Tool lists online tend to be written by people selling tools. This one is sorted by what you'll actually do. Buy the first group now. Get the others when a project calls for them.
Everyday maintenance
- Nut drivers, 1/4" and 5/16": almost every service panel on furnaces and condensers uses these screw sizes.
- Wet/dry shop vac: for condensate lines, drain pans and cleaning around the outdoor unit.
- Fin comb: straightens bent coil fins so air can pass through.
- Coil cleaner: a foaming no-rinse type for indoor coils, and an outdoor condenser cleaner.
- Headlamp: furnace closets and attics are always dark.
Electrical troubleshooting
- Non-contact voltage tester: a quick first check that something is live. Don't rely on it alone to confirm power is off.
- Multimeter with capacitance and a clamp: for checking voltage, testing capacitors and measuring motor current. A true-RMS meter is worth the small extra cost.
- Insulated screwdrivers: for anything near the contactor or capacitor.
Installing a mini split
This is where the cost jumps, so borrow or rent what you can.
- Torque wrench with flare crowfoot adapters: flare nuts need specific torque values.
- Vacuum pump and micron gauge: see the vacuum guide. The micron gauge matters more than the pump brand.
- Flaring tool: only if you're cutting and flaring line sets yourself. An eccentric cone flaring tool makes consistent flares.
- Hole saw for the wall penetration: check the manual for the required size, commonly around 2.5 to 3 inches.
- Level and stud finder: the indoor unit's mounting plate needs to be level and anchored well.
What you can skip
Unless you hold an EPA 608 certification, a manifold gauge set is mostly a pressure-testing and vacuum tool for you, not a charging tool. Buying and adding refrigerant to most systems is regulated in the US. If a system needs refrigerant, it also has a leak, and that needs a technician.