why do i read 35vdc and 12vdc until i plug in indoor split unit

Thread Starter


Joined Mar 1, 2018
Hey guys I could really use some advice. I have a spilt unit hvac system. the unit on the roof has a power supply from 120v to 35vdc and 12 vdc which goes into the indoor unit. my problem is when I plug the dc voltage out to the indoor unit I no longer get a steady dc voltage reading. if I unplug it the dc out remains constant. Any ideas?

indoor unit disconnected I read 12vdc to common and 35vdc to common
indoor unit hooked up. do not get any accurate reading. just jumps around

This unit is 120v 60hz