Hvac CVH8, Service Manual

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CVH8, HVH8, TVH8, VA9, HVA9, TVA9: APPLICATION GUIDELINE & SERVICE MANUAL
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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A14022
Fig. 30 – 50K Thermistor Resistance Vs Temperature
If the outdoor air or coil thermistor should fail, the control will flash the
appropriate fault code (see Table 10 ).
The outdoor air thermistor, coil thermistor and suction thermistor should
be factory mounted in the final locations. Check to ensure thermistors
are mounted properly (See Fig. 2 through Fig. 6 ).
Thermistor Sensor Comparison
The control continuously monitors and compares the outdoor air
temperature sensor and outdoor coil temperature sensor to ensure proper
operating conditions. The comparison is:
• In cooling if the outdoor air sensor indicates ³10°F (³5.6°C) warmer
than the coil sensor (or) the outdoor air sensor indicates ³25°F (³15°C)
cooler than the coil sensor, the sensors are out of range.
• In heating if the outdoor air sensor indicates ³35°F (³19.4°C) warmer
than the coil sensor (or) the outdoor air sensor indicates ³10°F (³5.6°C)
cooler than the coil sensor, the sensors are out of range.
If the sensors are out of range, the control will flash the appropriate fault
code as shown in Table 10 .
The thermistor comparisons are not performed during low ambient
cooling or defrost operation.
Failed Thermistor Default Operation
Factory defaults have been provided in the event of failure of outdoor air
thermistor (OAT) and/or outdoor coil thermistor (OCT).
If the OAT sensor should fail, defrost will be initiated based on coil
temperature and time.
If the OCT sensor should fail, defrost will occur at each time interval
during heating operation, but will terminate after 2 minutes.
If there is a thermistor out-of-range error, defrost will occur at each time
interval during heating operation, but will terminate after 2 minutes.
Count the number of short and long flashes to determine the appropriate
flash code. Fig. 31 and Table 10 gives possible causes and actions
related to each error.
Maximum Power Mode - Inverter over Temperature
The outdoor unit is equipped with inverter temperature sensing. If the
inverter senses a temperature above the high threshold limit, it will
respond as follows:
1. Display the local fault code only on the AOC Status LED.
2. The system will continue to run, but attempt to mitigate by speed
reduction.
3. When the system demand is satisfied, the unit will shut down.
4. If the fault is still active on the AOC Status LED, the ODF will
continue to run at 500 rpm until the inverter temperature falls below
the threshold.
5. The compressor will not restart if the fault is still active.
FAULT CODES / DESCRIPTIONS
A170002
Fig. 31 – Fault Code Label