On the display
The micro panel shows Low Ambient Temp as a unit fault. A sample line on the display is UNIT YYYYYYYY LOW AMBIENT TEMP, and in the fault history it appears as UNIT FAULT LOW AMBIENT TEMP. The message is present only during the time when the ambient temperature is causing a fault condition.
What it means
If the ambient temperature falls below the programmable Low Ambient Temp Cutout, the chiller shuts down with a controlled ramped shutdown. With soft shutdown disabled the shutdown type is Ramped; with soft shutdown enabled the fault performs a Soft Ramped shutdown. The fault occurs only if the Low Ambient Cutout is set to ENABLED under the OPTIONS key. The fault and inhibit code table lists it as code 1, a Unit Panel fault.
Why it appears
- Ambient temperature is lower than the programmed operating limit — the shutdown is the intended protective response when the cutout is enabled.
- Ambient Sensor is defective.
What to check
- Check the programmed cutout and determine if it is programmed correctly.
- Check the panel against the thermometer reading of ambient temperature — a mismatch points to a defective Ambient Sensor.
- Review the fault history: the OPTIONS Low Ambient Temp Cutout message shows whether the low ambient cutout was enabled or disabled at the time of the fault, and the program values show the cutout programmed at that time.
Setpoints and thresholds
- Low Ambient Temp Cutout: programmable between -2.0°F (-18.9°C) and 50°F (10.0°C) with a default of 25°F (-3.9°C). It sets the outdoor temperature at which the chiller shuts down to utilize other methods of cooling.
- Low Ambient Cutout option: ENABLED or DISABLED under the OPTIONS key; the fault only occurs when the cutout is ENABLED.
- Start inhibit: the unit is inhibited from starting any time the temperature is below the cutout + 2°F.
Reset and restart
This fault cannot cause a lockout, so no manual reset is needed. The display clears once the ambient temperature is no longer causing a fault condition. Restart can occur, if demand allows, when temperature rises 2°F above the cutout.
Until then, starting remains inhibited.
Questions engineers ask
Why does my YORK YCAV shut down on Low Ambient Temp?
The ambient temperature fell below the programmed Low Ambient Temp Cutout while the Low Ambient Cutout option was ENABLED under the OPTIONS key. The chiller performs a controlled ramped shutdown, or a soft ramped shutdown if soft shutdown is enabled.
How do I clear the Low Ambient Temp message on a YCAV?
No manual reset is required — the fault cannot cause a lockout. The message clears when the fault condition ends, and the unit can restart, if demand allows, once the temperature rises 2°F above the cutout.
What is the default Low Ambient Temp cutout on the YCAV?
The default is 25°F (-3.9°C). The cutout is programmable between -2.0°F (-18.9°C) and 50°F (10.0°C).
How can I tell if the ambient sensor is defective?
Check the panel against a thermometer reading of the ambient temperature. If the panel does not agree with the thermometer, the Ambient Sensor is suspect.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YCAV; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YCAV messages: fault codes · YORK YCAV documentation · YORK manuals