Rheem Error Code 28: High line voltage (Heat Pump)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rheem error code 28 on a heat pump means: High line voltage. It is also called Rheem diagnostic code 28.

Medium severityHeat PumpRheem/Ruud PRL-JEC heat pump (Comfort Control2 ICC)

Homeowner? What Rheem code 28 means for you

Check, then call Your heat pump is reporting: High line voltage. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rheem error code 28 mean?

The ICC detects line voltage above the allowed range.

Applies to: (-)PRL-JEC 2-stage 16 SEER heat pumps: RPRL/UPRL-024JEC, -036JEC, -048JEC, -060JEC

Common causes of Rheem code 28

Utility supply voltage high
Wrong unit voltage for the supply

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rheem models that use code 28

RPRL-024JEC RPRL-036JEC RPRL-048JEC RPRL-060JEC

Other Rheem Heat Pump codes

Code	Meaning
7 flashes (L terminal)	L-terminal fault output: Open run circuit
8 flashes (L terminal)	L-terminal fault output: Control mis-operation
09	Low secondary (control) voltage
9 flashes (L terminal)	L-terminal fault output: Low control voltage
21	Low pressure control (LPC) open
27	Low line voltage or no line voltage
29	High pressure control (HPC) open
30	ICC fuse open
80	Low airflow
83	Condenser coil temperature sensor fault
84	Outdoor ambient temperature sensor fault
90	Communication fault

All Rheem Heat Pump error codes →

Rheem code 28: homeowner questions

What does Rheem code 28 mean?

High line voltage. The ICC detects line voltage above the allowed range.

Is it safe to keep using my heat pump with code 28?

It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Can I reset Rheem code 28 myself?

You can try one reset (power off for 30 seconds, then on). If Rheem code 28 comes back, the cause is still there and a licensed technician should check it.

Who can fix Rheem code 28 near me?

Aurora Star Tech Inc. repairs Rheem heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

Troubleshooting guides

Heat pump will not defrost / incomplete or excessive defrost Rheem · Heat Pump
Insufficient cooling / pressure problems Rheem · Heat Pump
Outdoor fan runs but compressor does not Rheem · Heat Pump
Outdoor unit will not run Rheem · Heat Pump

Source: Rheem (-)PRL-JEC Heat Pump Installation Instructions, 12.6 ICC Diagnostic Codes, p.30. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.