Randell uHi

What does Randell uHi mean?

On a Randell prep table with the Danfoss controller, uHi is the Line Voltage Too High alarm. The Danfoss controller monitors supply voltage and will alarm when the incoming line voltage rises above its acceptable range. Operating outside the rated voltage can harm the compressor, and the manual warns that exceeding voltage limits can void the warranty.

Symptoms

• Display shows uHi with the alarm LED lit
• Unit may not run or the compressor may not receive output
• Other equipment on the same supply may show voltage issues
• Cabinet temperature may rise while the alarm is active

Common causes

• Incoming line voltage above the unit's rated range
• Supply voltage fluctuating beyond plus or minus 10 percent of the data-tag value
• Shared or improperly wired circuit instead of a dedicated line
• Building power supply problem

Diagnostic steps

1. 01

   Confirm the alarm

   Verify the Danfoss display reads uHi, the Line Voltage Too High alarm.

2. 02

   Verify the power source voltage

   The Danfoss table directs verifying the voltage of the power source; the manual specifies this reading be performed by a qualified technician.

3. 03

   Check the supply circuit

   Confirm the unit is on its own dedicated line, as the manual requires, rather than sharing a circuit that may distort voltage.

4. 04

   Compare against the data tag

   Condensing units are designed for plus or minus 10 percent of the data-tag voltage; confirm the supply falls within that range.

5. 05

   Contact service

   The table directs contacting service for this alarm; call 888-994-7636 to address a confirmed over-voltage condition.

When to call a professional

Voltage measurement at the supply must be done by a qualified technician, as both the Danfoss code table and the manual's installation warnings state. Call a qualified electrician or a Randell Authorized Service Agent to verify and correct the line voltage, since over-voltage can damage the compressor and void warranty. Do not attempt live electrical readings yourself; reach service at 888-994-7636.