General troubleshooting
Table 6: Troubleshooting
Problem Possible cause and correction Verification
Controller is OFF.
• Transformer has tripped:
•
Power is at Primary
of Transformer, 0V at
Secondary.
• Breaker/Fuse has tripped:
• Power is at Primary of
Transformer, 24V at
Secondary, 0V at Fuse/
Breaker.
Cause:
1. Transformer is shorted.
2. 24 VAC powered sensor
is not wired with the same
polarity as the controller.
3. SA Bus device is not wired
with the same polarity as
the controller.
Correction:
1. Ensure polarity of ~24 V
COM / ICOM / + 15VCOM/SA
BUS COM on the controller,
auxiliary devices, and I/O is
the same.
2. Ensure OUT1-OUT3
terminals of binary outputs
are not connected to ~24
VAC COM, and verify that
OCOM1-OCOM3 are not
connected to ~24 VAC
HOT (these terminals are
internally sourced).
3. Verify the short circuit has
been resolved with an ohm-
meter.
4. Reset the breaker/fuse or
replace the transformer.
Note: When replacing
the transformer, it is
recommended to replace
with a model that utilizes a
resettable circuit breaker.
A circuit breaker makes
solving wiring problems
easier.
1. Disconnect the Secondary
of the 24 VAC transformer.
2. Use an ohm-meter to
measure between ~24 V
HOT and COM; there must
be no short circuit.
Note: Some installations
require the Secondary
of the Transformer to be
Earth Grounded. If this is
the case, verify that the
Earth Ground connection
is valid and not shared
between multiple pieces of
equipment.
F4-CVM VAV Terminal Equipment Controllers Installation Instructions28
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