Protection Circuit Fault Isolation - Friedrich Floating Air Pro Multi-Zone FPHMR42A3A Service Manual

TROUBLESHOOTING

Protection Circuit Fault Isolation

Protection diagnosis of the complete machine (all types of protection during operation, i.e. under-voltage, over-voltage
and overcurrent protection)
Note:List all types of protection that may occur to the complete machine and describe the conditions and signs of the start,
course and end of such protection.
Voltage protection
Protection against AC input over-voltage/under-voltage
1.Conditions for protection against AC input over‑voltage/under‑voltage:
If the input AC voltage is greater than "protective over‑voltage value" or less than "protective under‑voltage value" for five
seconds, over‑voltage/under‑voltage protection starts. (E6)
2.Protection actions against AC input over‑voltage/under‑voltage
The system stops operation.
3. Conditions for ending AC input over‑voltage/under‑voltage:
If the input AC voltage is lower than "the protective over‑voltage value" ‑10V, or higher than "the protective under‑voltage
value" +10V, the over‑voltage/under‑voltage protection will be released.
Current protection:
1.Protection against over‑current
Conditions for over‑current protection: if the current is equal to or greater than "current value for starting the refrigeration
current protection (E2 value)" for six seconds, over‑current protection starts.
Protection actions against over‑current: indoor display screen and outdoor indicator give indications, the compressor and
outdoor fan stop, but indoor fan runs normally.
Condition for ending over‑current protection: when the current drops below "current value for releasing the refrigeration
current protection (E2 value)", over‑current protection will be released.
2.Frequency decreasing for over‑current
Conditions for over‑current frequency decreasing: if the current is equal to or greater than "current value for starting the
refrigeration current protective frequency decreasing (E2 value)", over‑current frequency decreasing starts.
Over‑current frequency decreasing actions: the compressor will decrease frequency at rate of (E2 value)Hz/S. The indoor and
outdoor fans run.
Conditions for ending over‑current frequency decreasing: when the current drops below "current value for starting the
refrigeration current protective prohibition of frequency rising (E2 value)", over‑current under‑clocking will be released.
*Is the limit auto-reset*
3.Prohibition of frequency increasing of compressor exhausting
Conditions for prohibition of frequency rising of compressor discharge
Condition 1: in the case of frequency decreasing of compressor discharge, the discharge temperature of the compressor
drops below 39.2F
Condition 2: in normal operation, the discharge temperature of compressor reaches 41F.
Either of the above two conditions is met, prohibition of frequency rising of compressor discharge begins.
Actions relates to prohibition of frequency rising of compressor discharge: the frequency of compressor maintains at the
current level, which may decrease as the case requires while cannot rise. The indoor and outdoor fans run.
Condition for ending prohibition of frequency rising of compressor discharge: if the temperature of compressor discharge
rises above 42.8F, prohibition of frequency rising of compressor discharge will be released.
4. Prohibition of frequency for anti-overload of outdoor coiled pipe (cooling condenser temperature high) – To prevent
compressor overload from tripping.
Condition for anti‑overload prohibition of frequency of outdoor coil pipe: in the case of anti‑overload frequency decreasing
of outdoor coiled pipe, anti‑overload prohibition of frequency of the unit begins when the temperature of outdoor coiled pipe
drops below "the anti‑overload frequency decreasing temperature of outdoor coiled pipe".
Actions relates to anti‑overload prohibition of frequency of outdoor coiled pipe: the frequency of compressor maintains at the
current level, which may decrease as the case requires while cannot rise. The indoor and outdoor fans run.
Condition for ending anti‑overload prohibition of frequency of outdoor coiled pipe: if the temperature of outdoor coiled pipe
drops below "temperature to release the anti‑overload state of outdoor coiled pipe", anti‑overload prohibition of frequency of
outdoor coiled pipe will be released.
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