Time-Delay Relay - Carrier R-22 Application Manual And Service Manual

OPERATING
TIME
T1
_
T2
BLK DENOTES CLOSED CONTACTS
HN67ZA002
Y YEL
TERMINAL
BOARD
CONNECTION
heater. Carefully feel area around crankcase heater. If warm,
crankcase heater is probably functioning. Do not rely on this
method as absolute evidence heater is functioning. If compressor
has been running, the area will still be warm.
With power off and heater leads disconnected, check across leads
with ohmmeter. Do not look for a specific resistance reading.
Check for resistance or an open circuit. Change heater if an open
circuit is detected. Some crankcase heaters in this series of units
are equipped with a crankcase-heater switch. This energy-saving
device shuts off power to heater when temperatures are high
enough that heater is not needed. Be sure this switch is functioning
normally before condemning crankcase heater.
Step 6—Time-Delay Relay
The time-delay relay (TDR) is a solid-state-controlled, recycle-
delay timer which keeps the indoor blower operating for 90 sec
after thermostat is satisfied. This delay enables the blower to
remove residual cooling in the coil after compression shutdown,
thereby improving the efficiency of the system. The sequence of
operation is that on closure of the wall thermostat and at the end of
a fixed on-delay of 1 sec, the fan relay is energized. When the
thermostat is satisfied, an off-delay is initiated. When the fixed
delay of 90 ± 20 sec is completed, the fan relay is de-energized and
fan motor stops. If the wall thermostat closes during this delay, the
5 MIN
Fig. 16—Cycle-Protector Sequence
CUT YELLOW WIRE
BETWEEN CONTACTOR AND
LOW-PRESSURE SWITCH
SAFETY
YEL
CONTROL
YEL
T1
Fig. 17—Cycle-Protector Wiring
3
SEC
T1
_
T2
BLK DENOTES CLOSED CONTACTS
HN67PA025, HN67ZA003, HN67ZA008
A91436
YEL
VIO
LOGIC T3
T2
Fig. 18—Wiring for Single-Pole Contactor
TDR is reset, and the fan relay remains energized. The TDR is a
24v device that operates within a range of 15 to 30v and draws
about 0.5 amps.
If the blower runs continuously instead of cycling off when the fan
switch is set on AUTO, the TDR is probably defective and must be
replaced.
17
OPERATING
5 MIN
TIME
C BRN C
TERMINAL
BOARD
CONNECTION
BLK
DSV
CH
11 21
A91437
A88415
A91426