Hello, its getting pretty snowy and cold around where I live and I have noticed that whenever I use the rear defog button on my HVAC unit, only the rear window defogger turns on. Both the rear side windows have defogger lines so is this a temp dependant feature or is it something else? Ive tried using a multimeter to test for voltage and neither side has any voltage.

Any help will be appreciated thanks.

It all comes and goes all at once. , several lights on dash warnings lit several no comm thru according to obd2 port. Definite communication issue intermittent. Seems to happen all at once then back again. Ive unplugged cleaned connectors on fuse boxes in engine compart side dash and in driver footwell..Some come and go daily. Every ride is different every key start is different.