ENVIRO-TEC
34
FORM ET115.24-NOM4 (819)
SECTION 2 - START-UP
PROBLEM
POSSIBLE CAUSE
CORRECTIVE ACTION
Motor speed cannot be adjusted
PWM board error or faulted
Refer to
PWM Board Status LED on page
25
. Verify all connections. Push reset
button. Replace board if fault returns.
Improper wiring connections
Verify wiring. If Fan Coil Relay board
present, verify all jumpers installed.
EC wiring harness damaged or
improperly seated
Unplug harness and re-install, making
sure plugs are fully seated. See section
on
Checking EC Wire Harnesses on page
35
. Replace harness if damaged.
No control signal (constant airflow
and constant torque)
Constant airflow and constant torque EC
motors will run at idle speed if they lose
PWM signal while enabled.
Verify PWM signal at motor connector
by connecting a multimeter set for “duty
cycle” between pins 1P1 and 1C (or
between pins 2P1 and 2C). The duty cycle
represents the on-time percentage signal
sent to the motor (this number will vary
between the minimum and maximum duty
cycle set by the factory). See
Figure 12 on
page 25
for PWM board connections.
Refer also to
PWM Board Status LED on
page 25
to verify board is in normal
operating mode.
ESP (external static pressure) too
high
Verify dampers, if present, are not closed.
Verify there are no obstructions in the
discharge ductwork and/or at the plenum
opening. Verify filter is not dirty and does
not obstruct airflow.
Motor driver failure
Replace motor (constant airflow or
constant torque motors)
Replace driver (constant RPM motors)
Motor runs in reverse, does not respond
to speed adjustment
Motor driver failure
Replace motor (constant airflow or
constant torque motors)
Replace driver (constant RPM motors)
Excessive motor noise
Motor mounting bolts loose
Tighten motor mounting bolts.
Motor bearing
Replace motor.
Motor overloaded
Use amp meter to verify motor amps.
Verify motor rotates freely with power
disconnected. If not, replace motor. Verify
static pressure within limits shown on Fan
Calibration Curve on unit.
Fan wheel rubbing on fan housing
Align wheel in housing.
Loose fan wheel
Align and tighten.
Motor runs in G3 PWM Program mode
but not in Run mode
Loose pin in Fixed Speed Conn.
harness
Verify that the pins in the Fixed Speed
Conn. harness (see location in
Figure 12
on page 25)
are inserted fully.
TABLE 2
- EC MOTOR TROUBLESHOOTING GUIDELINES (CONT'D)
Summary of Contents for VHA
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Page 78: ...ENVIRO TEC 78 FORM ET115 24 NOM4 819 SECTION 6 Dimensional Data NOTES ...