MicroSquirt.com read only forum (Jan.15,2018)

I can’t speak for your situation, but the air conditioning vents/flaps runs off the engine vacuum. You may have created a leak when you fixed the air that wasn’t there before.

Bill Struble
Posted by email.

I have seen this happen when the communications parameters were set for for msi and msii processor was being used. IE 9600 instead of 115200 -- also have seen this when when msi was "set" when msii should have been. Check your software setup for megatune.