The Milwaukee 2236-20NST Clamp Meter for HVAC/R (NIST) is a professional clamp meter for heating, ventilation, air conditioning, and refrigeration service work. This is a clamp meter designed for HVAC/R electrical testing and troubleshooting. Model Number 2236-20NST. It is aimed at technicians working in residential, commercial, and industrial settings who need dependable current, voltage, temperature, and continuity checks in one handheld tester.

On the electrical side, this meter measures up to 600 amps AC and up to 600 volts AC/DC, with True RMS capability for more reliable readings across a wider range of real operating conditions. It also reads 600 microamps DC for flame rectification work, which makes it especially relevant for furnace and burner diagnostics. That combination is what separates an HVAC-focused clamp meter from a basic electrical tester.

The jaw design is a big part of the story here. Milwaukee gives you a 1.3 inch jaw opening plus a thin jaw profile, so the meter can reach into panels, around large conductors, and through wire bundles without turning a simple reading into a wrestling match. For service techs working inside rooftop units, air handlers, condensers, or packed control cabinets, that access matters just as much as the raw measurement range.

Milwaukee also built this meter around actual field use instead of bench-top convenience. The high-contrast white-on-black display with backlight is easier to read in dark mechanical rooms and low-light service conditions. A built-in LED work light helps when panel lighting is poor, and non-contact voltage detection gives you a quick way to verify the presence of voltage before you move further into diagnosis. Rugged over-molding adds grip and helps the tool stand up to daily truck, bag, and panel work.

For temperature-related service checks, the included dual banana thermocouple input lets you take contact temperature readings from -40 degrees Fahrenheit to 752 degrees Fahrenheit. That makes this a more useful all-around service meter for refrigeration and HVAC equipment where electrical values and temperature values often need to be checked together. Instead of carrying separate tools for basic circuit testing and contact temperature measurement, you can handle both with one meter.

This is the right fit for HVAC and refrigeration technicians, maintenance teams, and service pros who need more than a simple current clamp. If your work includes troubleshooting flame sensors, checking supply voltage, verifying amperage draw, testing continuity, and taking temperature readings at equipment, this meter lines up well with that workflow. If you only need a bare-bones clamp meter for occasional homeowner use, this is probably more tool than you need. For daily service work, though, it is built with the right feature set.

Milwaukee 2236-20NST Clamp Meter for HVAC/R (NIST) is made for service techs, not casual meter owners

This is a well-targeted service meter that covers the checks HVAC and refrigeration techs actually make all day, with the access, display, and flame rectification capability to justify carrying it.

• Who it's for: HVAC and refrigeration technicians, maintenance pros, and service electricians who need current, voltage, temperature, and flame sensor diagnostics in one tool.
• Why it stands out: The thin jaw profile, 1.3 inch opening, True RMS readings, built-in non-contact voltage detection, and included NIST certificate make it more job-focused than a basic clamp meter.
• Worth knowing: This runs on AA batteries, which is convenient, and it includes the thermocouple and test leads. If you only need occasional basic amperage checks, you can spend less, but you will also get less capability.

• Is this a True RMS clamp meter? Yes. The Milwaukee 2236-20NST uses True RMS measurement for more accurate readings across a wider range of applications.
• What is the maximum current and voltage range? It measures up to 600 amps AC and up to 600 volts AC/DC.
• Can it measure temperature? Yes. It has a dual banana thermocouple input and a contact temperature range of -40°F to 752°F.
• Does it include a calibration certificate? Yes. This NIST version includes a NIST Certificate of Calibration with Data.