Service Manual

Table Of Contents

f) Glass Door Cabinet Light Diagnosis: LED(s) are activated from control module

light switch. Glass door models feature lights that are controlled by the Standby/Light

control button located on the control module. Press the standby/light button quickly

to turn the light on or off. If LED(s) fail to turn on, check for 115VAC from CM 6 (LED)

(Y) to a neutral (W). If 115VAC is not present at CM 6 (LED) (Y)to a neutral (W),

replace CM. If 115VAC is present at CM 6 (LED) (Y) to a neutral (W) and LED(s) are

not on, check for 24VDC at DCD black (BK) wire to DCD red (R) wire. If 24VDC is

not present, check continuity of DCD driver. If open, replace DCD driver. If 24VDC is

present and LED(s) are not on, check wiring harness and wiring connections from

DCD to LED(s). Ifconnections are good and LED(s) are not on, replace LED(s).

g) CM Diagnosis: Cabinet temperature appears on display. If not, check for 115VACat

CM 2 (L) (BK) to CM 3 (N) (W). If 115VAC is not present, check power cord

connections and breaker/fuse. Conrm wiring connections are secure for both

CM 2 (L) (BK) (power supply) and CM 3 (N) (W). If 115VAC is present and display is

off, replace CM.

h) Comp and ConFM Diagnosis: Conrm Comp and ConFM energize. Ifnot, check

for 115VAC at CM 1 (C) (V) to a neutral(W). If 115VAC is not present, check CTh

status. See "II.D. Thermistor Check." IfCTh ohm reading is in proper range, replace

CM. If not in range, replace thermistor. If115VAC is present at CM 1 (C) (V) to a

neutral (W), check for 115VAC at both HPS (V) wires to a neutral(W). If 115VAC

is present on one and not the other, check HPS continuity. If open, allow time for

HPS to reset. If HPS does not reset, see "i) HPS Activation" below. If HPS is closed

and 115VAC present on both HPS (V) wires to a neutral (W), check for 115VAC at

condensing unit receptacle and condensing unit power supply cord (BK) to a neutral

(W). If 115VAC is not present at condensing unit receptacle or power supply cord

(BK), correct loose wiring or replace receptacle or power supply cord. If 115VAC is

present at condensing unit power supply cord (BK) and ConFM is energized but

Comp is not, check for 115VAC at both Comp external protector wires to a neutral

(W). If 115VAC is present on one and not the other, external protector is open.

Give external protector time to cool and reset. If Comp external protector does not

reset, replace Comp external protector. If 115VAC is present on both Comp external

protector wires, check Comp start capacitor, start relay, and Comp motor windings,

replace as needed. If Comp does not start, replace condensing unit. If ConFM is not

energized, check ConFM fan blades for binding and motor winding continuity.

If Comp and ConFM are energized and the cabinet does not cool down, check for a

restriction in the refrigeration circuit, correct TXV operation, and correct refrigerant

charge. See nameplate for correct charge amount.

i) HPS Activation: Conrm ConFM is energized and fan blade turns freely.

Conrmcondenser coil is not clogged or restricted. Conrm there are no restrictions

in the refrigeration circuit (TXV and drier). Let refrigeration circuit pressures equalize.

IfHPS does not reset and pressures are equalized, replace HPS. Ifpressures are

not equalized, reclaim refrigerant and diagnose refrigeration circuit restriction.