Carrier 42QHF009DS Service Manual page 46

HEAT_F10
HEAT_F9
HEAT_F8
HEAT_F7
HEAT_F6
HEAT_F5
If the current frequency is lower than HEAT_F4, the frequency will not be limited.
After 10s of the compressor start, if the current>IHEAT, the AC will display the failure for 30 seconds and stop. The AC
will restart 3 minutes later.
11.6.5 Indoor / outdoor units communication protection
If the indoor units can not receive the feedback signal from the outdoor units for 2 minutes, the AC will stop
and display the failure.
11.6.6 High condenser coil temp. protection.
When T3>65℃ for 3 seconds, the compressor will stop while the indoor fan and outdoor fan will continue.
When T3<52℃, the protection will release and the compressor will restart after 3 minutes.
11.6.7 Outdoor unit anti-freezing protection
For other models: When T2B<0℃ for 250 seconds, the indoor unit capacity demand will be zero and
resume to normal when T2B>10℃.
For M2OD-16HFN1-Q， M2OD-18HFN1-Q， M50D-42HFN1-Q: When T2<4℃ for 250 seconds or T2<0℃, the
indoor unit capacity demand will be zero and resume to normal when T2>8℃ and the time of protection is
no less than 3 minutes.
11.6.8 Oil return
Running rules:
1. If the compressor frequency keeps lower than RET_OIL_FREQ1_ADD for RET_OIL_TIME1_ADD, the
AC will rise the frequency to RET_OIL_FREQ2_ADD for RET_OIL_TIME2_ADD and then resume to
former frequency.
2. The EXV will keep 300p while the indoor units will keep the current running mode.
If the outdoor ambient is higher than TempT4HeatLimit_ADD during the oil return, the AC quit oil return.
11.6.9 Inverter module protection
The Inverter module has a protection function about current, voltage and temperature. If these protections
happen, the corresponding code will display on indoor unit and the unit will stop working.
11.6.10 Indoor fan delayed open function
When the unit starts up, the louver will be active immediately and the indoor fan will open 10s later.
If the unit runs in heating mode, the indoor fan will be also controlled by anti-cold wind function.
11.7 Operation Modes and Functions
11.7.1 Fan-only mode
(1) Outdoor fan and compressor stop.
(2) Indoor fan can be set to high/med/low/auto.
IHEATLMT6
IHEATLMT5
IHEATLMT4
IHEATLMT3
IHEATLMT2
IHEATLMT1
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