Hey everyone, this is a first for me. I usually read past threads and forums to figure out my issues, but am so confused my head hurts!!!!

I have a 2001Eddie Bauer Ford expedition that had zero heat all, with front and back heater core and control. Attempted burping system for 5 hrs straight with zero results. Replaced thermostat twice in 3 yrs. Initially had one one heater core hose hot and one cold for months, and was gonna attempted to flush heater cores when I realized that I had the same heat in the front that I had in the back, meaning if it was a plugged heater core, both would be plugged, not very likely. 3 days ago was a half gallon low on coolant so I topped off. Picked up workink on it today to investigate and was 2 gallons low on coolant!!! Filled up coolant today, and discovered a new leak that seems to be coming from radiator itself.. ( this is where I am now confused) since 3 days ago when I topped off coolant and leak began ( I'm assuming), my symptoms have completely flip flopped.. now both heater core hoses are hot, but not so much that I can't hold them, same temp.. and now all the sudden, I get a 20 sec blast of warm air when I initially turn on heat, as before I had ZERO heat no matter what!!! I am So confused that my head hurts and now have no idea what to try next!! I've read tons of forums that say, check heat control valve and ensure vaccum line is attached.. everything I read says expo does not run a heat control valve!! Do I completely Rip my dash apart to replace blend door??? I'm in no position to do all this work and money on "maybe" solutions!! Any advise would be greatly appreciated!!!!! Thank you

 

From the info you have so far provided, I would be concerned where the coolant is going and correct that first ! It is possible that due to a low coolant level air has replaced circulating coolant and when some coolant managed to get into the heater cores you got a brief dose of heat. Correct the leaking coolant problem and carefully fill the cooling system so most of the trapped air can get pushed out.
I believe this explanation makes some sense and it should be worth a try,give it a shot and let us know how you make out .

 

Amanda , what size motor do you have? How many miles also.