SERVICING
182 Rev. 3
S-6 CHECKING TIME DELAY RELAY
Time delay relays are used in some of the blower cabinets to
improve efficiency by delaying the blower off time. Time de-
lays are also used in electric heaters to sequence in multiple
electric heaters.
WARNING
Disconnect Electrical Power Supply:
1. Tag and disconnect all wires from male spade connec-
tions of relay.
2. Using an ohmmeter, measure the resistance across ter-
minals H1 and H2. Should read approximately 150 ohms.
3. Using an ohmmeter, check for continuity across termi-
nals 3 and 1, and 4 and 5.
4. Apply 24 volts to terminals H1 and H2. Check for conti-
nuity across other terminals - should test continuous. If
not as above - replace.
NOTE: The time delay for the contacts to make will be ap-
proximately 20 to 50 seconds and to open after the coil is de-
energized is approximately 40 to 90 seconds.
OHMMETER
TESTING COIL CIRCUIT
S-7 CHECKING CONTACTOR AND/OR RELAYS
The compressor contactor and other relay holding coils are
wired into the low or line voltage circuits. When the control
circuit is energized, the coil pulls in the normally open con-
tacts or opens the normally closed contacts. When the coil
is de-energized, springs return the contacts to their normal
position.
NOTE: Most single phase contactors break only one side of
the line (L1), leaving 115 volts to ground present at most
internal components.
WARNING
Disconnect Electrical Power Supply:
1. Remove the leads from the holding coil.
2. Using an ohmmeter, test across the coil terminals.
S-8 CHECKING CONTACTOR CONTACTS
WARNING
Disconnect Electrical Power Supply:
1. Disconnect the wire leads from the terminal (T) side of
the contactor.
2. With power ON, energize the contactor.
WARNING
LINE VOLTAGE NOW PRESENT
3. Using a voltmeter, test across terminals.
A. L2 - T1 - No voltage indicates CC1 contacts open.
If a no voltage reading is obtained - replace the contactor.
VOLT/OHM
METER
T1
T2
L1
L2
CC
Ohmmeter for testing holding coil
Voltmeter for testing contacts
TESTING COMPRESSOR CONTACTOR
S-9 CHECKING FAN RELAY CONTACTS
WARNING
Disconnect Electrical Power Supply:
1. Disconnect wires leads from terminals 2 and 4 of Fan
Relay Cooling and 2 and 4, 5 and 6 of Fan Relay Heating.
2. Using an ohmmeter, test between 2 and 4 - should read
open. Test between 5 and 6 - should read continuous.
3. With power ON, energize the relays.
WARNING
LINE VOLTAGE NOW PRESENT.
4. Using an ohmmeter, test between 2 and 4 - should read
continuous . Test between 5 and 6 - should read open.
5. If not as above, replace the relay.