Heating Mode - Carrier 42QFD048D8S Service Manual

3.4.4 Condenser Temperature Protection
When condenser temperature is more than setting value,
the compressor ceases operation..
3.4.5 Evaporator Temperature Protection
When evaporator temperature drops below a configured
value, the compressor and outdoor fan cease operation.
3.5 Heating Mode(Heat pump units)
3.5.1 Compressor Control
1) Reach the configured temperature
• If the following conditions are satisfied, the
compressor ceases operation.
• While calculated frequency(fb) is less than
minimum limit frequency(FminH).
• When protective time is more than or equal to ten
minutes.
• When T1 is higher than or equal to Tsc+
HDIFTEMP2.
Note: HDIFTEMP2 is EEPROM setting parameter. It is 2°C
usually.
• If one of the following conditions is satisfied, not
judge protective time.
• Compressor running frequency is more than test
frequency.
• When compressor running frequency is equal to
test frequency, T4 is higher than 15°C or T4 sensor
fault.
• Change setting temperature.
• Turbo function on/off.
2) When the current is higher than the predefined safe
value, surge protection is activated, causing the
compressor to cease operation.
3.5.2 Indoor Fan Control:
• When the compressor is on, the indoor fan speed can
be set to high, (medium) ,low, or auto. And the anti-
cold wind function has the priority.
• Anti-cold air function
• The indoor fan is controlled by the indoor unit coil
temperature T2.
• Auto fan action in heating mode:
3.5.3
Case 1:
• The outdoor unit will be run at different fan speed
according to T4 and compressor frequency.
• For different outdoor units, the fan speeds are
different.
Case 2:
• The outdoor unit will be run at different fan speed
according to T4.
• For different outdoor units, the fan speeds are
different.
3.5.4
• The unit enters defrosting mode according to the
temperature value of T3 and T4 as well as the
compressor running time.
• In defrosting mode, the compressor continues to run,
the indoor and outdoor motor will cease operation,
the defrost light of the indoor unit will turn on, and
the "
• If any one of the following conditions is satisfied,
defrosting ends and the machine switches to normal

heating mode:

• T3 rises above TCDE1.
 Product Features
Outdoor Fan Control:
Defrosting mode
" symbol is displayed.
5 