2P40A120V – CONTACTOR (C240B)

If your AC clicks but doesn’t start, or the outdoor unit won’t turn on at all, the contactor is the first thing to check. This two-pole 40A contactor uses a 120V coil — less common than 24V in residential but used in certain commercial and specialty setups where the control circuit runs on line voltage.

Replaces: C240B, 2P40A120V

Fits: Commercial and specialty AC systems requiring a 2-pole 40A contactor with 120V coil

Need help? See our AC Clicking But Not Starting Guide.

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• Poles2
• Amps40 RLA (full load)
• Coil Voltage120V AC
• TerminalsScrew + push-on quick-connect
• Operating Temp-40°F to 158°F
• UL ListedYes

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• C240B
• CONTACTOR

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• Commercial and packaged equipment using 120V line-voltage coil
• Some larger residential equipment with line-voltage thermostats
• Always verify the existing contactor's coil voltage with a multimeter before swapping — installing a 24V coil where 120V was called for will burn out instantly

How do I know if my contactor is bad?

Pitted or burned contacts, a buzzing sound when the AC tries to start, or the contactor sticking closed (AC runs constantly, never cycles off). Pull the front cover and look at the contacts — if they're black or pitted, replace it.

Can I use a higher amp rating?

Yes. Going up in amps is fine (40A replacing a 30A is safe). Coil voltage MUST match exactly — 24V coil only goes in 24V circuits.

2-pole vs 3-pole — which do I need?

Count the thick wires hitting the line side (top). 2 fat wires = 2-pole (residential split-system). 3 fat wires = 3-pole (3-phase commercial). Most residential is 2-pole.

How long does a contactor last?

5-10 years typical. Insects, dust, and short-cycling shorten the life. If you find ants or wasps nesting in your condenser, that often kills contactors fast.