AC Contactor Cross-Reference Chart

Definite purpose contactors are one of the easiest HVAC parts to cross — and one of the easiest to get wrong, because two of the numbers printed on the side mean completely different things. Below: 112 factory contactor numbers with the rating each manufacturer publishes for them, 21 White-Rodgers published crosses, and 241 rows of Supco, MARS and Packard interchange — plus the selection rules that actually matter.

What has to match

One pole, two pole, three pole

Pole count is the first thing to get right and the easiest to see. These are photographs of stock on our own shelf — tap any of them for the full specification.

One pole1P40A24VOne set of contacts. What the trade calls a 1-pole is really 1.5 pole with a shunt — both legs land on it, one switched and one not.Two poles2P40A24VBoth legs switched. Shares the same footprint as most 1-pole units, so it is a safe upgrade. The reverse is not true.Three poles3P40A24VThree-phase or multi-circuit work. Different body, different mounting — not a swap for either of the above.

Coil voltage is a separate question entirely — we stock each of these in 24V, 120V and 240V coils, and they look identical from the outside. Read the coil rating before you match anything.

Why your “1-pole” has two legs on it

This confuses people at the counter every week, and it is not their fault.

What everybody calls a 1-pole HVAC contactor is actually a 1½-pole, or “1-pole with shunt.” It has one switched pole plus a permanently jumpered bar for the other leg. Both L1 and L2 land on it — one gets switched, one does not. That is why it drops straight into a 2-pole footprint and why the wiring looks the same at a glance.

Different brands print it differently for the same part: MARS says “1 Pole with Shunt,” Supco says “1.5 Pole,” Jard says “1-1/2 Pole,” Totaline says “Single Pole with Shunt.”

Can a 2-pole replace a 1-pole?

Yes, and it is the better part. It does strictly more — it opens both legs instead of one — it fits the same holes in the 30–40 A sizes, and it costs a few dollars more. The only difference is where the wires land: on the 1½-pole both legs go to the same side with one on the shunt bar; on a 2-pole you land one leg per pole.

The reverse is not an equivalent. Do not put a 1½-pole where a 2-pole was unless you know the equipment was designed for it.

Copeland goes further and recommends against the unswitched-leg approach for reliability as well as safety — they note evidence that unexplained spring-startup compressor failures traced back to winter lightning finding a path through the unbroken line. Two-pole contactors are cheap insurance against that.

FLA vs resistive amps — the number people get wrong

Look at the side of a contactor and you will usually see two current ratings, something like 30 FLA / 40 Res. They are not two ways of saying the same thing.

Published rating families run like this. Note that LRA falls as voltage rises — a definite purpose contactor holds roughly 6× its FLA at 230 V, 5× at 460 V and 4× at 575 V, which is one of the real differences between a DP contactor and a general purpose one.

Two of those resistive figures are published differently by different manufacturers — MARS lists 63 at 50 FLA where Square D and Titan Max list 65, and Titan Max lists 90 at 75 FLA where the others list 94. Use whatever the brand in your hand publishes.

Picking the right amp rating

The manufacturer method is nameplate-based, not tonnage-based: take the compressor’s rated load amps off the data plate, add the condenser fan motor amps, pick the next amp rating above that total, then check that the contactor’s locked-rotor rating clears the compressor’s LRA.

You will find tonnage charts all over the internet — roughly 30 A for 2½ to 3 ton, 40 A for 3½ to 4 ton, 40 to 50 A for 5 ton. No manufacturer publishes one. They are a reasonable starting point for what to pull off the shelf and nothing more. Confirm against the data plate before you buy.

Is going bigger harmful? No manufacturer document says a larger contactor damages anything. The limits on oversizing are physical rather than electrical — above 40 A the body gets bigger, the mounting changes and the lugs change. Match or exceed; one size up is fine if it fits and your wire lands.

Decoding the part number on your old contactor

Most of these tell you the spec if you know how to read them.

Lennox is the exception — their contactor numbers are short opaque codes with no consistent prefix, so there is nothing to decode. Bring the part.

Goodman and Amana: the part number is the spec

Goodman contactor numbers read straight out. CONT2P030024VS is a 2-pole, 30 amp, 24 volt coil contactor, and you never have to look it up. We checked this against every Goodman contactor description in our data and it holds on all of them, with no exceptions.

Rheem and Ruud: the XMC0 code on the box

Rheem’s own part numbers (42-109499-xx) tell you nothing — the suffix is just a sequence. But the contactor inside carries an XMC0- code, and that one does decode: the first two digits are the amp rating, the last digit is the pole count.

A trailing letter (XMC0-323A) marks an auxiliary-contact variant. The 60 amp part is coded 633 because 63 A is the IEC frame size it is built on; Rheem still sells and labels it as a 60 amp contactor.

D158999P02, D157567P02 and the other “D” numbers

This is the number people bring us most often out of a Trane or American Standard condenser, and it is the one that causes the most trouble — because it is not the equipment maker’s part number at all. It is the contactor manufacturer’s number, stamped on the part by the company that built it. You will see the same numbers sold under the Hartland Controls name and under “Homer.”

