Hoshizaki rf28a Manual Suplementar

3

Please review this manual. It should be read carefully before the unit is serviced or 
maintenance operations are performed. Only qualified service technicians should service 
and maintain the unit. This manual should be made available to the technician prior to 
service or maintenance. 

1. RR28A, RF28A ........................................................................................................ 6
2. RR55A, RF55A ........................................................................................................ 7

A. Sequence of Operation ................................................................................................. 8
B. Time-Temperature Control Chart .................................................................................. 9
C. Control Board .............................................................................................................. 10

1. Adjusting the Setpoint Temperature ....................................................................... 12
2. Settings and Diagnostics Menu ............................................................................. 13

a) Defrost Interval (F0) .......................................................................................... 14
b) Setpoint Temperature Differential (F2) .............................................................. 14
c) High Temperature Alarm Delay Time (F3) ......................................................... 15
d) Low Temperature Alarm Delay Time (F4) .......................................................... 15
e) Temperature Display – °F or °C (F5) ................................................................. 16
f) Alarm History (F6) .............................................................................................. 16
g) Compressor Run Time (F7) ............................................................................... 17
h) Not in Use (F8) .................................................................................................. 17
i) High Temperature Shutoff Temperature Setting (FA) .......................................... 17
j) Not in Use (Fb) ................................................................................................... 17

1. Alarm Display Priority ............................................................................................ 20
2. Alarm Details and Countermeasures .................................................................... 21

a) High Temperature Alarm (E1) ............................................................................ 21
b) Low Temperature Alarm (E2) ............................................................................. 22
c) Defrost Alarm (E3) ............................................................................................. 23
d) High Pressure Alarm (E4) ................................................................................. 23
e) Clogged Filter Alarm (E7) .................................................................................. 24
f) Defrost Thermistor Malfunction Alarm (E8) ........................................................ 25
g) Clogged Filter Thermistor Malfunction Alarm (E9) ............................................ 26
h) Control Board Error Alarms (EA and ED) .......................................................... 27

B. Diagnostic Chart ......................................................................................................... 28
C. Thermistor Check ........................................................................................................ 32