Are you sure it's not a bad blend door actuator?

 

yes im pretty sure it isnt, cause one hose going into the firewall is warm and the other isnt at all..... thats what led me to the heater core....

 

The heater core is easily air locked,it is about the highest point in the system.
Is your coolant level correct?
The fittings are quick release,takes a special tool to release them.At your local parts store.
Pull the hoses off,and use a garden hose to flush the core.
Usually there is a gurgle as the air comes out.Fill the hoses with coolant,and clip back on the fittings.Fill the coolant tank,and you should be good to go.

 

If it is completely clogged, I'd say it's going to have to be replaced.

 

I have fixed several trucks,and have yet to find one totally clogged.Usually flush them both ways,and it works well.Usually not much comes out,some little rusty chunks.
It is usually air locked.The air will compress,and not allow the flow of coolant,or slow movement at best.
And,it is a major job to change a heater core.Most of the dash has to come out.

 

Yea, it's a big job to replace them. I have had worse luck that you when trying to clean out plugged cores. Usually, it I am able to get them flowing, they will begin leaking. I guess you can try to unclog it, but I'd bet you will be replacing it soon afterwards. Like stated above, make sure it's not got an air pocket in it first.