Nor-Lake Ice Cream Dipping-Display Merchandisers - Manual (Page 8)

8
OPERATION CONDITIONS AND PRESSURES
With room ambient temperature of +80
o
F and cold cabinet (unit cycling on control):
HF160 & HF230 with R-404a
Suction pressure – 6 to 8 psig.
Head pressure – 240 to 260 psig.
If room ambient is low, 60
o
F or lower, then the suction pressure could be as low as 4 psig. Temporary block the
condenser coil to raise head pressure to 240 psig in order to verify proper charge and a suction pressure of 6psig
to 8 psig. Remove blockage after pressure check.
HF040 & HF100 with R-134a
Suctions pressure –5 to –8 inches vacuum
Head pressure 105 to 110 psig
If room abient is below 70
o
F temporarily block the condenser coil to raise the head pressure to 105 psig and
recheck suction pressure. Add R-134a if suction pressure is lower than –8 inches of vacuum.
SERVICE INSTRUCTIONS (Trouble Shooting Guide)
1.
High head pressure and high back
pressure:
A.
Condenser coil clogged or
restricted.
B. Condenser fan motor defective.
C. Air in the system.
D. Refrigeration overcharge.
2. Low back pressure and low head
pressure:
A.
Capillary tube restriction.
B. Refrigerant undercharged.
C. Leak in system.
D. Moisture in system.
3. Pressures normal – cabinet warm:
A. Refrigerant
undercharged.
B. Thermostat set too warm.
4. Compressor starts and runs – but cycles
on overload:
A. Low
voltage.
B. Overload protector defective.
C. High head pressure (see#1).
5. Compressor will not start – hums, but
cycles on overload:
A. Low
voltage.
B. Relay defective.
C. Overload defective.
D. High head pressure (see #1).
6. Cabinet sweating:
A. High ambient humidity.
7.
Special service situations