Been below 40 here many mornings so far this year. I want it fixed before it gets real bad.
Check the position of the Heated Mirror Switch.
There is a L, and an R for the adjustment of the Left or Right Mirror.
That leaves a "O" setting for off, and "Squiggely" setting for Heat.
Normally you would want the "O" (off) setting for daily driving.
If you had the incorrect setting, then over time you coul possibly have damaged the Mirrors*.
*The Heating Cycle is roughly 10 Minutes, but if you had the switch in the incorrect position, the would equate to a 10 minute cycle of heat every time you drove the car. Although the Rear Window Defogger will time out, the Mirrors may not time out.
There is the J99 Heated Mirror Relay, which could be suspect.
Relay Arrangements on relay panel at Vehicle Electrical System Control Module under instrument Panel, left
B1 (left) B2/B3/B4 just to the right of B1... B2(J99) Sub Code SHZG Relay Type 449