On the display
The panel prints the message as High Ambient Temp. In the manual's sample display it appears as HIGH AMBIENT TEMP on the unit screen, shown as UNIT YYYYYYYY / HIGH AMBIENT TEMP / UNIT YYYYYYYY. The message is present only during the time when the ambient temperature is causing a fault condition, so it clears from the display as soon as the condition ends.
What it means
High Ambient Temp is a unit protective fault: the chiller shuts down when the ambient (outside air) temperature rises above 130°F. The shutdown is a controlled ramped shutdown; in this model's compressor shutdown control table the fault calls for a Ramped shutdown when Soft Shutdown is disabled and a Soft Ramped shutdown when Soft Shutdown is enabled. The fault cannot cause a lockout. Independently of the shutdown, the unit is inhibited from starting any time the temperature is above 128°F, so on a hot day this message can also be the reason a stopped chiller does not restart.
Why it appears
- The ambient temperature is above the maximum operating limit (the shutdown point is 130°F).
- The ambient sensor is defective.
What to check
- Check the outside air temperature.
- Check the panel display against a thermometer reading of the ambient temperature at the sensor, to determine whether the ambient sensor is defective.
Setpoints and thresholds
- Shutdown point: the chiller shuts down when the ambient temperature rises above 130°F.
- Restart point: automatic restart, if demand allows, when the temperature falls 2°F below the cutout (128°F).
- Start inhibit: the unit is inhibited from starting any time the temperature is above 128°F.
Reset and restart
No reset action is described, and none is needed: the fault cannot cause a lockout. Restart occurs automatically, if demand allows, once the ambient temperature has fallen 2°F below the cutout to 128°F, and the message itself disappears once the ambient temperature is no longer causing the fault condition.
Questions engineers ask
What does High Ambient Temp mean on a YORK YCAV?
The chiller has shut down because the ambient temperature rose above 130°F. It performs a controlled ramped shutdown, and this fault cannot cause a lockout.
At what temperature does the YCAV trip and restart on High Ambient Temp?
It shuts down above 130°F. Restart is automatic, if demand allows, when the temperature falls 2°F below the cutout to 128°F.
How do I clear a High Ambient Temp fault on a YCAV?
No reset is required. The message is present only while the ambient temperature is causing the fault condition, so it clears by itself once the condition ends.
Why will my YCAV not start on a hot day?
The unit is inhibited from starting any time the temperature is above 128°F. If the panel reading looks wrong, compare it with a thermometer at the sensor, because a defective ambient sensor is the other listed cause.
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