Troubleshooting - McQuay M5RT 90 BR Technical Manual

Troubleshooting

For any enquiries on spare part please contact your authorized dealer. If any malfunction of the
air conditioner unit is noted, check the following fault conditions and causes for some simple
troubleshooting tips.
Problem
Unit does not run.
Compressor does not operate in
3 min after unit has started.
Air flow is low.
Compressor operate
continuously.
No cool air delivered during
cooling cycle, or no hot air
delivered during heating cycle.
On heating cycle, no air
delivered (M5RT90BR).
Or, the delivered air is not warm
enough (M5RT120BR).
If the fault persists, please call your authorized local dealer/serviceman.
Alarm Shown On The Rooftop Panel
• Whenever panel received a new alarm, an alarm message will pop up on the LCD. It shows type of alarm,
alarm occurred time and date. Backlight blinking (if backlight is not OFF) and alarms buzzer produces
beeping sound (if it's set ON).
The buzzer will beep for 10 minutes after that stop for 5 minutes (with the backlight still blinking), this
process keep looping until the alarm is dissolved or a key press is detected.
• Backlight will stop blinking via key press. Press UP or DOWN key to scroll the alarms display if more than
one alarms occurred. Press ESC to exit to the summary pages.
• If one of the alarms has been dissolved, pop up message will update its display (would not show the dissolved
alarm anymore). If all the alarms have been dissolved, it will exit to the summary pages automatically.
• If the existing alarm has not been dissolved and another new alarm is occurred, the pop up message will
update to the latest alarm.
• A sign [A] will be shown and blink in Summary Pages as long as the alarm has not been dissolved. If user
needs to view current existing alarms, press "ALARM" key in the summary pages or go to ALARM MENU
in MAIN MENU.
• The panel can display up to 20 new alarms at once (which are not dissolve yet).
• All the incoming new alarms record will be store in ALARM MENU – Show Alarms.
• The alarm histories are viewable ONLY when all the new alarm already dissolved.
• If the contact type alarm is set to manual reset, the alarm can only be dissolved by off and on back
rooftop unit.
Causes
Power failure.
Fuse blown or circuit breaker tripped.
Power supply wiring phase incorrect.
Protection against frequent starting.
Filter is filled with dust and dirt.
There are some obstacles at the air inlet
or outlet of the units.
Dirty air filter.
Temperature setting is too low (for cooling).
Temperature setting is too high (for heating).
Temperature setting is too high (for cooling).
Temperature setting is too low (for heating).
Unit is in defrosting cycle.
70
Action
Press the [ON/OFF] after power restore.
Replace fuse or reset circuit breaker.
Modify the wiring phase.
Wait for 3 min for the compressor
to start.
Clean the filter.
Remove obstacles.
Clean the air filter.
Reset the temperature.
Set the temperature lower.
Set the temperature higher.
Wait for a while.
(It will be resumed after defrosting.)