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5322625-UIM-A-0417
20
Johnson Controls Unitary Products
The unit is equipped with a safety package. The refrigeration system
will be protected against high refrigerant pressure and a loss of charge
switch. If either of these safety switches open, the unit will be shut off
for the 5 minute anti-short cycle time. Once this has expired, a six hour
elapsed run timer begins. If a second opening of a safety switch occurs
during this six hour period, the compressor will be locked out.
Resetting the lockout function is accomplished by:
1.
Removing power from the control's thermostat 1st stage (Y) input for
longer than 2 seconds.
2.
Removing power from “R” for more than 2 seconds.
3.
Shorting the “TEST” pins together for more than 2 seconds while
“Y” is energized.
4.
Shorting the “TEST” pins together for more than 5 seconds while
“Y” is de-energized.
GAS HEATING SEQUENCE OF OPERATION
Heating
The control board begins a call for heat when “W1” is energized (con-
nected to “R”).
The control checks to see if the pressure switch is open. If the pressure
switch is closed, the control board flashes “2” on the LED and waits
indefinitely for it to open. When the pressure switch is sensed as open,
the control begins pressure switch proving period. If the call for heat is
removed, the control goes back to Standby.
The unit control contains a built in 2
nd
stage heating “HI HEAT DELAY”
jumper that can automatically stage up to full capacity heating operation
based on first stage heating call timing. Built in heating stage up selec-
tion is a “OFF,” “10,” “15,” or “20” minute timer. Based on “HI HEAT
DELAY” jumper selection, the control is automatically staged up to high
heat during a call for low heat on the “W1” input terminal. This timing
starts over with each new call for heat. Regardless of “HI HEAT DELAY”
jumper setting if anytime the control is operating in low heat (W1) and a
24 VAC signal is received on the high heat input (W2), the control is
staged up to full capacity heating operation. When using the built in “HI
HEAT DELAY” feature and the control has staged up to full capacity
heating, the unit remains in full capacity heating until the call for heat on
the “W1” input is terminated. If using a two stage heating thermostat,
set the “HI HEAT DELAY” jumper to the “OFF” position.
Pressure Switch Proving
The control board energizes the induced draft motor and waits for the
pressure switch to close. When the pressure switch closes, the control
begins Pre-purge period. If the call for heat is removed, the control de-
energizes the inducer without post-purge and returns to standby.
If the pressure switch does not close within 5 seconds of inducer ener-
gizing, the control board flashes “3” on the LED. If the pressure switch
does not close within 60 seconds of inducer energizing, the control
shuts off the inducer for 60 seconds, then energizes the inducer for
another 60 seconds in an attempt to close the pressure switch. This
cycle continues indefinitely until either the pressure switch is proved
closed, or the call for heat ends.
Table 16:
Defrost Control Test Pins
Test Pin Shorted
With Y Call
Without Y Call
greater than 2 sec
Bypass ASCD
Display error codes
greater than 5 sec
Forced defrost
Clear error codes
Table 17:
Defrost Control Fault Codes
Description
STATUS LED
High -pressure switch fault (not in lockout yet)
2 Flashes
System in high-pressure switch lockout (last mode of
operation was normal compressor)
3 Flashes
System in high-pressure switch lockout (last mode of
operation was defrost)
4 Flashes
System in loss of charge switch lockout (last mode of
operation was normal compressor)
5 Flashes
Low Voltage (<19.2VAC) preventing further relay
outputs for > 2 seconds
6 Flashes
Low Voltage (<16VAC) stopped current relay outputs
for > 2 seconds
7 Flashes
Liquid Line sensor failure (Open or Shorted)
8 Flashes
Outdoor ambient sensor failure (Open or Shorted)
9 Flashes
Control Failure
10 Flashes