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Processor Module(s) (PSIO)
INPUTS — Each input channel has 3 terminals; 2 are used.
OUTPUTS— Output of the PSIO module is 24 vdc or
4 to 20 mA dc. There are 3 terminals; 2 are used.
REPLACING DEFECTIVE PSIO MODULES — The re-
placement part number is printed on a label on the front of
the PSIO module. The replacement module order is config-
ured as a generic replacement module, which will require
configuration in the field.
Before any service work is started, be sure that all elec-
trical disconnects are open and tagged.
Installation
1. Verify the existing PSIO module is defective by using
the procedure described in the Control Modules section
on this page.
2. Refer to the Start-Up Checklist on pages CL-1 through
CL-4 that should have been completed at start-up. This
information is needed later in this procedure. If the check-
list does not exist, make a new checklist by filling out
the and configurations on paper. Tailor
the various options and configurations as needed for this
particular installation.
3. Check that all power to the unit is off. Switch off all
circuit breakers. Carefully disconnect all wires from the
defective module by unplugging the 6 connectors. It is
not necessary to remove any of the individual wires from
the connectors. Remove the green ground wire.
4. Remove the PSIO module mounting screws and remove
the module from the control box. Save the screws.
5. With a small screwdriver, set the address switches S1
and S2 on the new PSIO module to match those on the
defective module.
6. Mount the new module in the control boxusing the screws
saved in Step 4.
7. Reinstall all 6 wire connectors and the green ground wire.
8. Check all wire connections before restoring power to
the unit.
9. Verify that the unit ON/OFF switch is in the ON
position.
10. Restore power to the unit and close the control circuit
breaker (CCB). Verify that the red and green LEDs re-
spond as described in the Control Modules section on
this page. The HSIO keypad should begin its rotating
display.
11. Using the HSIO keypad and display module, press
to verify that the software version matches the version
number shown on the PSIO label.
12. Press to verify that the factory configuration
codes agree with the values listed in Table 24 on
page 37.
13. Set other applicable inputs required in and
to match the options and accessories installed on the
equipment.
14. Enable data reset function to store all data. The HSIO
ENTER
keypad display will blank out after pressing the key
while displaying data reset (DTRS). The rotating dis-
play returns when the data reset has been completed.
15. Press and verify each item is now configured
as needed for this particular installation. Verify the fac-
tory default settings for both a specified unit and
generic control unit.
16. Press to check the remainder of the user con-
figuration values.
17. After completing the configuration steps outlined above,
close all remaining circuit breakers and perform a unit
test.
18. Complete this procedure and restore the unit to normal
operation by returning the STANDBY/RUN mode to
STBY NO.
High-Voltage Relay Modules (DSIO1 and DSIO2)
INPUTS — Inputs on terminal strip J3 are discrete inputs
(on/off). When 24 vac is applied across the 2 terminals in a
channel, it reads as an on signal. Zero v is read as an off
signal.
OUTPUTS — Terminal strips J4 and J5 are internal relays
whose coils are energized by a signal from the microproces-
sor. The relays switch the circuit to which they are con-
nected. No power is supplied to these connections by the
DSIO module.
DSIO REPLACEMENT — Beforeany service work is started,
be sure that all electrical disconnects are opened and tagged.
Installation
1. Verify the existing DSIO module is defective by using
the procedure described in the Control Modules section
on page 53.
2. Check that all power to the unit is off. Switch off all
circuit breakers. Carefully disconnect all wires from the
defective module by unplugging the connectors. It is not
necessary to remove any of the individual wires from
the connectors. Remove the green ground wire.
3. Remove the DSIO module mounting screws and re-
move the module from the control box. Save the screws.
4. With a small screwdriver, set the address switches S1
and S2 on the new DSIO module to match those on the
defective module.
5. Mount the new module in the control boxusing the screws
saved in Step 3.
6. Reinstall all of the wire connectors and the green ground
wire.
7. Carefully check allwire connections before restoringpower
to the unit.
8. Verify that the unit ON/OFF switch is in the ON
position.
9. Restore power to the unit and close the control circuit
breaker (CCB). Verify that the red and green LEDs
respond as described in the Control Modules section
on page 53. The LID (keypad) should begin its rotating
display.
10. After completing the configuration steps outlined above,
close all remaining circuit breakers and perform a unit
test.
11. Complete this procedure and restore the unit to normal
operation by returning the STANDBY/RUN mode to
STBY NO.
Refrigerant Feed Components — Each refrigerant
circuit (2 per unit) has all the necessary refrigerant controls.
Thermostatic Expansion Valve (TXV) — On 48/
50MP units, each circuit has 2 TXVs on which superheat
may be adjusted if absolutely necessary.
The TXV is set to maintain 10 to 13 F superheat leaving
the evaporator coil. It controls the flow of refrigerant to the
evaporator coils.
54