The wifes 99 concord lost heat. The fan turns on but just blows cold air. No leaks or coolant smells. Any suggestions???

 

Get the car nice and warm and run the heater even though there is no heat. Then feel the hoses running to the heater core. That will tell you if there is any flow through the lines. One will probably feel cool or just warm. Both should be hot, but not hot enough to scorch your hand.

Your heater core could also be air bound (causing no coolant flow), a sign of a leak.

When was the last time you serviced the cooling system?

 

Those things have plastic heater control valves I believe and over time they crack and allow the vacuum to leak, causing the valve not to open.

 

Where are the valves located? Can I replace with a cabled manual valve?

 

Have you checked the thermostat? Is the engine warming up or is it staying cool even after it runs for a while? If that’s the case then the thermostat may be stuck open not letting the engine come up to temp. It could be something as simple as just changing that out.

Just a thought.

Britt

 

Ran it till got hot. Only one line is hot, other is cold. I tried the park on hill, run w/ out cap on, trick. Still one heater line is cold. Is it still air locked? How can I unlock it?

Don't know when system was last serviced. There is no coolant smell. Please, suggestions on how to proceed.

 

It sounds to me like you may very well have a plugged heater core, disconnect the heater hoses and back flush with a garden hose from the side that is cold to see if you can unplug the core, otherwise you may need a new core. Also just wondering what the weather is like up in Wi? You guys already needing heaters?

 

^^^X2

Sounds like Your core is plugged but if you have one of the aforementioned valves check it as well. You can Bypass it and see if the heater works. Only problem is that hot coolant will flow through the heater core all the time.