Klein Tools CL450 Electrical Tester, HVAC Clamp Meter with Differential Temperature

Yes, that's what the CL450 is built around. It has two K-Type thermocouple ports, so you can read both probes at once and get the differential temperature directly instead of taking one reading, moving the probe, and doing the math. It ships with two K-type thermocouples in the box. Range is -40 to 1832 degrees F (-40 to 1000 degrees C), which covers supply/return air, refrigerant line temps, and flue work.

The CL450 carries a CAT IV 600V and CAT III 1000V rating, with Class 2 double insulation. CAT IV covers the service entrance and utility side, CAT III covers distribution panels and feeders inside the building, so it is rated for panel work, not just receptacle-level branch circuits. Never put it on a circuit above the category rating it holds.

The clamp jaw opens to 2 inches (5 cm), which takes typical single conductors and most feeder cables you meet at an RTU disconnect or a condenser whip. It will not go around a bundled multi-conductor run or a large parallel feeder set larger than that opening. Current measurement through the jaw is 600A AC, auto-ranging TRMS.

Yes. The CL450 has a dedicated inrush mode that captures the startup surge rather than averaging it away, which is what you need for compressor and blower motor LRA checks. It also holds Min/Max and AVG, so you can leave it clamped and come back to what it saw.

It does, and that is the reason most HVAC techs pick it over a general-purpose clamp. The CL450 reads DC microamps to 200 microamps with 1 microamp resolution, which is the range a flame rectification signal lives in. You break the sensor lead into the meter with the test leads for that reading, not the clamp.

Yes, two ways. Low impedance (LoZ) mode loads the circuit down so a phantom reading induced from a parallel run collapses to near zero, while a live circuit holds its voltage. The low-pass filter strips high frequency noise off the reading, which matters on VFD-driven equipment. Both are on the CL450 alongside AC/DC voltage up to 1000V.

Read the fine distinction here before you order. The clamp jaw on the CL450 measures AC current and inrush only, so DC amps through the jaw is not a function it has. DC comes in through the test leads: DC voltage to 1000V, DC millivolts, and DC microamps to 200 microamps. If you need DC amps around a conductor, for solar strings or battery banks, this is the wrong clamp and you want a DC-capable clamp meter instead.

The CL450 comes with a carrying case, instruction manual, straight input test leads, two K-type thermocouples, and 3 x AAA batteries, so it works out of the box for delta T and electrical readings. Bought separately: the K-Type Temperature Pipe Clamp Cat. No. 69140 for strapping a probe to a refrigerant line, the K-Type Temperature Probe Cat. No. 69144, and the Magnetic Hanger Cat. No. 69417 for hanging the meter off a unit while you work.

Yes. Capacitance measurement goes to 6000 microfarads through the test leads, which covers run and start capacitors on residential and light commercial equipment by a wide margin. Discharge the capacitor before you put leads on it.

For most HVAC service work, yes. The CL450 clamps 600A AC and handles the full multimeter side through the leads: AC/DC voltage to 1000V, resistance to 60 megohms, audible continuity, diode test, capacitance, frequency to 999.9 kHz and duty cycle. Duty cycle and frequency are what you want for ECM blower and VFD troubleshooting. The gap is DC amps through the jaw, which it does not do. Display is a dual backlit 6000 count LCD, so you can read it inside a dark mechanical room, and it has a DC polarity indicator and data hold.

Klein Tools CL450 is the manufacturer part number, sold as a single configuration with no finish or range options to specify. Klein's naming for it is the HVAC Differential Temperature Meter. If someone hands you a spec calling for a two-port K-type clamp meter with inrush and DC microamps, CL450 is the number.

It is rated for a 6.6 foot (2 m) drop, which is roughly a fall from a step ladder or off the top of a rooftop curb. Body is plastic and electronics, 12.5 oz (354 g), and it comes with a carrying case. Auto power off is built in so it does not drain the AAAs if it gets tossed in a bag switched on.

It runs on 3 x AAA batteries, standard alkalines you can stock on the truck. Klein lists replacement parts 69401, 69435 and 69410 against the CL450 for lead and accessory replacement, so a chewed-up lead set does not retire the meter.

The CL450 measures 10.00 x 3.77 x 1.59 inches (25.4 x 9.6 x 4 cm) and weighs 12.5 oz (354 g). That is a full-size clamp body, so it goes in a meter pouch or the supplied case rather than a shirt pocket. If you want it off your hands at the equipment, the Magnetic Hanger Cat. No. 69417 is sold separately.