Defrost Control Components; Timing Pins 30(T1), 60(T2), 90(T3); Timing Jumper; `24V' Terminal - Lennox HP22-261 Service Manual

SOLID STATE DEFROST TIMER
TROUBLESHOOTING

TIMING JUMPER

TIMING PINS
FIGURE 9
The control contains a solid state timer which switches an
external defrost relay through 1/4" male spades mounted
on the control's circuit board. When the defrost thermo
stat closes (call for defrost), the defrost timer initiates a
30, 60 or 90 minute (depending on how the control is pre
set) timing seqeunce. If the defrost thermostat remains
closed when the timing sequence ends, the defrost relay
is energized and defrost begins.

Defrost Control Components

1- Timing Pins 30(T1), 60(T2), 90(T3)

Each of these pins provides a different timed interval
between defrosts. A jumper connects the pins to cir
cuit board pin W1. Table 3 shows the timings of each
pin. The defrost interval can be field changed to 30,
60 or 90 minutes. The defrost period (14 minutes)
cannot be changed. To change the interval between
defrosts, simply remove the jumper from the pin it is
connected to and reconnect the jumper to one of the
other available pins (see figure 10).
2- Timing Jumper
The timing jumper is a factory installed jumper on the
circuit board used to connect pin W1 to one of the
three timing pins. The jumper may be connected to
any one of the timing pins but must never be con
nected to either of the `TST' pins. See Caution.
PINS
CONTROL
TERMINALS
DEFROST
CONTROL CMC
TIMINGS
30 (T1)
NORMAL 30 + 3
OPERATION
`TST' PINS
7 + 0.7
JUMPERED
TOGETHER
CAUTION - DO NOT CONNECT TIMING JUMPER TO
EITHER `TST' PIN. `TST' PINS ARE USED ONLY DUR
ING A TEST AND MUST NOT CONNECT WITH ANY OF
THE TIMING PINS. CONTROL DAMAGE WILL RE
SULT.
WARNING - AVOID CONTACT WITH OTH
ER CONTROL TERMINALS OR CONTROL
COMPONENTS.
NEEDLE-NOSE
PLIERS
WARNING - DO NOT CONNECT TIM
ING JUMPER TO EITHER `TST' PIN.
TO CHANGE CONTROL TIMINGS:
1- Turn off all power to the unit to avoid damaging the circuit
board.
2- Grasp wire connector firmly with needle nose pliers as shown.
3- Gently pull connector from pin.
4- Select new timing pin. DO NOT SELECT A `TST' PIN.
5- Gently push connector onto desired pin (see Table 3 for tim
ings). Connector is seated when pin snaps.
6- Turn on power to unit.

3- `24V' Terminal

Terminal `24V' receives 24VAC from the control trans
former through the defrost thermostat. This terminal
powers the control's internal timer and relays. Termi
nal `24V' is powered only when there is a call for de
frost (defrost thermostat closed). The timer begins
timing at 0 only after terminal `24V' receives power.
Page 7
TABLE 3
INTERVAL BETWEEN
DEFROSTS WITH
JUMPER CONNECTED TO:
60 (T2) 90 (T3)
60 + 6 90 + 9
MIN. MIN. MIN.
14 + 1.4 21 + 2.1
SEC. SEC. SEC.
FIGURE 10
DEFROST
TIME
14 + 1.4
MIN.
3.3 + 0.3
SEC.