That's good to hear...especially knowing that it was under warranty!
Originally Posted by spork
Well...that sucks. I guess my first question would be... why did they replace the thermostat during a heater core replacement? It's possible that Mitsubishi tells them to do this as part of the job...or maybe they experienced the same thing you are seeing now (no heat) after they put it all back together...so they just threw a thermostat in it. It wouldn't be the first time a dealership threw parts at a problem without diagnosing it.
...the car engine/coolant (measured by ultragauge) was not getting as hot as it should at all.
...The paperwork they gave me also states that the thermostat was replaced.
Keep checking the coolant level to make sure it's full. It sounds like either the thermostat still isn't working properly or maybe they didn't bleed all of the air out of the cooling system when they put everything back together?!? An air pocket in the wrong place can cause some strange results.
In any case, it's not your problem. Take it back and they will have to sort it out.
View my fuel log 2015 Mirage ES 1.2 manual: 52.1 mpg (US) ... 22.1 km/L ... 4.5 L/100 km ... 62.6 mpg (Imp)