Hard Start Kit 3.5-5 Ton — Universal HVAC Compressor Saver
Order before 3PM CST — ships same day.
Standard delivery 2-5 business days. Express options at checkout.
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Universal hard start kit for 3.5-5-ton AC compressors. CSR-U2 style, fits larger residential and light commercial 3.5-5 tons. A hard start kit reduces compressor startup time by up to 50%, dramatically lowering electrical stress and extending compressor life — especially critical in hot climates like Houston where compressors cycle frequently.
When you need one: Compressor struggles to start (slow or delayed startup), lights dim when AC kicks on, breaker trips on startup, compressor hums but won't start on hot days, or your system is over 5 years old and you want to extend its life.
- Tonnage: 3.5-5 ton systems
- Type: Potential relay with start capacitor
- Voltage: 115V-288VAC (universal)
- Installation: Pre-wired, connects directly to compressor terminals
- Benefit: Reduces startup amps by 50%, extends compressor life
- Warranty: 1-year replacement warranty
Install difficulty: 1/5 — Easiest HVAC repair. Turn off power. Connect 2 wires to compressor terminals (usually between HERM and COMMON). Secure with zip tie. 5-10 minutes. No tools needed beyond a screwdriver.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days