Clutch Control; Servicing Alternator - Carrier Supra 950MT Operation & Service Manual

1. Disconnect the three capacitors that are connected to the three phases as these will change the readings
for some of the tests. Do not reconnect the capacitors until testing is complete. Inspect and tighten all con-
nections at the contactor, overload, standby motor, and fuse block before proceeding with this test proce-
dure. The unit must be turned off at the end of each test and turned back on at the beginning of the next test.
Prior to unit serial number MFY91192543, the buzzer and flash circuit will energize at the same time.
For unit serial number MFY91192543 and later, the flash circuit will energize before the buzzer sounds
and will drop out when the buzzer sounds.
2. The unit will energize the flash circuit for five seconds while the microprocessor performs a self-test or while
the buzzer is sounding, depending on the serial number range of the unit.
3. Place a DC AMP clamp on the T2 wire between the motor overload and the standby motor. With the flash
circuit energized there should be approximately 1.5 to 2.5 amps.
4. Check the VDC at the T2 wire between the motor overload and the standby motor. With the flash circuit
energized there should be approximately 0.5 to 0.9 VDC.
If the amp readings and voltage readings are within specs, the flash circuit is functioning. If not, continue
with the rest of the test procedure.
A meter with low resolution and/or slow reaction speed may affect the ability to read the amperage.
5. Remove fuse 28.
6. With the flash circuit energized, connect a VDC meter between ground and terminal (B) of fuse 28 (fuse
removed). This tests the voltage going to the shunt. There should be battery voltage.
7. Install fuse 28.
8. With the flash circuit energized, connect a VDC meter between ground and terminal (B) of fuse 28 (fuse
installed). This tests the voltage going to the shunt. There should be 0.5 to 0.9 VDC.
9. Remove fuse 33.
10. With the flash circuit energized, place the VDC meter between the ground and terminal (A) of fuse 33 (with fuse
removed). This tests the voltage from the shunt through the standby motor. There should be battery voltage.
11. With the unit off, check for continuity between terminal (B) of fuse 33 and the ground stud. There should be very
low resistance.
12. Reinstall fuse 33.
13. Reconnect the three capacitors connected to the three phases.
14. Remove Lockout/Tagout of the starter.
15. Verify that the unit operates correctly.
5.2.8

Clutch Control

a. Engagement Speed
The clutch is designed to engage around 900 rpm. This engagement speed will increase with shoe wear. It is cru-
cial to replace shoes before engagement speed reaches around 1600 rpm to avoid clutch burnout.
b. Shoe Wear
1 Observe clutch housing to check for any discoloration of the metal surface, which is a sign that the clutch has
overheated. If this is the case, check the condition of the shoes.
2 Remove clutch cover plate, and using a mirror, observe shoe condition and lining material thickness. If thickness
is less than 1 mm, replace shoes.
5.2.9

Servicing Alternator

Inspection
Verify tightness of connections especially for the excitation wire. If disconnected, the unit will display ALT AUX and
battery will not reload during unit operation. Check at 1500 hours or next service interval.
NOTE
NOTE
5-7 62-11863