SERVICING
21
S-4 CHECKING TRANSFORMER
AND CONTROL CIRCUIT
WARNING
HIGH VOLTAGE!
Disconnect ALL power before servicing or installing.
Multiple power sources may be present. Failure to do
so may cause property damage, personal injury
or death.
A step-down transformer (208/240 volt primary to 24 volt sec-
ondary) is provided with each indoor unit. This allows ample
capacity for use with resistance heaters. The outdoor sec-
tions do not contain a transformer.
WARNING
Disconnect ALL power before servicing.
1. Remove control panel cover, or etc., to gain access to
transformer.
With power ON:
WARNING
Line Voltage now present.
2. Using a voltmeter, check voltage across secondary volt-
age side of transformer (R to C).
3. No voltage indicates faulty transformer, bad wiring, or bad
splices.
4. Check transformer primary voltage at incoming line volt-
age connections and/or splices.
5 If line voltage available at primary voltage side of trans-
former and wiring and splices good, transformer is inop-
erative. Replace.
S-5 CHECKING CYCLE PROTECTOR
Some models feature a solid state, delay-on make after break
time delay relay installed in the low voltage circuit. This
control is used to prevent short cycling of the compressor
under certain operating conditions.
The component is normally closed (R
1
to Y
1
). A power
interruption will break circuit (R
1
to Y
1
) for approximately three
minutes before resetting.
1. Remove wire from Y
1
terminal.
2. Wait for approximately four (4) minutes if machine was
running.
With power ON:
WARNING
Line Voltage now present.
1. Apply 24 VAC to terminals R
1
and R
2
.
2. Should read 24 VAC at terminals Y
1
and Y
2
.
3. Remove 24 VAC at terminals R
1
and R
2
.
4. Should read 0 VAC at Y
1
and Y
2
.
5. Reapply 24 VAC to R1 and R2 - within approximately
three (3) to four (4) minutes should read 24 VAC at Y
1
and
Y
2
.
If not as above - replace relay.
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
delays are also used in electric heaters to sequence in
multiple electric heaters.
WARNING
Disconnect ALL power before servicing.
1. Tag and disconnect all wires from male spade connec-
tions of relay.
2. Using an ohmmeter, measure the resistance across
terminals 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
continuity across other terminals - should test continu-
ous. If not as above - replace.
NOTE: The time delay for the contacts to make will be
approximately 20 to 50 seconds and to open after the coil is
de-energized is approximately 40 to 90 seconds.
OHMMETER
TESTING COIL CIRCUIT
(20 pages)
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