if as been suggested the thermostat is jammed open you can confirm this by feeling the hoses that go tothe heater unit these are normally 3/4" to1" thick if when the engine is at normal running temperature you feel these hose ( they willbe going into the bulkhead the panelbetween the engine compartment and the inside of the car)
The hoses should feel rearly hot as hot as the other engine hoses if you can bear your hands on them then you may have a thermostat problem but normally these jam Shut causing over heating not underheating
Whis brings me to your temperature gauge is this showing normal if so the most likely and common cause of your low heater output is that the cable that connects the dashboard to the actualwater flow contrale valve in the heater its self has become disconnected and soalthough you move the lever only the cable is moving and not controlling the flow intoand out of the heater
Unless you are familiar with the parts of a heater it is best toget someone that is to takea look butmy money is on a cable disconnected especialy if your engine temperature gauge is normal
Good Luck Roger
Roger, February 2008
