ClimaCool UGW Manual - Manual (Page 53)

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Refrigeration System Re-Processing and Charging
Test the Valve
The resistance of the motor winding may be tested without
opening the system .
1 . Remove power from the external controller and/or
interface board .
2 . Remove the valve leads from interface board .
3 . Measure the resistance between the black and white
leads of the valve . Resistance should be 75 ohms with
the valve at room temperature or approximately 65 ohms
if the valve is at -40°F .
4 . Measure the resistance between the green and red leads .
This value should be within ± 5% of the resistance between
the black and white leads .
5 . Measure the resistance from any lead to valve body .
Resistance should be infinite, that is to say, open.
Test the Interface Board
The flow charts on the following page are designed to
assist in diagnosing a possible interface board failure . All
measurements should be made with a Digital Multimeter .
Troubeshooting Guide - Interface Board Operating on External Signal (4-20 ma or 0-10 VDC)
Note: Before testing the interface board, make certain the valve is operating . See “Test the Valve” instructions .
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
1. Is there 24V AC at terminals 24V + 24V-?
Repair or replace power supply or power supply
wiring .
Check wiring for polarity . Transformer should
NOT be a grounded secondary type . Replace if
necessary .
Replace the transformer with an isolated
secondary type .
Shut off power to interface board and correct
wiring .
Test the step motor . If operational, replace the
interface board .
Test the step motor . If operational, replace the
interface board .
Shut off power to interface board and external
controller . Correct input signal observing polarity .
Test or replace external controller .
Shut off power to interface board and external
controller and correct wiring .
Shut off power to interface board and external
controller and move pin jumper to correct
location .
First make sure input at terminal +4-20 & -4-20 is
greater than 4 ma . If so, repair wiring or replace
pumpdown relay .
Test the step motor . If operational, replace the
interface board .
Interface board if defective . Replace interface
board .
2. Is the fuse insalled and intact?
3. Is the 24V transformer of the isolated secondary type?
4. Is the valve connected to terminals (black, white, green,
red) with wire colors correct?
5 . Connect voltmeter on AC scale to the Black and White
valve terminals . Interrupt and restore power to the
interface board. Does the meter read 12-14 volts AC?
6 . Repeat above test using Red and Green terminals . Does
the meter read 12-14 volts?
7. Are wires for external signal connected to terminals +4-20
& -4-20?
8. Is external signal present? Signal should be 4-20 MA at 12
volts DC or 0-10 VDC .
9. Is polarity of signal correct? (+) to term +4-20 and (-) to
term -4-20 .
10. Is pin jumper for input signal selection (CN4 or CN2) on
the correct pins? See Figure 18*.
11 . If present, remove wires from pumpdown terminals IN &
GND. Did the valve open?
12 . Put a jumper across terminals IN & GND . Did the valve
close?
13 . Remove the jumper from terminals IN & GND and
reconnect the wires .
14 . Remove the pin jumper from CN4 or CN2 . Did the valve
close?
Interface board is functional, test external controller
*Note: CN4 provides 3 levels of input impedence to match external controller outputs . Be sure controller output and interface board
inputs are matched .