CXM vs. DXM vs. VHS: How to Identify Your 816 Series Control Board Before You Order a Replacement Chassis

When you're replacing a vertical-stack water source heat pump chassis, matching the BTU size and voltage is the easy part. The part that trips people up is the control board — because the model number on your existing unit's data plate almost never matches the model number on the replacement chassis we stock, even when it's a straight cross-reference. A ClimateMaster model number, a California Heat Pump model number, and a ColdPoint/Adirondack-Aire 816 Series model number can all describe functionally the same chassis and still look nothing alike.

We ran into this directly on a recent quote: a customer's paperwork listed ClimateMaster model numbers, and we needed to confirm whether our in-stock 816 Series chassis would actually work as a drop-in. So we went straight to the source and asked Cold Point's factory team. Their answer is worth putting in writing, because it applies to more than just that one job.

The short answer from Cold Point's factory

Per Cold Point Corporation: 816 Series chassis are built with one of two control schemes, and the model number alone doesn't always tell you which one you have. The two schemes are:

• CXM/DXM controls — 2 wiring harnesses, terminating in a 9-position connector and a 2-position connector.
• VHS/CXM controls — 3 wiring harnesses, terminating in a 9-position connector, a 2-position connector, and a 6-position connector.

Every 816 Series chassis we stock is built with CXM/DXM controls. If the control scheme on the unit you're replacing can't be confirmed ahead of time, Cold Point's recommendation is to order the CXM/DXM chassis we have on the shelf and add the optional 816 CXM/DXM to VHS Conversion Harness Kit (part 80363) — that combination works with either control scheme, so you're not stuck guessing before the unit ships.

CXM, DXM, and VHS — what these letters actually mean

None of this is marketing language — these are ClimateMaster's own control platform names, and Cold Point builds the 816 Series chassis to be compatible with them. In plain terms:

• CXM is ClimateMaster's base digital heat pump controller — a microprocessor board that watches refrigerant pressures and coil temperatures and shuts the compressor down safely instead of letting a fault damage the unit. It's the standard "smart" control found on most mid-2000s-and-newer water source heat pumps.
• DXM is the deluxe version of the same control family — same safety monitoring as CXM, with added features (multiple status LEDs, more jumper/DIP-switch configuration options, support for two-stage compressors). CXM and DXM boards wire into the chassis harness the same way, which is why they're treated as one control scheme rather than two.
• VHS refers to the older-generation control scheme used on some 816-cabinet vertical stack units. It predates the CXM/DXM platform and uses an additional wiring harness that CXM/DXM-only units don't have.

The practical difference that matters when you're ordering a replacement isn't how the board works internally — it's how many harnesses plug into it and how many pins each one has.

How to tell which control scheme your unit has

You don't need to be an electrician to check this — you just need to see the connectors. Here's the field check:

1. Shut off power at the disconnect before opening any control panel.
2. Open the control access panel and locate the control board — it's the circuit board the unit's internal wiring harness plugs into (not the screw-terminal strip where the field thermostat wires land).
3. Count the harness connectors plugging into the board:
   • Two connectors — one 9-position, one 2-position — means CXM/DXM controls.
   • Three connectors — a 9-position, a 2-position, and a 6-position — means VHS/CXM controls.

If you're not comfortable opening an electrical panel yourself, that's a job for a licensed technician — or send us a photo of the data plate and, if you can safely get one, a photo of the control board and harness connectors. We can help identify what you're working with before you order.

What this means when you're ordering a replacement 816 Series chassis

Don't try to match the replacement to your old unit's model number character-for-character — across manufacturers, that's not how the numbering works. What actually needs to match is capacity (BTU), voltage, and control scheme. Cold Point's Adirondack-Aire 816 Series is a documented cross-reference for ClimateMaster 816 and California Heat Pump CHP-RF chassis, and every one we stock ships with CXM/DXM controls.

816 Series Chassis We Stock (CXM/DXM Controls)

• 10k — 208V, 265V
• 12k — 208V, 265V
• 15k — 208V, 265V
• 20k — 208V, 265V
• 30k — 208V, 265V
• 36k — 208V, 265V

Can't confirm the control scheme? Add the conversion harness.

If you can't verify the control scheme before the unit ships — the old chassis is inaccessible, the customer can't get you a photo, or the job just needs to move — order the CXM/DXM chassis above and add the 816 CXM/DXM to VHS Conversion Harness Kit (part 80363). It's the factory-recommended way to cover both control schemes without special-ordering a chassis and waiting to find out you guessed wrong.

Not sure what you're working with?

Send us the model number and voltage you have, along with a photo of the data plate and the control board if you can get one safely. We'll help you cross-reference it and make sure the chassis and control scheme are right before anything ships.

Frequently Asked Questions

What's the difference between CXM and DXM controls?

CXM is ClimateMaster's base digital heat pump controller — a microprocessor board that monitors refrigerant pressures and coil temperatures and shuts the unit down safely on a fault. DXM is the deluxe version of the same platform, with added status LEDs and configuration options. Both wire into the chassis the same way, which is why they're grouped together as one control scheme.

What is VHS control on an 816 Series water source heat pump?

VHS refers to an older-generation control scheme used on some 816-cabinet vertical stack units, predating the CXM/DXM platform. It uses an additional wiring harness (a 6-position connector) that CXM/DXM-only units don't have.

How do I know if my unit has CXM/DXM or VHS/CXM controls?

With power shut off at the disconnect, open the control panel and count the harness connectors plugging into the control board. Two connectors (9-position and 2-position) means CXM/DXM controls. Three connectors (9-position, 2-position, and 6-position) means VHS/CXM controls.

Will a ColdPoint 816 Series chassis work as a replacement for my ClimateMaster unit?

ColdPoint's Adirondack-Aire 816 Series is a documented cross-reference for ClimateMaster 816 and California Heat Pump CHP-RF chassis. Match capacity, voltage, and control scheme rather than the exact model number, which won't match across manufacturers.

What is the 816 CXM/DXM to VHS Conversion Harness Kit (part 80363) for?

It adapts a CXM/DXM-controlled 816 Series chassis so it can also accept a VHS/CXM wiring configuration. Cold Point recommends it specifically for cases where the control scheme of the unit being replaced can't be confirmed before ordering.

Do I need the conversion harness if I already know my control type?

No. If you've confirmed your existing unit uses CXM/DXM controls, our in-stock 816 Series chassis will match without any additional parts. The harness kit is only needed to also support a VHS/CXM wiring configuration.