Rivacold HP

What does Rivacold HP mean?

On the Carel controllers fitted to Rivacold plug-in units, HP is the high discharge pressure alarm: when discharge pressure exceeds the configured threshold (HPt), the controller immediately stops the unit and shows HP on the display. Reset is selectable between manual and semi-automatic — semi-automatic clears once the discharge pressure falls back below HPt minus the differential (HPU), but once the maximum number of automatic resets (HPo) is exceeded in the evaluation period, the alarm requires a manual reset.

Symptoms

• Display shows HP and the unit is stopped
• Gauges confirm discharge pressure at or above the trip threshold before shutdown
• Repeated trips end in a latched alarm that no longer auto-clears (manual reset required)
• Condenser noticeably hot, fouled, or its fan not running

Common causes

• Dirty or blocked condenser coil, or obstructed condenser airflow
• Condenser fan failure or wrong rotation
• Ambient too high or hot-air recirculation around the condensing section
• Refrigerant overcharge or non-condensables in the system
• High-pressure threshold/switch set too low for the application

Diagnostic steps

1. 01

   Confirm the trip is real

   Fit gauges and read the actual discharge pressure before resetting. A genuine over-pressure needs a cause found — do not keep resetting a unit that trips again.

2. 02

   Check the condenser first

   Clean a fouled coil, confirm the condenser fan runs and turns the right way, and clear anything blocking airflow or recirculating hot air back into the unit.

3. 03

   Check ambient and installation

   Verify the unit's location is within its rated ambient and has the clearances the installation manual calls for — a boxed-in condensing section will trip HP on hot days.

4. 04

   Reset per the controller's reset mode

   If reset is semi-automatic it clears when pressure falls below the threshold minus the differential; once the maximum number of automatic resets is used up, the alarm must be reset manually.

5. 05

   Suspect the refrigerant side last

   If the condenser, fan, and ambient all check out, the system may be overcharged or holding non-condensables — that is refrigerant-circuit work.

When to call a professional

Anything past condenser cleaning and airflow checks — verifying charge, recovering refrigerant, purging non-condensables, or replacing a high-pressure switch — is sealed-system work for a certified refrigeration technician. Repeated HP trips with a clean condenser mean stop resetting and get the system diagnosed.