Testing & Troubleshooting - Garland moisture+ MP-GD-10-S Service Manual

TESTING & TROUBLESHOOTING
MP-GS-10/20 Troubleshooting Guide
Use this chart with the appropriate wiring diagram, also found in this manual
PROBLEM
Fan will not Run
PROBLEM
Key Pad Buttons Not
Responding
PROBE ERROR in display
HI TEMP In display
HELP In display
Unit will not shut off
No HIGH speed But LOW
speed works
No LOW speed But HIGH
speed works
Display is BLANK NO
POWER
Unit will not heat
Motor stops, then after a
period of time comes back
on
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Mechanical Control
POSSIBLE CAUSE
No Power to Oven
No Power to Oven
Micro switch not OPENING
POSSIBLE CAUSE
Defective key pad
Loose ribbon connection at key pad
Faulty Probe
Loose probe connection
Oven at too high a temp for product
Faulty Probe
Motor centrifugal switch stuck
Gas valve (s), or Ignition System
Unit above 150°F
Bad key pad
Bad K2 relay on board
Bad motor
Bad key pad
Bad K2 relay on board
Bad motor
Bad transformer
Bad harness connection
No power out of K4 relay
No power out of Ignition Module MV
Gas valve shutoff switch open, PV, MV,
or both valves stuck closed
Motor centrifugal not closing
Thermal Trip on motor
Turn power on
Check Light circuit – IF OK, Select "Cook" and Check
Timer circuit . IF OK, Check Door Micro Switches
Check connections & switch functions .
(Caution: the switch components on this control
system pass 115 v . a .c . through switch contacts .)
Fast Control
Use key pad diagnostics / pin outs test points
Check connection
Replace probe
Check connections
Allow oven to cool
Replace probe
Check centrifugal switch
Check heat generation system – ( Refer to Service
procedures (Heat generation system) - .page
Put unit into cool down, open door slightly
Use diagnostic KEY PAD TEST
Check for voltage out of K2 relay
Check motor
Use diagnostic KEY PAD TEST
Check for voltage out of K3
Check motor
Check for 24VAC out of TR1 transformer
Check connections
Check for power out of K4 relay
Complete a flame current check to osolate
Check for MV power at gas shutoff switch, and that
PV and MV opens on call for heat
Check motor centrifugal switch
Inspect rear clearance
Motor air intake is clear of lint/debris
Replace motor
CORRECTIVE ACTION
CORRECTIVE ACTION
Part # MPSM07 (03/24/08)