I have a 2000 Neon, 145K miles. Last winter, the heater didn't work too well: With the air recirculation on, I could get about 125-130 degrees at the vent. But of course, recirculating air in the winter leads to foggy windows. With fresh air, the max temp was about 80.

I also noticed that the water temperature gauge was moving very little above 'C.' Thinking the thermostat might be stuck open, I replaced it, with no improvement. I then flushed the system, and refilled with fresh coolant. Still no change. I flushed again, paying special attention to the heater core. I also backflushed, and liquid flows freely through the heater core. No joy. I may have replaced the thermostat again, but enough time has passed that I'm not positive about that.

All spring and summer, of course, the water temp gauge was in normal operating range. Now it's getting cold here, and not much heat.

I don't know what else to do. Can somebody give me some suggestions/additional troubleshooting tips?

Thanks

Mike