,026 1.09 1.14 1.19
130 2,830 3,051 3,281 0.92 0.97 1.02
140 2,300 2,489 2,687 0.77 0.82 0.87
150 1,880 2,045 2,216 0.65 0.69 0.74
160 1,547 1,688 1,836 0.55 0.59 0.63
170 1,280 1,402 1,531 0.46 0.50 0.53
180 1,065 1,170 1,282 0.39 0.42 0.45
190 890 982 1,078 0.33 0.36 0.39
200 748 828 913 0.28 0.31 0.33
210 631 701 766 0.24 0.26 0.28
212 611 678 751 0.23 0.25 0.28
*Circuit volts = 5 vdc.
Table 11 — Troubleshooting
PROBLEM POTENTIAL SOURCE ACTION
Unit does not operate
Circuit breaker has tripped or fuse is blown Reset the circuit breaker or replace the fuse.
Power failure
Restart fan coil unit operation when power is
restored.
Voltage is too low Confirm the available voltage.
Insufficient Cooling
Air filter is blocked with dust Clean the air filter.
Temperature is not set properly Check and reset if necessary.
Window(s) and/or door(s) are open Close window(s) and door(s).
Outdoor unit is obstructed Remove the obstruction.
Fan speed is too low Change the fan speed
Operation mode is set to fan or auto. mode
Change to cooling operation or reset temperature
(using remote controller).
Insufficient Heating*
Air filter is blocked with dust Clean the air filter.
Temperature is not set properly Check and reset if necessary.
Window(s) and/or door(s) are open Close window(s) and door(s).
Outdoor unit is obstructed Remove the obstruction.
Unit stops during operation
Off timer is operating Turn off the off timer function.
Room temperature has reached the programmed
set point
Normal unit operation.
*Heat pump systems only.
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