Trane VAV-UCM 4.2, Инструкция по установке и обслуживанию

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62 VAV-SVX01C-EN
Troubleshooting
• Check wiring for the correct connections. See Chapter 2 for further details on zone sensor
wiring.
3. Defective zone sensor
• Disconnect the zone sensor terminal plug from the UCM and using an Ohmmeter, measure
the resistance across the terminals 1 and 2. Compare the resistance to temperature using
Table 3. The resistance should shown value should be within ± 2 degrees near those
measured with an accurate temperature measuring device. If not, the zone sensor needs to
be replaced.
4. Defective wiring or UCM
• With wires still connected to VAV UCM, disconnect zone sensor wires and check voltage (DC)
from wires that were connected to terminals 1 and 2 of zone sensor. You should measure
5VDC. If you do not have 5VDC then see if the VAV UCM is outputting 5VDC. This can be done
by disconnecting the wires on the VAV UCM on terminals TB3-1 and TB3-2 and measure the
VDC. It should be 5VDC. If you have 5VDC 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.
Should measure 24 VAC ± 10%. If you measure the proper voltage at TB1-1 and TB1-2 and
no voltage at TB3-1and TB3-2 replace UCM.
Note: If no voltage at TB1-1 and TB1-2 see UCM failure procedures
5. Zone sensors 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.
6. 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 value.
Table 14. Zone sensor temperature resistance
Temp (
o
F) Thermostat Thumbwheel
Resistance (Ohms)
Sensor Resistance (k Ohms)
55
56
57
58
59 792
772
753
733
714 17.0
16.5
16.1
15.7
15.4
60
61
62
63
64 694
675
656
636
617 15.0
14.6
14.3
14.0
13.6
65
66
67
68
69 597
578
558
539
519 13.3
13.0
12.6
12.3
12.1
70
71
72
73
74 500
481
461
442
422 11.8
11.5
11.2
11.0
10.7