Input Current Control; Freeze-Up Protection Control; Management Within The Zones; Conditions For Start Controlling - Friedrich MWM09Y1J Service Manual

Management within the Zones

Stop zone
Drooping zone
Keep zone
Return / Reset zone

Input Current Control

Outline
Detect an input current by the CT during the compressor is running, and set the frequency upper limit from such input current.
In case of heat pump model, this control is the upper limit control function of the frequency which takes priority of the lower limit of four
way valve activating compensation.
Detail
The frequency control will be made within the following zones.
When a "stop current" continues for 2.5 seconds after rushing on the stop zone, the compressor operation stops.
If a "drooping current" is continues for 1.0 second after rushing on the drooping zone, the frequency will be 2 Hz drooping.
Repeating the above drooping continues until the current rushes on the drooping zone without change.
In the keep zone, the frequency limit will remain.
In the return / reset zone, the frequency limit will be cancelled.
Limitation of current drooping and stop value according to the outdoor air temperature
1. In case the operation mode is cooling
* The current droops when outdoor air temperature becomes higher than a certain level (model by model).
2. In case the operation mode is heating
* The current droops when outdoor air temperature becomes higher than a certain level (model by model).

Freeze-up Protection Control

Outline
During cooling operation, the signals being sent from the indoor unit allow the operating frequency limitation and then prevent freezing
of the indoor heat exchanger. (The signal from the indoor unit must be divided into the zones as the followings.)
Detail

1.Conditions for Start Controlling

Judge the controlling start with the indoor heat exchanger temperature after 2 sec from operation start.
2.Control in Each Zone
Z o n e
When the temperature reaches the stop zone, stop the compressor and
correct abnormality.
Start the timer, and the frequency will be drooping.
Keep the upper limit of frequency.
Cancel the upper limit of frequency.
2 Hz drooping
1.0second after
rushing in the
drooping zone
1
2
3
Heat exchanger
thermistor temperature
A
B
C
D
E
C o t n o r c l o n e t n s t
After 2.5 seconds
Compressor stops
Stop zone
Drooping zone
Keep zone
Reset zone
Return/Reset zone
Up zone
Keep zone
Drooping zone
Stop zone
Technical Information