JOHNSON CONTROLS
15
FORM ET130.13-NOM3 (708)
ECM SPECIFIC TROUBLESHOOTING GUIDELINES
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
Motor Fails to Start
CFM Adjustment voltage above 9.9
VDC or below 5.1 VDC
Properly adjust CFM voltage.
ECM cables improperly seated at motor
Unplug cables from motor and re-install, making sure
plugs on cables are fully seated in motor receptacles.
ECM cables open or intermittent Replace cable(s). See section on checking cables below.
Mechanical failure Check motor and confi rm it rotates freely.
Electrical failure Replace motor.
Fan Relay Contacts Oxidized/Sulfi dized Replace fan relay.
Motor Surges
Fan CFM adjustment voltage outside
range of Fan Calibration Curve
Adjust voltage to value within range of Fan Calibration
Curve.
ESP (external static pressure) too high
Verify balancing dampers as open as possible (at least
one should be fully open). Verify radiated sound damper
(if supplied) swings freely. Verify plenum opening is un-
obstructed. Verify fi lter (if supplied) is not dirty and does
not obstruct fl ow of plenum air.
Excessive Motor
Noise
Motor mounting bolts loose Tighten motor mounting bolts.
Fan wheel rubbing on fan housing Align wheel in housing.
Loose fan wheel Align and tighten.
Poor Performance
Lack of required external static pressure Add required external static pressure.
Wrong Program Contact Factory.
Motor Runs in
Reverse, Doesn’t
Respond to Speed
Adjustment
Motor Failure Replace.
Checking ECM Cables
Remove power from the unit. Unplug signal cable at
motor, but leave quick connects attached to ETPWM
board and fan relay or quick connect terminal block (see
Figure 3 and 4). Use ohmmeter to check continuity.
Repeat process for three wire power cable if signal cable
does not appear to be defective (see Figure 3 and 5).
Only very light force is required when
inserting meter probe into plug. Ex-
cess force will damage contacts.
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