88 e300 temp gauge dead,how to test

[olpos]

hi ,well just bought a 88 300e in very nice shape. what a great driving car !well temp gauge does not work and was wondering if there is a test of the gauge itself.on alot of american cars i can ground signal wire at temp sender, for a quick second,and the gauge inside car will swing to hot. if so which wire do i try. if gauge inside car is bad is it a nightmare to fix? do i need to send out insrument cluster for repair?
also my climate control does not light, are they easy to get to bulbs?
tried the search ,but could not find the right words
THANK YOU Rich