32 | uponorpro.com
Symptoms and solutions
Symptom
Look for…
Corrective action
LCD display is off
Power to control
Use electrical meter to measure 24 VAC voltage on input
power R and C terminals.
System pump
always on
Display shows idle Idle operation requires that the system pump operate
continuously while below the melting temperature setting.
Blue short
Dirt or salt on
sensor
The sensor requires regular cleaning. Avoid using road
salt on the snow melting slab.
Slab is above melt
temperature
Slab target
The slab is heated to the slab target.
Heat on not shown Check wiring of the system pump. The system pump
operates continuously during melt and idle operation.
The heat source must be wired to operate together with
the heat relay.
System running
with no snow
Idle
Idling heats the slab when the temperature falls below
the Idle temperature.
Melt
During Cold Weather Cut Out (CWCO), the system
is shut off. If shut off during a melt cycle, the system
resumes melting once the outdoor temperature is above
CWCO.
Timed melt
System manually started.
Snow on slab but
system did not start
Off
System has been manually stopped and the Pavement
Snow and Ice Sensor or the Aerial Snow Sensor never
dried, thereby preventing the system to automatically start.
