Trane CVHE Troubleshooting Manual page 102

1 Disable Free Cooling in the Operator Settings menu.
2 Unplug the free cooling relay connectors from J-16 and J24 on the Options module.
3 Using a DVM, measure the resistance between J16-3 and J16-2. Record in the table below.
4 Measure and record the resistance between J16-3 and J16-1.
5 Measure and record the resistance between J24-3 and J24-2.
6 Measure and record the resistance between J24-3 and J24-1.
7 Enable Free Cooling in the Operator Settings menu.
8 Using a DVM, measure the resistance between J16-3 and J16-2. Record in the table below.
9 Measure and record the resistance between J16-3 and J16-1.
10 Measure and record the resistance between J24-3 and J24-2.
11 Measure and record the resistance between J24-3 and J24-1.
12 If any of the recorded resistances are out of the specified values, the free cooling relays are
not functioning properly.
Terminals Resistance
J16-3 to J16-2
J16-3 to J16-1
J24-3 to J24-2
J24-3 to J24-1
UCP2 provides Free Cooling control as follows:
1 The Options module shall provide the following Binary Inputs/Outputs:
~ Class II Binary Input: External Free Cooling Switch
~ Class II Binary Input: FC Actuators Closed FC valve closed limit switches are wired in series
to this input.
~ Class I Form C Binary Output: FC Actuator Relay #1 Operates first FC valve.
~ Class I Form A Binary Output: FC Aux. Relay Customers choice.
~ Class I From C Binary Output: FC Actuator Relay #2 Operates second FC valve
2 The operator has the ability to control Free Cooling On/Off manually at the Front Panel,
Automatically via a On/Off binary input (called External Free Cooling Switch) at the Options
module, and from a command from Tracer. At the binary input at the Options module, an
open shall command Free Cooling Off, and a Short will command Free Cooling On.
3 For display and mode purposes, the FC mode shall be displayed when the FC valves are
open. That is, when the FC valve relays are energized and the FC valve limit switches open
the FC mode shall be displayed. Likewise, when the FC valve relays are de-energized and
the FC valve limit switches close, the FC mode shall be terminated.
4 FC cannot be entered if the chiller is in STOP; FC can only be entered from AUTO. Either
setting the FP CLD to FC On or closing the Ext FC Switch binary input, or receiving a
CVHE-SB-32A
Free Cooling Relay Checkout
Recorded Value when Free Cooling
Less than 5 Ohms
Greater Than 1M Ohm
Less than 5 Ohms
Greater Than 1M Ohm
is Disabled
Value when Free Cooling is
Enabled
Greater Than 1M Ohm
Less than 5 Ohms
Greater Than 1M Ohm
Less than 5 Ohms
97