How to Replace SPP5 Hard Start Kit on Trane Carrier Lennox Goodman Rheem AC Units — Step-by-Step

Your AC compressor's struggling to start. You hear that labored humming sound for 2-3 seconds before it finally kicks in, or worse — the unit trips your breaker every time it tries to fire up. This is the classic sign that your hard start capacitor has failed. The SPP5 hard start kit (also sold as TJSPP5 or HS520) is the universal replacement that'll get your Trane, Carrier, Lennox, Goodman, or Rheem system starting smoothly again.

What You Need Before Starting

• Needle-nose pliers
• Wire strippers
• Flathead screwdriver
• Voltage tester (non-contact type recommended)
• Electrical tape
• Drill with 1/4" bit (if mounting bracket holes don't line up)

Repair Time: 15-25 minutes

Difficulty: Moderate — Requires working with live electrical connections

Safety First

Turn off power at the breaker AND the disconnect box at your outdoor unit. Even with power off, capacitors store electrical charge that can shock you. Use a screwdriver with an insulated handle to short the capacitor terminals together before touching any wires. If you've never worked with capacitors before, call a tech — these components can seriously hurt you.

Step 1: Access the Electrical Compartment

Remove the service panel on your outdoor unit — usually held by 4-6 screws or quarter-turn fasteners. The hard start kit mounts directly to the compressor's run capacitor or near the compressor itself. Look for a small silver or black cylindrical component about 2 inches tall with two or three wire leads coming out.

Step 2: Photograph and Disconnect the Old Hard Start Kit

Take a clear photo of the existing wire connections with your phone — this is your wiring diagram. The SPP5 connects between the compressor's start terminal and common terminal. Typically you'll see one wire going to the capacitor's HERM terminal and another to the common (C) terminal. Use needle-nose pliers to carefully pull off the spade connectors. If they're crimped or soldered on, cut the wires about 3 inches from the old kit.

Step 3: Mount the New SPP5 Kit

The SPP5 comes with a metal mounting bracket. Position it near the compressor or adjacent to the capacitor where you removed the old one. If mounting holes don't align with existing holes, drill new 1/4" mounting holes in the unit's frame. Don't drill into refrigerant lines or electrical conduit. Secure with the provided screws.

Step 4: Connect the Wire Leads

Match the wire colors from your photo. The SPP5 has two leads — one connects to the compressor start circuit (usually the HERM terminal on the capacitor) and the other to common. If you cut the old wires, strip 1/4" of insulation from the ends and use the provided crimp connectors or wire nuts. Push spade connectors firmly onto the capacitor terminals until they click. Wrap any exposed connections with electrical tape.

Step 5: Secure Wiring and Close Up

Use a zip tie or the included wire clip to secure the new hard start kit's wires away from the compressor and fan blade. Make sure nothing can vibrate loose or get caught in moving parts. Double-check all connections are tight. Replace the service panel.

Testing After Installation

Turn power back on at the disconnect, then at the breaker. Set your thermostat 3-4 degrees below room temperature to call for cooling. Listen at the outdoor unit — the compressor should start within 1-2 seconds with no labored humming or clicking. If you hear repeated clicking or the unit won't start, turn power off immediately and recheck your connections. A properly installed hard start kit makes the compressor sound smoother and more confident when starting.

Frequently Asked Questions

Will the SPP5 work on my specific model if it's not listed?

The SPP5 is a universal hard start kit compatible with most residential AC compressors from 1 to 5 tons. It works on Trane 4TTB6061A, Carrier 38CKC036300, Lennox Y8806, Goodman GSX130361, Rheem RA1436AJ1NA, and hundreds of other models. Check your compressor nameplate — if it's a single-phase compressor running on 208-240V, the SPP5 will work.

How do I know if I need a hard start kit or just a regular run capacitor?

If your compressor starts but the fan runs weak or not at all, that's usually the run capacitor. If the compressor hums, struggles, or trips the breaker when trying to start, that's the hard start kit. When in doubt, replace both — a failed run capacitor often stresses the hard start kit and vice versa.

Can I install this without discharging the refrigerant?

Yes. The hard start kit mounts entirely on the electrical side of the system. You're not touching any refrigerant lines, valves, or sealed components. This is a purely electrical replacement that doesn't require EPA certification or refrigerant handling.