I was just wondering if the 06 base model with non bose system has a stock external amp somewhere? the reason why i am asking is because

I recently had my avic d3 go bad... and i thought it was the pioneer headunit... so i returned it to get it fixed from pioneer. i got it back and the problem occured again. after returning the pioneer avic-d3 back to pioneer for the 2nd time. the stereo shop installed back the old nissan stock radio... and after 1 week while driving in the freeway in a hot weather... the problem occured again with the stock radio. the radio works but there is no sound from the interior speakers. and after like 15 minutes later.... the radio worked again....

the problem is when the weather gets a little hot and i park my car outside.... the headunit will work and the screen displays and everything but there is no sound for my internal speakers.... but i do have my sub hooked up to another amp.. and the sub is working fine....

any help will be appreciated. thanks....