electromic mirror

I can' t figure out why my compass works fine on my mirror, but not the temperature . Any ideas on what to check?

Faulty thermocouple or shorted wires coming from it. Or the mirror could just be bad.

I got a 97 Tahoe, and it has only compass, no temp i rear mirror. What do I need to do/change to get the temperature in the mirror also? Is this possible?

A shorted Thermalcouple with show SC on the mirror and an open circuit will be OC. Also, if one of the buttons on the mirror does not say TEMP, you do not have the temperature feature and there is now way modify the mirror to get it. You'll have to get one with the feature, sorry, try E-Bay.