GMEC96 Service Manual

60
SERVICING
R7 8 3
R7 8 2
R781
R7 8 4
E13
T1
E190
T2
E8
T4
E9
T3
R94
R9 5
R96
R97
K11
K2 K1
K3
R V
2
G L 2
GL1
E39
W32
W40
R58
W11
R75
R118
W36
W37
W53
Q72
M2
Q71
Q70
Q3
Q6
Q2
Q7
Q5
Q60
Q4
Q14
Q10
Q11
Q13
Q9
W46
W12
W14
W49
W52
W24
W51
W33
W20
R78
W31
R201
R588
R59
R780
R524
R3
R584
R586
R4
R15
R76
R71
W35
W30
W13
W1
CR13
R566
R87
R31
R
9
R580
R568
R578
R70
R53
W15
W3
W7
W18
W34
W19
W29
W16
W2
W10
W44
R553
W22
R91
R82
W4
S2
F1
DS1
S1
R
R81
R202
R119
R557
R570
R573
R564
R581
C11
R63
R38
R85
E3 5
E36
R2
R33
R74
R73
R21
R44
R54
R65
R130
R27
R29
R41
R200
R77
R563
R562
R10
R115
R40
R50
R39
R49
R204
R35
RV4
RV3
C13
C60
C14
C15
R93
R89
R17
R16
R12
R11
R61
R13
R18
R79
E2 9
CIRC-H
E28
HUM
E16
XF MR
E15
L1
E10
EAC-H
E2 1 E2 0 E18 E17 E19
K8
K9
K5
K6
K4
E4 0
E12
U3
SW3
2
3
4
E2
E6
C
E5
G
E4
R
E3
W1
E3 1
Y
E32
TWIN
OFF ON
E26 E27
1
2
3
4
3
2
1
ST5
ST1
ST2
ST6
ST4
ST3
ERROR
L AST
ST AT US
+
(1VDC=1uA)
CURRENT
FLAME
CAUTI ON - 120V
NEUT RAL S
R60
K10
Yl 0
Y
W1
W2R
GCTWIN
E2 2
OFF
ON
W39
E14
R88
R92
59- 5043 REV . D
IGN SYSTEM 24VAC 60Hz. 0.5A MAX
PCBBF133 Control Board
4. After the ignitor warmup time, begin checking for 24
volts to the gas valve. Voltage will be present for four
seconds only if proof of flame has been established.
5. If proof of flame was established voltage will be provided
to the air circulation blower following the heat on delay
period.
S-314 CHECKING FLAME SENSOR
A flame sensing device is used in conjunction with the igni-
tion control module to prove combustion. If proof of flame is
not present the control will de-energize the gas valve and
"retry" for ignition or lockout.
WARNING
HIGH VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY
BE PRESENT.
F
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
Flame current can be measured in two ways:
1. Putting a D.C. microamp meter in series with the
flame rod
2. Putting a D.C. volt meter across the two solder pads
in the flame current section of the control board.
1 D.C. volt = 1 microamp.
Flame Current
Solder Pads
L
INE VOLTAGE NOW PRESENT
WARNING
3. As soon as flame is established a micro-amp reading
should be evident once proof of flame (micro-amp read-
ing) is established, the hot surface ignitor will be de-
energized.
4. The Integrated Ignition controls will have 1 to 4 micro-
amps. If the micro-amp reading is less than the mini-
mum specified, check for high resistance wiring con-
nections, sensor to burner gap, dirty flame sensor, or
poor grounding.
5. If absolutely no reading, check for continuity on all com-
ponents and if good - replace ignition control module.
NOTE: Contaminated fuel or combustion air can create a
nearly invisible coating on the flame sensor. This coating
works as an insulator causing a loss in the flame sense
signal. If this situation occurs the flame sensor must be
cleaned with steel wool.