heater core

i dont think your heater core is the problem.have the thermostat replaced.they will often stick open causing no heator stick closed causing no heat and boiling over,ps do this job with engine cold and replace every 3 years and with fresh antifreze.

Yes, also check any applicable heater control valves in the lines going into the heater core. Your heater core is located deep inside the dash, and is a rather complex job to replace. The lines running into it are on the passenger side of the engine compartment. The heater control valve would be in these lines.

Although the question is 7 years old I'll outline what I found to be the problem in my '87 Camry LE: In a nutshell the connection fingers behind the control box you change fan speeds with which control the 'servo' which moves the valve on your firewall from heat (in) to out (cool) have either corroded or have cracked over time where they connect to the computer board. On other words, there is a lack of 'continuity' in the switch when the slider for heat or cold is moved. It defaults to cold for what ever reason. The fix is as follows: Take out the cigarette can, undo the two screws which hold the AC control frame in place, pop out the frame ( two clips at bottom ) and just rest it aside still connected to the cigarette lighter. Undo the screws holding the control box in place and wiggle it free. Behind it you will see two connecting plugs, pry the plugs off by holding the center clips. They will be tough to move but they do come off. The problem connectors are the first four fingers for the large plug as you view it from the front. To fix the connection you have to torque those fingers just a little to regain proper contact. Here's how: Spray some contact cleaner on all the control fingers and inside the plugs. Next wrap some thin wire around the large plug and make it tight. Now with controller in hand drill a 1/4" hole in the black plastic right above the four fingers I spoke of earlier. Now, put the plugs back in the controller box- seat them securely. Take a 'ZIP' tie and go from the hole you drilled to the wire you've wrapped. Pull that tie tight but don't over do it. The torque will make the connection happen but test it by starting your car, popping the hood and see if the heater valve on the firewall moves in from heat or out for cold. If it does go grab a Kleenex because you'll need it to wipe the tear away from you're eye when you realize you've solved a problem that you thought was going to end your relationship with your Camry. Enjoy the heat!