No Heat Help

My heat is only warm. The temp gagues read fine replaced the thermostat and that did not help. Not sure what I should do next any Ideas?

Your heater core may be plugged up, not allowing the coolant to circulate through it.

If you don't mind making a mess, maybe detach the hoses to the core at the firewall and try to reverse flush it with a garden hose... just don't use too much pressure ;)

Search around this forum. I know I have seen posts before about people cleaning out their system with various products.