Here is the problem with buying off that number. Hartland Controls’ own published catalog lists its contactors by a completely different code — poles, coil voltage and amps spelled out — and contains no index of the D-numbers at all. So there is no manufacturer document that will tell you what rating a given D-number is. What fills that vacuum is resale listings, and they contradict each other: we found the same D-number advertised as a 30 amp part on one site and a 40 amp part on another, and one seller had a 1-pole and a 2-pole description attached to the same number on the same page.

What to do instead. Don’t order by the D-number. Turn the contactor over and read the label — it states the pole count, the FLA rating and the coil voltage, and those three numbers are the whole decision. Take them to the what has to match section above, or bring the part in and we will put it next to what’s on the shelf.

Factory contactor numbers — what the number actually means 112 factory part numbers

Every number below is an equipment manufacturer’s own contactor part number, with the rating the factory publishes for it. This is the table for the person who pulled the contactor out, read the number off the side, and wants to know what it is before they go looking for one.

What this table is and isn’t. It is a rating lookup, not a cross-reference. We are not telling you “part X replaces part Y” unless a manufacturer published that cross — see the White-Rodgers table below for the ones that are published. What this table gives you is the three numbers that actually decide interchange: pole count, compressor FLA, and coil voltage. Match those three off the what has to match rules and any definite-purpose contactor of that size will run the unit.

Swipe the table sideways on a phone.

Where a cell says not stated, the factory doesn’t publish that figure for that part number, and we’d rather leave it blank than fill it in with what it probably is. Nearly every residential condenser contactor runs a 24 volt coil — but “nearly every” is not a spec, and a rooftop or a commercial unit is exactly where that assumption bites. Where a second number appears after the FLA rating, that is the resistive rating — see FLA vs resistive amps for which one you match on.

White-Rodgers published cross — Carrier and ICP 21 factory numbers

These are not our opinion. White-Rodgers publishes a replacement-parts guide for Carrier and ICP branded equipment, and every factory number in the left column is listed there against the same universal contactor. If your number is in this list, the cross is the manufacturer’s, not ours.

Swipe the table sideways on a phone.

Source: White-Rodgers / Copeland R-4838-1, Replacement Parts for Carrier and ICP Branded Equipment, rev. 2/22. If a number of yours is not on this list, that does not mean nothing fits it — it means White-Rodgers has not published a cross for it, and we are not going to invent one on a web page.

Brand interchange grid 39 Supco parts × 19 brands

From Supco’s published cross-reference. Find any number in any column and read across for the equivalent in every other brand.

Swipe the table sideways to see all brands →

MARS ↔ Furnas / Siemens with full specs 112 rows

From the MARS 780 catalog. Every row carries the poles, both amp ratings, locked rotor, coil voltage and terminal type — so you can confirm the match rather than trust it.

Swipe the table sideways to see all columns →

Titan Max ↔ MARS ↔ Furnas 90 rows

Packard’s Titan Max line, now under DiversiTech. Note that Packard, DiversiTech and Titan Max are one family rather than three independent brands.

Swipe the table sideways to see all columns →

Ants: the Dallas failure mode

If you have pulled a contactor apart in North Texas and found it packed with dead ants, you are not imagining a local problem.

The tawny crazy ant is established across Texas, Louisiana, Mississippi and Florida. They are under an eighth of an inch and they get into contactor housings. Texas A&M AgriLife describes the mechanism: an ant gets shocked crossing the contacts, releases an alarm pheromone that calls in more ants, and those get electrocuted too. The carcasses build up between the contacts and physically stop them closing. Fire ants do the same thing.

An open-frame contactor has nothing to keep them out. If this has happened to you once at a given address, it will happen again — and a sealed or enclosed contactor is the part to ask for. Manufacturers are blunt that half-measures do not work: arc covers, dust covers and plastic noise shields reduce the problem but ants still get in.

Worth knowing before you buy the same open contactor a third time.

Testing a contactor

Contactor, capacitor, or something else?

The clean way to think about it: a contactor is a switch. If it is passing full line voltage downstream and the compressor still will not run, the contactor did its job. Look at the capacitor.

Looking for CNT09648 or CNT05482?

This trips people up constantly because CNT and CTR look alike on a parts list. If the number on your part starts CNT, you are holding a board, and a contactor cross-reference will not help you.

Frequently Asked Questions

Sources: Supco definite purpose contactor cross-reference (F155-040417); MARS 780 catalogue; Packard Titan Max cross-reference; Square D 8910 catalogue; Copeland application engineering bulletin AE10-1244 on contactor selection; White-Rodgers SureSwitch literature; Texas A&M AgriLife and ACHR News on tawny crazy ants. Manufacturers publish these as functional equivalents rather than exact matches — verify poles, coil voltage, amp rating and terminal type before installing. Compiled July 2026.

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