The control head is a plug-in part. Access it by carefully prying off the plastic trim around the climate control and radio. The trim snaps on in several places. You may find control heads in junkyards, but most have the same problem with the hot on one side/cold on the other that is discussed frequently on this board. New ones aren't much better. I replaced mine under warranty at the dealer, and it was worse than the original, so I had them reinstall the old one. The issue is a design flaw with the controller and temp sensors.
You have to take out the whole heater and air condiasioning system out and replace the new heater core in. When you replace the heater core, you firset have to put the air condiasoning system in then the heating system/ heater core. When you take the old systems out, you first have to take out the A.C then the heater.
One of these things is the cause. Thermostat stuck open, replace it. Heater core stopped up, backflush the hearter core, and service the cooling system. Heater temperature control valve defective, replace it.
Either the heater temperature control valve is not working, the heater core is clogged, or your thermostat is stuck open. The car is 9 years old. If you have not serviced the cooling system in a few years, then drain and flush the system with the heater control set to hot, replace the thermostat, fill with a 50/50 mix of coolant & distilled water. Be sure and bleed all air from the system.
There is no short cut or fast way to do this. The dash has to come out to access the heater box and replace the core. So the steps in replacing the heater core are to disconnect the heater hoses, remove the dash, to access the heater core cover on the front of the heater case and replace the core. Reassembly is in the reverse order as disassembly. Fill the cooling system with new coolant, and burp the air form the cooling system. There is no short cut or fast way to do this. The dash has to come out to access the heater box and replace the core. So the steps in replacing the heater core are to disconnect the heater hoses, remove the dash, to access the heater core cover on the front of the heater case and replace the core. Reassembly is in the reverse order as disassembly. Fill the cooling system with new coolant, and burp the air form the cooling system.
Most newer model cars the only way to replace a heater core is to completely remove the dash to access the heating system ducts as well as the core.
There is no heater control valve fitted on a Ford Escort. The heater matrix is directly connected to the engine's cooling system. To reach the heater matrix, you should remove all the facia unfortunately... :(
If your heater isn't blowing any hot air when you turn it on and set it to hot, most likely the thermostat is faulty. It is also possible that you have an air bubble in the system (bleed it), the radiator is plugged (replace it), or the water pump is bad (replace it). As far as using the heater to test the system, that is sometimes unreliable because either the lines to the heater core are plugged or the control valve in those lines is jammed.
If your heater control is manual you probably have a cable that has become disconnected at the heater control valve or on the back of the panel. If you have an automatic temp control system you probably need a new temp control panel.
There is no short cut or fast way to do this. The dash has to come out to access the heater box and replace the core. So the steps in replacing the heater core are to disconnect the heater hoses, remove the dash, to access the heater core cover on the front of the heater case and replace the core. Reassembly is in the reverse order as disassembly. Fill the cooling system with new coolant, and burp the air form the cooling system. There is no short cut or fast way to do this. The dash has to come out to access the heater box and replace the core. So the steps in replacing the heater core are to disconnect the heater hoses, remove the dash, to access the heater core cover on the front of the heater case and replace the core. Reassembly is in the reverse order as disassembly. Fill the cooling system with new coolant, and burp the air form the cooling system.
You may have a clogged heater core, or a leak in the system somewhere. Take your car to a mechanic who can replace the heater core or diagnose the leak.
You most likely require an A/C system recharge. There should be a temp sensor under the hood near the passenger firewall connected between heater hoses to control the ac and heater temperature. Replace that first.
Low coolant in the system. Defective heater control valve. Clogged heater core.