Applicable Systems
VRV IV-S
Symptoms
The Daikin outdoor unit displays error E4, indicating low pressure protection activation. The refrigerant suction pressure has dropped below the safe operating threshold.
Possible Causes
- Low pressure switch activated due to insufficient refrigerant
- Refrigerant leak in the system causing low charge
- Expansion valve malfunction not feeding enough refrigerant to the evaporator
- Indoor unit air filter clogged reducing heat load on the evaporator
Troubleshooting Steps
- Step 1: Inspect for refrigerant leaks using an electronic leak detector
Check all flared and brazed joints, Schrader valves, and coil connections - Step 2: Check indoor unit air filters and clean if clogged
Filters must be clean for proper airflow; dirty filters reduce evaporator heat load - Step 3: Verify expansion valve operation and superheat setting
Valve should modulate based on superheat; check bulb strap and insulation - Step 4: Recover and recharge refrigerant to the specified weight
Charge must match the nameplate quantity exactly for proper operation
How to Reset
To reset: 1) Fix any refrigerant leaks and recharge to proper amount. 2) Clean indoor filters. 3) Turn off power for 5 minutes. 4) Restore power. Caution: Low suction pressure can cause evaporator freeze-up and damage the compressor.
Frequently Asked Questions
- Q: What pressure triggers E4 on Daikin units?
E4 triggers when the low pressure switch activates, typically around 0.07 MPa (0.7 bar) for R-410A systems. The exact threshold varies by model - check the service manual.
- Q: Can low refrigerant cause compressor damage?
Yes. Low refrigerant charge reduces cooling of the compressor motor, leading to overheating and potential burnout. E4 must be addressed promptly to prevent compressor damage.
Source: Daikin Air Conditioner Fault Code Reference, Daikin China Official Website Service Section, Code E4
Category: HVAC Residential