Checking Transformer And Control Circuit - Goodman ACS series Service Instructions Manual

SERVICING
The heating anticipator setting for furnaces covered in this
manual is 0.70 Amps.
If the anticipator current draw is unknown, then a current
amp draw should be measured to determine the anticipator
setting. Use an amprobe as shown in the following drawing.
Checking Heating Anticipator Current (Amp) Draw
Cooling Anticipator
The cooling anticipator is a small heater (resistor) in the
thermostat. During the "OFF" cycle it heats the bimetal ele-
ment helping the thermostat call for the next cooling cycle.
This prevents the room temperature from rising too high be-
fore the system is restarted. A properly sized anticipator
should maintain room temperature within 1 1/2 to 2 degrees.
The anticipator is fixed in the subbase and is not to be re-
placed. If the anticipator should fail for any reason, the sub-
base must be changed.
S-4 CHECKING TRANSFORMER AND CONTROL
CIRCUIT
A step-down transformer 120 volt primary to 24 volt second-
ary, 40 VA (Heating and Cooling Models) supplies ample
capacity of power for either operation.
HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFORE SERVICING OR
CHANGING ANY ELECTRICAL WIRING.
F
SOURCES MAY BE PRESENT. AILURE TO DO SO MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
1. Remove blower compartment door to gain access to the
thermostat low voltage wires located at the furnace inte-
grated control module.
2. Remove the thermostat low voltage wires at the furnace
integrated control module terminals.
With Power On (and Door Interlock Switch closed):
100
10 TURNS OF
THERMOSTAT WIRE
(From "W" on thermostat)
STATIONARY JAW
OF AMPROBE
READS 4 AMPS
CURRENT DRAW
WOULD BE .4 AMPS
WARNING
M
ULTIPLE POWER
WARNING
L
INE VOLTAGE NOW PRESENT
3. Use a voltmeter, check voltage across terminals R and
C. Must read 24 VAC.
4. No voltage indicates faulty transformer, open fuse, bad
wiring, bad splice, or open door interlock switch.
5. Check transformer primary voltage at incoming line volt-
age connections, fuse, splices, and blower door inter-
lock switch.
6. If line voltage is available to the primary side of trans-
former and not at secondary side, the transformer is
inoperative. Replace.
7. After completing check and/or replacement of trans-
former and check and/or repair of control circuit, rein-
stall blower compartment door.
8. Turn on electrical power and verify proper unit operation.
S-10B Capacitance Check
VOLT / OHM
METER
AMMETER
Testing Capacitance
With power On (and Door Interlock Switch closed):
WARNING
L
INE VOLTAGE NOW PRESENT
Using a hookup as shown above, take the current and volt-
age readings and use them in the formula:
Capacitance (MFD)= 2650 x Current/Voltage
4. After completing check and/or replacement of capaci-
tor, reinstall blower compartment door.
5. Turn on electrical power and verify proper unit operation.
15 AMP FUSE