Have Ford Questions? Ask a Mechanic for Answers ASAP
Hello and thank you for your question,Before you start pulling parts can you go out under the hood and while the heater is blowing cold see if both heater hoses are getting nice and hot?
The hoses that you need to check are the two that run directly to the heater core at the firewall , both should be to hot to hold , are the the hoses you checked?
Okay then you mechanic is very likely correct providing you are sure you have good flow through the heater core. Ford released a Service bulletin that calls for removing the AC/heater plenum and replacing a warped door. That may very likely be the problem you are having. I have enclosed the bulletin in the link below for your review, copy and paste the link to your browser to open and view it.https://dl.dropboxusercontent.com/u/104923897/Blend%20door%20TSB%20Nov%206.pdf