78 300SD, 116

I need heat, at least to defrost the windshield.
My amplifier is dead.
Do I need a good amp if I just want to bypass the
servo and give DEF heat?
I think the one in the parts car is good but if I dont
need to pull it, I wont. But if it's needed in order to
have heat, then I will just replace the amp and have
real heat. Servo is good, I believe.
I could hear the amp doing untoward things before it
died.

Thanks!

__________________
Ginny in Denver-ish
78 300SD, 265K (mine)