Trane VAV-UCM 4.2, Инструкция по установке и обслуживанию

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VAV-SVX01C-EN 63
Troubleshooting
Wired Zone Setpoint Failure Procedures
In the event that the UCM reports an incorrect zone setpoint, properly inspect the following:
1. Zone sensor setpoint wired incorrectly
• Check wiring for the correct connections. See Chapter 2 for further details on zone sensor
wiring.
2. Defective zone sensor setpoint dial
• Disconnect the zone sensor terminal connections from the UCM and using an Ohmmeter,
measure the resistance across the terminals 2 (common) and 3 (setpoint) of the zone sensor.
Compare the resistance to specified set point on sensor using
Table 3, p. 11 . The resistance
shown should correlate within ± 2 degrees of setpoint shown on Table 3, p. 11 If not, the zone
sensor needs to be replaced.
3. Defective wiring or UCM
• With wires still connected to VAV UCM, disconnect zone sensor setpoint wires and check
voltage (DC) from wires that were connected to terminals 2 and 3 of zone sensor. These
should measure 5VDC. If meter does not read 5VDC then see if the VAV UCM is outputting
5VDC. This can be done by disconnecting the wires on the VAV UCM on terminals TB3-2 and
TB3-3 and measure the VDC. It should be 5VDC. If 5VDC is shown on terminals TB3-2 and
TB3-3 at the UCM the wires going to the zone have an open. If 5VDC is not present check
incoming power to the UCM board on TB1-1 and TB1-2. This should measure 24 VAC ± 10%.
If you measure the proper voltage at TB1-1 and TB1-2 and no voltage at TB3-2 and TB3-3
replace UCM.
Note: If no voltage at TB1-1 and TB1-2 see UCM see UCM failure procedures.
4. Zone sensor setpoint is shorted out
• Check the resistance across the wires. Disconnect wires from UCM and zone sensor making
sure the ends are not touching each other and measure resistance. It should be infinity or
no conductivity. If lower resistance is shown wires are shorted together and needs to be
replaced.
5. More than one UCM connected to a single zone sensor
• Cut jumper wires (W1 and W2) on all slave units. If jumper is not cut it will give erroneous
temperature setpoint value.
75
76
77
78
79 403
383
364
344
325 10.4
10.2
10.0
9.7
9.5
80
81
82
83
84
85 306
286
267
247
228
208 9.3
9.0
8.8
8.6
8.4
8.2
Note:
Thumbwheel resistance checks are made at terminal 2 and 3 on the zone sensor. Temperature sensor resistance is
measured at terminal 1 and 2 of the zone sensor.
Table 14. Zone sensor temperature resistance (continued)
Temp (
o
F) Thermostat Thumbwheel
Resistance (Ohms)
Sensor Resistance (k Ohms)