Problem ith Lnadlord repair

The house that I rent has central heat and air in it. In December 2010, my electricity Bill was 387 dollars compared to the previous month when it was $128.00. I went to my landlord and told him this and he told me it was due to climent changes. I asked if he would still send someone out to fix it. It took him 3 weeks to get anyone out to do the repairs and when they finally came they said that my heater and air conditioning unit were running at the same time due to a wire being broken in the unit. My landlord now refuses to help pay my electricity bill. I think that because his unit went out and there was nothing that I could do, and the fact that there was no way of knowing that it was broken, he should be obligated to pay atleast half of the bill or take it off my rent. He told he (he is a lawyer) that I need to find a law requiring this of him because otherwise it is not his responsibility to pay the bill. My question is is there any LAW in Oklahoma that protects me as a renter and requires him to pay a portion of the bill since it was his unit that went out?