Specifications

181 Rev. 3
SERVICING
Resistance Heaters
1. Set room thermostat to a higher setting than room tem-
perature so both stages call for heat.
2. With voltmeter, check for 24 volts at each heater relay.
3. No voltage, indicates the trouble is in the thermostat or
wiring.
4. Check the continuity of the thermostat and wiring. Re-
pair or replace as necessary.
NOTE: Consideration must be given to how the heaters are
wired (O.D.T. and etc.). Also safety devices must be checked
for continuity.
S-3B Cooling Anticipator
The cooling anticipator is a small heater (resistor) in the ther-
mostat. During the "off" cycle it heats the bimetal element
helping the thermostat call for the next cooling cycle. This
prevents the room temperature from rising too high before the
system is restarted. A properly sized anticipator should
maintain room temperature within 1 1/2 to 2 degree range.
The anticipator is supplied in the thermostat and is not to be
replaced. If the anticipator should fail for any reason, the
thermostat must be changed.
S-3 Heating Anticipator
The heating anticipator is a wire wound adjustable heater
which is energized during the "ON" cycle to help prevent over-
heating of the conditioned space.
The anticipator is a part of the thermostat and if it should fail
for any reason, the thermostat must be replaced. See the
following tables for recommended heater anticipator setting
in accordance to the number of electric heaters installed for
BHA & BCA models.
EHK "A" HEATER KITS
NO. OF HEAT
STRIPS
0123 4 5 6 7
HEATER KW 0 4.8 7.2 9.6 14.4 19.2 24 28.8
FIRST STAGE 0.4 0.6 0.6 0.6 0.8 0.9 0.9
BBA & BBC air handlers use EHK "B" or "C" series heater
kits. EHK "B" & "C" series heater kits are control by an elec-
tronic control board. The anticipator setting for these models
should be set to 0.12 regardless of the amount (KW) of heat
installed.
S-4 CHECKING TRANSFORMER AND CON-
TROL CIRCUIT
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 Electrical Power Supply:
1. Remove control panel cover or etc. to gain access to trans-
former.
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 con-
trol 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 inter-
ruption will break circuit (R
1
to Y
1
) for approximately three
minutes before resetting.
WARNING
Disconnect Electrical Power Supply:
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.