DEFROST CONTROL CIRCUITS
The different defrost systems shown on the wiring
diagrams all work from the same basic circuit. The
variations come from tailoring the systems to the
customers’ needs by selection of components used
to accomplish defrost.
The basic circuit is controlled by a defrost clock
which closes the circuit, energizing relay coil R1.
R1 controls
one
contact 1R1 (normally closed)
and
two
contacts 2R1 (normally open). NC 1R1
controls refrigeration components. NO 2R1’s con-
trol defrost components. As the system require-
ments vary so will the components controlled by
the contacts.
Once begun, defrost continues until the defrost
termination thermostat or defrost clock opens the
defrost circuit de-energizing relay coil R1.
ELECTRICAL
September 1, 1997
4 - 24
HUSSM ANN CORPORATION • BRIDGETON, M O 63044-2483 • Printed in USA
X1
T1
1R1
FUSE
5AMP
2R1
P1,1
P1,2
Mech. Def
Clock
Fibertronic
Defrost
Clock
R__
F__
P3,1
P3,2
Q2
J4
J5
ON/OFF
R1
TEMP
TERM
i
4 21
f
C
l Ci
i
Figure 4-18 — Defrost Control Circuit
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