Zebra Instruments Masthead

Variable Speed Zebra

VZ-7 Photo Larry Demonstrating

The Variable Speed Zebra (Part VZ-7) is a comprehensive tool for working with ECM Motors and the circuit boards on the furnace or air handler that they require to operate properly. A training and educational DVD is included with each VZ-7.

The Variable Speed Zebra operates in-line with the system, in real time, testing both major sections (motor and control circuit boards) simultaneously.

the Variable Speed Zebra's primary uses

• Accurately diagnose exactly which component has failed in a Variable Speed system that isn't working correctly

• To assist in system setup by reporting CFM airflow (and RPM) as room vents and other controls are adjusted

• To allow easy experimentation of all of the adjustable settings and options available on the Variable Speed Motor; to allow optimum customer comfort


Control Panel

The Variable Speed Zebra's control panel has only 4 switches, and is simple to operate. It is microprocessor controlled - letting you concentrate on the system, instead of learning a complicated tool. The LED's in the blue section on the left report the status of signals coming from the equipment's controller board (left) and going into the motor (right). The digital display reports CFM, RPM, Volts, and any error codes discovered. Low control voltage is indicated by a flashing LED. Tri-Color LED's indicate the options currently selected on the equipment's controller board.

Currently, the range of popular tools to understand these motors leaves something to be desired. ECM motor manufacturers report that fully 41% of the motors returned to them as "defective" actually have no problems at all. As you may know, these motors are expensive; mis-diagnoses can add up to a lot of money quickly.

That statistic says that today's Techs may not fully understand what's going on with these systems - and no wonder! - with as many as 21 wires connecting these motors to the control circuit board in the furnace or air handler, most Technicians don't have the time (and often, the charts) required to monitor the various voltages and waveform signals going on in multiple lines simultaneously. The January 2006 - 13 SEER efficiency ruling made these energy-saving motors much more popular than ever before.

the Variable Speed Zebra

• Is contained in a rugged carry case with handle, hinged lid, and latch
• The VZ-7's wire harness are stored inside the case for protection
• Has an instructional DVD, and an operator's manual
• Has a laminated quick-reference card printed on the inside cover
• Is powered by the system - it requires no batteries.
• Has a one year limited warranty. Out of warranty service is available

Sales Demo Movies:

1. Introduction (2:10) Click here

2. Comments to Distributors (2:15) Click here

3. Specific Instructions (11:29) Click here

4. Windings Test (5:07) Click here

5. Final Comments (6:19) Click here

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Copyright 2005 Project Seven Development