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Unknown Command Error

When I select a Design Master HVAC command in AutoCAD, nothing happens. The command line shows an "Unknown command" error.​

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Cause​

This can often happen because AutoCAD has become corrupted. If you press F2 to view more of the command line and scroll up, you may eventually see a no function definition: VLR-Command-Reactor error:

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Design Master HVAC relies on, among other things, the AutoCAD function "VLR-Command-Reactor." If that function becomes corrupted, the software can't operate.

Solution​

You will need to repair, or uninstall and reinstall AutoCAD.

Instructions on how to repair/uninstall programs:

note

Afterward, your Design Master HVAC menus will probably be gone.

You do not need to reinstall Design Master HVAC; you just need to reconfigure the menus.