KCHV Outdoor Unit - E1 High Pressure Protection on KSHV / WSHV / KDHV / KBHV Indoor Units (R32 Systems)
Compressor High‑Pressure Protection (E1)
Applies to: KCHV Outdoor Units used with KSHV, WSHV, KDHV, KBHV indoor units (R32 inverter systems).
When the outdoor unit detects high refrigerant pressure, the High‑Pressure (HP) Switch opens and signals the PCB to stop the compressor. The system then displays E1 on the controller and outdoor diagnostic LEDs.
E1 high pressure fault on KCHV outdoor units with KSHV, WSHV, KDHV, KBHV indoors. Covers causes, diagnosis steps, HP switch, fan and refrigerant checks.
What the E1 Fault Means
The system is overheating on the refrigerant side.
Think of it as:
“Pressure is too high — compressor stopped to avoid damage.”
High pressure usually means:
- Poor heat rejection
- Airflow problems
- Refrigerant flow restriction
- Overcharge or non‑condensables
- Faulty HP switch or wiring
Common Causes
High‑Pressure Switch Issues
- Loose or corroded plug
- Damaged wiring to PCB
- Faulty HP switch
Airflow / Fan Problems
- Outdoor fan not running or slow
- Dirty condenser coil
- Blocked air discharge (walls, enclosures)
System Refrigerant Pressure Issues
- Overcharged system
- Liquid line restriction
- EXV stuck or malfunctioning
- Air / non‑condensables in system
Troubleshooting (Step‑by‑Step)
Step 1 – Inspect HP Switch
- Check plug for tightness
- Check for bent/corroded pins
- Inspect cable continuity
- Replace switch if it trips at normal pressure
Step 2 – Check Outdoor Fan Operation
- Confirm fan starts & runs at full speed
- Check for seized bearings or obstructions
- Ensure correct rotation
Step 3 – Assess Coil and Airflow
- Clean condenser coil
- Ensure clearances around unit
- Remove blockages
Step 4 – Check System Pressures & Charge
- Confirm correct refrigerant charge
- Identify high head pressure
- Check for restrictions (filter drier, EXV, kinks)
Step 5 – Inspect Refrigerant Piping
- Look for crushed/kinked sections
- Verify pipe sizing and lengths
Step 6 – Reset & Test
After repairs:
- Restore power
- Clear E1
- Run the system in cooling and monitor pressures
When to Replace Parts
Replace the HP switch when:
- Opens prematurely
- Does not reset at normal pressures
- Wiring and plugs are verified good
Replace Outdoor PCB when:
- HP switch OK
- Fan OK
- System pressures normal
- Still repeatedly logs E1 without cause
Technician Quick‑Reference
(For qualified refrigeration mechanics — fast diagnosis table)
E1 Fault – 30‑Second Tech Summary
| Symptom | Likely Cause | Quick Test | Action |
|---|---|---|---|
| E1 appears immediately on startup | Open HP switch / wiring fault | Check continuity across HP switch | Replace switch or repair wiring |
| E1 after a few minutes cooling | High head pressure | Check fan speed, coil cleanliness | Repair fan / clean coil / fix airflow |
| E1 in hot weather only | Marginal heat rejection | Check clearances & discharge air recirculation | Improve airflow, relocate obstacles |
| E1 after service work | Overcharge or air in system | Check running pressures | Correct charge / re‑evacuate |
| E1 with normal pressures | Faulty HP switch or PCB | Jump‑test switch for diagnosis only | Replace switch or PCB as required |
Rapid Diagnostic Checklist
- ✔ HP switch plugged in firmly & pins straight
- ✔ Outdoor fan running at correct RPM
- ✔ Condenser coil clean & no airflow blockage
- ✔ Refrigerant charge correct
- ✔ No liquid line restrictions
- ✔ EXV opening/stepping correctly
- ✔ Piping not kinked or undersized
Summary
E1 = High Refrigerant Pressure = Compressor Protection.
Fix airflow → check HP switch → check charge → check EXV → check restrictions.