How to Decode Tecumseh Compressor Model Numbers: A 6-Step Checklist

If you're replacing a Tecumseh compressor and you're not 100% sure the model number you wrote down is correct, this checklist is for you. It's the same verification process I use at the warehouse before any compressor shipment goes out to a customer.

I'm a quality compliance manager at an HVAC/R parts distributor. I review every compressor unit that crosses our dock—roughly 3,000 a year. Over four years of doing this, I've rejected about 4% of first deliveries for spec mismatches. The common denominator in nearly every case? Someone skipped one of the steps below.

This isn't complicated. It's six checks. Five minutes of verification beats five days of returns, restocking, and angry phone calls.

Step 1: Locate and photograph the data plate

The model number is stamped on a metal plate on the compressor body. Sounds obvious, but you'd be surprised how often people try to read it in place under bad lighting and write down the wrong characters. I've seen "AK9440" read as "AX9440" because of glare. That one letter difference changes the entire component spec—which is somewhat alarming when you consider how easy it is to misread.

Take a photograph with your phone. If the plate is dirty or paint has splattered over it, wipe it clean first. If the stamping is worn, shine a light at an angle—the shadows make the characters readable. And if the compressor faces backward in a condensing unit, don't guess. Unmount it or use a mirror. Guessing is how $400 mistakes happen.

Step 2: Identify the series prefix

Tecumseh compressor model numbers start with letters that identify the compressor family. This is your first filter. The prefix tells you generally what application the compressor was built for—not the exact spec, but the design intent.

• AE: hermetic refrigeration compressors, common in reach-in coolers, freezers, and beverage dispensers.
• AK: medium-temperature refrigeration and air conditioning.
• AW: air conditioning, including heat pump applications.
• AG / AN: larger refrigeration compressors, often found in walk-ins and commercial equipment.

If you're cross-referencing a model that starts with AE and the replacement starts with AK, stop. They may share similar capacity ranges, but the application design assumptions are different. Doesn't mean it can't work—it means you need to verify before you commit, not after.

Step 3: Decode the capacity digits

The numbers after the prefix represent the compressor's nominal capacity, typically in BTU/h divided by 100 or 1000 depending on the series and era. A Tecumseh 3-ton compressor, for example, will usually show capacity digits around 36—representing roughly 36,000 BTU/h. You might see something like AE36xxx or AK36xxx, depending on the generation of the model.

I want to be careful here because the exact mapping has changed across product generations, and there are exceptions. A compressor from the 1980s may follow a different naming pattern than a current model. The data plate lists the BTU/h rating directly on most units—use that as your source of truth, not just the model number math.

Step 4: Check the electrical code

After the capacity digits, there's usually a letter that codes for electrical characteristics: voltage, phase, frequency. This is where I see the most cross-reference errors in our industry.

Here's a typical scenario: a technician looks at a model with an "E" suffix and assumes it's a 208-230V single-phase unit because that's "what E means." But the electrical code is only meaningful within the context of the specific series. A 460V three-phase unit and a 230V single-phase unit look nearly identical from the outside. Different wiring. Different start components. Install the wrong one and you'll either trip protection immediately or burn out the motor winding within hours.

The letter on the plate isn't a universal code—it's a position in the model sequence that maps to a spec table. Look it up, don't guess.

Step 5: Verify the application suffix

The characters after the dash—usually two or three—identify the specific build: refrigerant type, oil type, start components, sometimes even the factory of origin. Two compressors with identical prefixes and capacity digits can have different suffixes for a real reason. One might be R404A with POE oil. The other might be R134a with mineral oil. Put the wrong one in a system, and you'll get compressor failure, contaminated refrigerant, or both.

The suffix is not a revision number. It's a specification. Since I implemented our plate-check protocol in 2022, I've caught seven wrong-spec units that would have gone out the door—and every single one was caught by checking the suffix against the Tecumseh spec sheet. It takes thirty seconds.

Step 6: Cross-reference against the actual application

Here's the step most people skip: a cleanly decoded model number doesn't mean the compressor is right for your application.

Take a Tecumseh 3-ton compressor used in a heat pump dryer versus one in a residential air conditioning unit. The capacity might be similar, but the heat pump dryer compressor is designed for a different operating envelope—higher pressure ratios, different suction conditions, different start behavior. The OEM spec for that dryer is specific to that unit. If you order a replacement that decodes correctly on paper but doesn't match the OEM application, it may fail within the first season. At least, that's what I've seen in our return data.

Same thing with air compressors. Some DeWalt air compressor models have used Tecumseh pumps over the years. If you're servicing a DeWalt unit, the pump might resemble a refrigeration compressor, but it's not—it's an air compressor pump optimized for intermittent duty and no refrigerant return. Don't cross-reference between them. Different application, different design.

I'll be honest about how I handle cross-references. I went back and forth for a while on whether to approve aftermarket brands when we first started sourcing alternatives to OEM parts. The OEM model is verified by the manufacturer's own documentation—simple. Aftermarket cross-references require more trust. What settled it for me was a simple rule: I only approve an aftermarket replacement when the manufacturer publishes an explicit cross-reference sheet. If they won't put the compatibility in writing, the risk is on us.

Common Mistakes I See

Recurring problems that cause most returned Tecumseh compressors:

• Misreading the plate. Corrosion, glare, grease. Photograph it and zoom in.
• Ignoring the suffix. The electrical and application codes are the number one source of spec mismatches in aftermarket orders.
• Trusting box labels. In Q1 2024, we received a pallet of 200 compressors where the vendor's box label said one electrical code and the unit plate said another. The whole batch went back. That was a $16,000 redo, and the vendor covered it—but our customer still had to wait.
• Assuming "cross-reference" means "identical." To be fair, many aftermarket compressors perform fine. But "fine" is not the same as "drop-in identical." Verify start components, oil type, and mount configuration before committing.

Questions We Get at the Parts Counter

What's the difference between a boiler vs water heater?

This comes up more often than you'd expect, usually from customers planning an equipment upgrade and getting tangled in terminology. A water heater heats potable water and stores it—or heats it on demand. A boiler produces hot water or steam for space heating through radiators or radiant floor loops. A combi boiler can do both space heating and domestic hot water, but that's a specific type. The question isn't "which is better"; it's "what are you trying to heat?" They're different machines for different jobs. Same logic applies to compressor selection: match the unit to the application, not the other way around.

Can I use a heat pump dryer compressor for refrigeration?

No. A heat pump dryer compressor is optimized for the dryer's closed-loop operation. It may look like a refrigeration compressor, but the operating conditions are different. Use the OEM-specified compressor.

Do all DeWalt air compressors use Tecumseh pumps?

No. DeWalt has used multiple pump suppliers over the years. Check the actual pump manufacturer and model stamped on the unit.

The Takeaway

Photograph the plate. Decode the prefix. Check the capacity digits. Verify the electrical code. Confirm the suffix. Cross-reference the full model against the actual application. Six steps, five minutes, zero surprises.

I'll take that over another $16,000 pallet return any day.