1999 Ford Expedition 4.6l blows warm not hot

I had a ford dealership attempt to fix this problem. They replaced a front heater core and thermostat that was suppose to fix the problem. Rear blows hot air what else could be wrong. I do not have anymore money for the dealership to keep taking and not fixing the problem.

It’s probably the famous issue with the electric blend air temperature door.

Is that hard to fix and is it a DIY project. If not approximatly how much is this going to cost me.

First, you need to verify what part of the system is at fault. If it’s the air door its self (which it often is) then it is very difficult to replace because the whole dash has to be taken apart. However, there is a shortcut repair that works for some. Go to a Ford explorer forum and search and you will probably find it.