¥ A reversing valve defrosting format is used, and the defrosting cycle consists of [balancing period of 90 seconds when defrosting starts -> reverse cycle

period for 12 minutes maximum -> balancing period of 90 seconds when defrosting stops]. Since this system uses the outdoor heat-exchanger concurrently

in two cycles, defrosting is executed for both cycles during 2-cycle heating operation.

(1) Defrosting start conditions

¥ Defrosting is performed when all the following conditions are satisfied (however, this does not apply when a defrosting request from another cycle is

received.):

For normal operation

①

Heat-exchanger low temperature (heat-exchanger temperature

②

When defrosting inhibit time is up (instructed by EEPROM [FLGSET (3.2.1)] and set when normal operation is started)

③

(2) Defrosting stop conditions

¥ Defrosting is released when either of the following conditions is established (however, defrosting will continue when a defrosting request from another

cycle is received.):

Heat-exchanger temperature is recovered (heat-exchanger temperature

①

When maximum defrosting time (12 minutes) is up

②

Release during balancing at start: To be returned to normal when remaining balancing time is up.

※

Release during reverse cycle period: To be returned to normal when balancing time (90 seconds) is up at the end.

(3) Outputs during defrosting

[Defrosting request between outdoor microcomputers] To be transferred only when heat-exchanger low temperature is detected and defrosting is being

executed.

[Indoor defrosting request] To be transferred to all units which are in heating operation.

[Compressor] To increase the speed at the rate of DFSTEP rpm/TDFSPT second and reach the maximum defrosting speed [DEFMAX].

[Expansion valves] Units with compressor off: To be fully closed when defrosting starts and the balancing time (30 seconds) is up.

Units with compressor on: To be opened by [DFSPPS] pulses, synchronized with a step-up of rotation speed, and fully opened

[DFPSMX] when the speed reaches [DEFMAX].

If there is no compressor on machine in one cycle, the above control can be performed by turning the operation bit on and off.

※

(4) Special remarks

¥ During one-cycle heating operation, defrosting should be executed with one cycle only. Other cycles should remain in the stop mode.

¥ During 2-cycle heating operation, defrosting is released and finished for both cycles. Therefore, each period may exceed the specitied time.

¥ If unit fails and stops while defrosting is being executed by a defrosting request issued from another cycle, defrosting will be executed from start (for

balancing 90 seconds) after balancing 3 minutes are up and failure is released.