Troubleshooting - Trane TR-OHS RCU Series Installation, Operation And Maintenance Manual

Maintenance

Troubleshooting

WARNING
Hazardous Service Procedures!
Failure to follow all precautions in this manual and on
the tags, stickers, and labels could result in death or
serious injury. Technicians, in order to protect
themselves from potential electrical, mechanical, and
chemical hazards, MUST follow precautions in this
manual and on the tags, stickers, and labels, as well as
the following instructions: Unless specified otherwise,
disconnect all electrical power including remote
disconnect and discharge all energy storing devices
such as capacitors before servicing. Follow proper
lockout/tagout procedures to ensure the power can not
be inadvertently energized.When necessary to work
with live electrical components, have a qualified
licensed electrician or other individual who has been
trained in handling live electrical components perform
these tasks.
Symptom
Control is Erratic
Unit Fails to Start
Condensing Unit Head Pressure Too High Non-condensable gas or air in system.
Condensing Unit Head Pressure Too Low
Suction Pressure Too Low
24
Probable Cause
Wiring improperly connected or broken.
Incorrect phasing or voltage.
Power failure.
Overload protection tripped.
Low condensing unit airflow (indicated by
excessive warm air leaving the condensing unit
fan).
Overcharge of refrigerant.
Condensing unit fan not operating.
Condensing unit pressure regulating valve
setting too high.
Loss of refrigerant (indicated by high superheat,
low sub-cooling temperature and low suction
pressure).
Condensing unit fan controls not set properly. Adjust or repair controls.
Control pressure set too low.
Loss of refrigerant (excessive bubbles in sight
glass).
Expansion valve stuck or obstructed (short cycle
or continuous running).
Clogged drier/strainer (feels cold).
Dirty air filters.
Recommendation
Check wiring against electrical drawing.
Correct phase or voltage input.
• Check power source, power inlet and fuses.
• Check control cables and connections.
Check for cause of overload and re-set circuit
breaker(s) or motor starter protector(s).
Recover system, evacuate per
System for Charging," p. 15 and recharge.
Install new drier/strainer.
Open air passages. Clean coil. Check condensing
unit fan(s).
Reclaim excess refrigerant from system.
• Check main voltage power source to unit.
• Check fan motor starter protector,
contactor, fan cycling switch or fan speed
controller.
• Check pressure/temperature operating
switches and motor. Replace as needed.
Adjust to obtain correct pressure.
Locate and repair leak. Recharge system.
R407C- Readjust to 320 psig.
Locate leak and repair. Recharge system.
Remove and clean or replace valve.
Replace with new drier/strainer.
Clean/replace filters on AHU.
"Preparing
SS-SVX004C-EN