Carrier WeatherMaster 50HC04 Service And Maintenance Instructions page 5

Position 5 tap, the motor speed is approximately 1050 rpm
(17.5 r/s) but varies depending on fan wheel loading.
Selecting speed tap
The five communication terminals are each programmed to pro-
vide a different motor torque output. See Table 1. Factory default
tap selection is Position 1 for lowest torque/speed operation.
Table 1 — Motor Tap Programing
(percent of full-load torque)
50HC UNIT
TAP 1 TAP 2
SIZE
04 32
05 46
06 73
Factory Default: Tap 1 (VIO).
Selecting another speed:
1. Disconnect main power to the unit. Apply lockout/tag-out
procedures.
2. Remove the default motor signal lead (VIO) from terminal
1 at the motor communications terminal.
3. Reconnect the motor signal lead to the desired speed (ter-
minals 1 through 5).
4. Connect main power to the unit.
Motor "rocking" on start-up
When the motor first starts, the rotor (and attached wheel) will
"rock" back and forth as the motor tests for rotational direction.
Once the correct rotational direction is determined by the motor
circuitry, the motor will ramp up to the specified speed. The
"rocking" is a normal operating characteristic of ECM motors.
Troubleshooting the ECM motor
ECM Motor Testing Procedure
1. Inspect motor bearing. ECM motors have sealed stainless
steel bearings. Turn the motor shaft by hand to ensure that it
turns freely and that there is no excessive play or friction as it
rotates. Be mindful that motors have permanent magnetized
rotors, which will add a stepping feel to the shaft rotation.
2. Inspect motor windings. ECM motors have 3 electrically
identical windings. Once the motor is detached from the
module, check the winding resistance.
a. Using an Ohm meter set to the 200Ω scale, measure
resistance as follows (see Fig. 7).
Blue (A) to Black (B)
Blue (A) to Red (C)
Black (B) to Red (C)
The difference between any two leads should be less than
20 Ohms. The resistance from A to B, A to C, and B to C
should be approximately the same (should differ by a maxi-
mum of ±10%). See Fig. 8.
3. Inspect resistance to ground.
a. Measure the resistance of each lead to the unpainted
motor plate (see Fig. 9).
b. Resistance should be >100KΩ.
c. If measure resistance is outside the above range,
replace the motor.
Fig. 7 — Winding Leads
TAP 3 TAP 4
38 45 50
58 61 69
82 85 90
TAP 5
100
100
100
Fig. 8 — Testing Winding Resistance
Fig. 9 — Resistance to Ground
If the motor passes steps 1-3, then it is in good condition.
Troubleshooting the X13 ECM requires a voltmeter.
1. Disconnect main power to the unit.
2. Remove the motor power plug (including the control BRN
lead) and VIO control signal lead at the motor terminals.
3. Restore main unit power.
4. Check for proper line voltage at motor power leads BLK
(at L terminal) and YEL (at N terminal). See Table 2.
50HC UNIT
VOLTAGE
208/230
460
575
5. Using a jumper wire from unit control terminals R to G,
engage motor operation. Check for 24-v output at the
defrost board terminal IFO.
6. Check for proper control signal voltages of 22-v to 28-v at
motor signal leads VIO and BRN.
7. Disconnect unit main power. Apply lockout/tag-out
procedures.
8. Reconnect motor power and control signal leads at the
motor terminals.
9. Restore unit main power.
10. The motor should start and run. If the motor does not start,
remove the motor assembly. Replace the motor with one
having the same part number. Do not substitute with an
alternate design motor as the torque/speed programming
will not be the same as that on an original factory motor.
5
>100 KΩ
Table 2 — Motor Test Volts
MOTOR VOLTAGE
230
230
460
MIN-MAX VOLTS
190-250
210-250
420-500