My single lever kitchen faucet (delta or mohen) has hot water and warm water coming from the faucet. When I turn it to cold warm water comes out. What do I need to do? We can not find any problems with the connections. Any help would be appreciated.

Turn the water off.Remove the small plug(with the manufacturers design on it) or the top of the handle(however you can to remove the insert from the base)some require an Allen wrench,others are screws)

Look closely at the washers,the plastic or metal surfaces,look for any wear or bright spots showing a loose fitting,a warn out washer,a broken set.. if possible,take it to a local hardware or plumbing store and ask for their opinions(the hardware would be less expensive for the most part,but might not have the replacement you require if this is a better model faucet)

Good luck.