I have a two story house with 1 thermostat up and one down. Down is on zn 1 liek it should be and 2 ofcourse is up. Suddenly the AC will only blow air through 1 zn at a time. If the upstairs is on and running the downstairs will not blow. If the downstairs is running then the upstairs will not blow. I have a Zone Thermal Equalizer mod# ZTE2S that was installed by Beutler. Anyone with any ideas please respond. Thanks!