Diagnostics and Service

Diagnostics and Service

The most important aspect of troubleshooting unit ventilator controls is to isolate the source of the problem into one of two categories:

1The problem resides within the UVC.

2The problem is external to the UVC. Under most circumstances the problem is external to the UVC.

Alarm and Fault Monitoring

The UVC is programmed to monitor the unit for specific alarm conditions. If an alarm condition exists, a fault occurs. When a fault exists, the following occurs:

The UVC indicates the fault condition by displaying the fault code on the keypad/display.

The remote wall-mounted sensor (optional) LED flashes a pattern indicating that a fault condition exists.

The fault signal binary output energizes.

The fault performs the appropriate control actions as described for each fault.

Manual reset faults can be reset in one of three ways:

By cycling the unit power.

Via the keypad/display menu.

Via the network interface.

Table 22: Alarm and fault code summary

Priority

Fault description

Reset

Keypad/

display fault

 

 

 

codes

1

Space Temp Sensor Failure

Auto

F0

2

DX Pressure Fault

2-Auto in 7 days, then Manual

F1

3

Compressor Envelope Fault

2-Auto in 7 days, then

F2

 

Manual*

 

 

 

4

Discharge Air DX Cooling Low Limit Indication

Auto

F3

5

Condensate Overflow Indication

Auto

F4

6

Space Coil DX Temp Sensor Failure

Auto

F5

7

Outdoor Temp Sensor Failure

Auto

F6

8

Discharge Air Temp Sensor Failure

Auto

F7

9

Water Coil DX Temp Sensor Failure

Auto

F8

10

Water-out Temp Sensor Failure

Auto

F9

11

Space Humidity Sensor Failure

Auto

FA

12

Outdoor Humidity Sensor Failure

Auto

Fb

13

Space CO2 Sensor Failure

Auto

FC

14

Not used

 

Fd

15

Not used

 

FE

16

Change Filter Indication

Manual

FF

17

EPROM Memory Indicator

Replace conroller board

EE

18

Configuration Display

Download file

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* Rev 1_27 has auto reset

McQuay OM 751

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American Standard UV05 Alarm and Fault Monitoring, Alarm and fault code summary, Priority Fault description Reset Keypad