My heat stopped working last week in my 2005 Grand Prix. We changed the thermostat and everything worked fine. Yesterday I noticed the temperature was running higher than normal (1 line past halfway) but the heat was working. Now the temperature is still running at that same mark but the heat does not blow out cold.
When I changed the thermostat, I added a little coolant to the overflow because I thought it was low (couldn't see the marks on it). For 2 days I could smell antifreeze when I got out of the vehicle but now it has no smell and the level in the overflow is back to where it always stays.
Any suggestions on what to try next? I saw a post that said to flush the heater core. I'm not sure how to do that. The whole system may need to be flushed as I have never flushed it and it has about 100,000 miles on it. Someone told me it could be the sending unit but I can't find any information about a part like that on this car.
Any help or suggestions would be appreciated. Thanks!
