Carrier WeatherExpert RTU Alarm E17: Supply Fan VFD Fault — Field Diagnosis & Replacement Parts
Published: 2026-06-11
🔍 Symptoms Checklist
- ⚠️ Supply fan stops; unit shuts down to prevent freeze-up
- ⚠️ VFD display shows 'Fault Code 3' or 'Overcurrent'
- ⚠️ More common after power outage or brownout
- ⚠️ Reset works temporarily but alarm returns within 24 hours
🛠️ OEM Replacement Parts
| Part Name | OEM Part Number | Est. Price |
|---|---|---|
| ABB ACH550 VFD Drive (5HP, 460V) | CRR-HK59ZZ003 |
$1,450-1,900 |
| VFD Cooling Fan Assembly | CRR-HK59ZZ021 |
$95 |
| Supply Fan Motor (5HP, 1750 RPM, 460V/3PH) | CRR-MTR05002 |
$680-850 |
📋 Interactive Diagnostic Procedure
Click each step to expand detailed diagnostic instructions. Follow in sequence — each step builds on the previous one.
Frequently Asked Questions
How do I tell if it's the VFD or the motor?
Disconnect the motor leads from the VFD output terminals (U2, V2, W2) and megger the motor independently. If the motor meggers above 20 MΩ and the windings are balanced within 5%, the motor is fine. Reconnect, power up, and run the VFD in HAND mode at 30Hz with no load — if it faults with no motor connected, the VFD is bad. If it runs fine in HAND but faults in AUTO, the problem is the control signal from the main board.
Can I use a generic VFD instead of the Carrier OEM ABB unit?
Technically yes — any 5HP 460V VFD with Modbus RTU can be substituted. But you'll need to program all parameters manually (Carrier's ABB units ship pre-configured with a custom parameter set) and the Modbus register mapping differs from generic ABB defaults. Budget 2-3 hours for parameter entry and communication verification. For emergency replacement, a local ABB distributor can cross-reference CRR-HK59ZZ003 to the standard ABB part number.
🔗 Related Error Codes — Commercial Rooftop Units
Other diagnostic guides in the same equipment category. Common failure patterns often share root causes — cross-referencing speeds up diagnosis.
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⚡ Fault-Induced Energy Waste Estimator
When HVAC equipment runs with active error codes, it operates inefficiently and wastes electricity. Estimate the monthly cost of delaying repairs. All calculations run locally in your browser.
References & Industry Standards
- ASHRAE 15 — Safety Standard for Refrigeration Systems
- ASHRAE 34 — Refrigerant Designation & Safety Classification
- AHRI 550/590 — Water-Chilling & Heat Pump Packages
- SMACNA — HVAC Duct Construction Standards
- Manufacturer Service Manuals — Carrier, Trane, York, Daikin, Lennox