Checkout Procedure For Mcsp Step Load Output - Trane R Series Diagnostic Troubleshooting Repair

RLC-SVD03A-EN
Compressor Capacity
pressure, then the Slide Valve is bound.
5. If cylinder cavity pressure does not decrease or is at suction pressure
before the Unload toggle switch was closed, the problem lies with either
the solenoid coil or valve.
6. Check coil
7 . If coil checks out, change the valve.
NOTE: Refer to the Flow Chart in
Unload:
10. Manually unload compressor in short increments.
11. Does RLA Decrease?
No
12. Does Cavity Press
decrease to a level
close to suct pressure?
No
13. Does Magnetic Field on
Solenoid Coil exist?
No
14. Is wiring to valve OK?
No
15. Repair and reverify.
Figure 6 Manual Slide Valve Diagnostic Flow Chart

Checkout Procedure for MCSP Step Load Output

The MCSP controls the step load solenoid valve on the respective
compressor with a 115 VAC dry contact output relay. This differs from the
Load/Unload solenoid output, which is from a triac (solid state relay). Refer to
the Chiller Control Wiring diagrams and the Component Layout Drawings for
the following procedure.
Figure 6.
Yes
Check UCM
Bad
Replace
Yes
Slide valve mechanism bound
Yes
Solenoid valve mechanism bound
Yes
Check for open solenoid coil
Good
Stop
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