3P40A240V – CONTACTOR (3 POLE, 40 RLA, 240V COIL)
When you swap a contactor, also pull the capacitor and bring both in — pitted contactor contacts almost always mean the cap was weak and the compressor was straining to start. We'll test the cap free, and if it's marginal you'll save yourself a second trip.
10226 Plano Rd, Suite 104, Dallas TX 75238
Questions? Call or text (214) 340-9421
Mon–Fri 10 am – 7 pm | Sat 10 am – 3 pm
Symptoms of failure
- AC will not start and you hear a buzz or chatter at the contactor
- Contacts look pitted, blackened, or welded together
- Unit runs constantly and will not shut off when the thermostat is satisfied
- Loud chattering from the outdoor unit that comes and goes
- Ants or debris packed around the contacts
- Thermostat calls for cool and nothing happens outside
Seeing these does not always mean this part is the culprit. Bring the old one in and we will meter it at the counter, free, before you buy.
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 3-pole 40A contactor with a 240V coil is used in 3-phase commercial HVAC systems. Silver cadmium oxide contacts for long life and reliable switching.
Replaces: C340C, DP402403, 3P40A240V
Fits: Commercial HVAC and refrigeration systems requiring a 3-pole 40A contactor with 240V 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
- Poles3
- Amps40 RLA (full load)
- Coil Voltage240V AC
- TerminalsScrew + push-on quick-connect
- Operating Temp-40°F to 158°F
- UL ListedYes
Installing it yourself
- Kill power at the disconnect and confirm 0V.
- Photograph the wiring first. Line, load and the 24V coil all land in specific places.
- Move one wire at a time from old to new so you cannot cross them.
- Match pole count, coil voltage (usually 24V) and FLA rating. FLA is the number that matches a compressor, not the resistive rating.
- A 2-pole is a safe upgrade over a 1-pole with shunt. Going the other way is not.
- Mount, land the wires, restore power.
- If it chatters again with a new contactor, the problem is low control voltage, not the contactor.
Power off at the disconnect first, every time. Not sure partway through? Bring it to the counter and we will walk it with you.
Cross-reference numbers
This part replaces the following OEM and aftermarket numbers:
- 3P40A240V
- DP402403
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 240V 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 240V 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.
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