AC Unit too small in a rental?

I live in California and we rent a house from an individual. He is very problematic about fixing things. When we moved in he said that the ac worked great and that his pge bill was never over $100. Problem is he lied. The Air conditioning unit as is turns out is the size of one that would be used for a 2 bedroom apt according to the PGE rep. Do we have any options to force him to upgrade so our pge cost isn't through the roof? or should we start looking for a new home?