Over this winter period, I noticed that the temperature of the heat within my 1992 Mercury Tracer was slowly diminishing and that the temperature gauge rarely went past the "C" mark. After initial fault finding, the signs seemed to point to a problem with the thermostat. I subsequently changed the thermostat twice (I thought that the first one that I purchased could have had a factory defect) and it still did not resolve the heat issue within the vehicle. As well, approximately a month ago, I replaced the heater core (there was a smell of antifreeze when the heat was turned on) and have thoroughly flushed the radiator, heater core, and engine block. To give you some background, I live in Winnipeg, Manitoba, Canada and during the past couple of months, the temperature has dropped between -40 to -50 degrees Celsius (Wind-chill included), but this does not seem to have a diverse effect on the temperature of the heat from my other two vehicles (even my 1969 GMC truck blows out hotter air). The other interesting thing that I noticed was that when I had the blower heat control levers to the extreme left position (i.e. cool, internal air, and panel), I would sometimes see a slight rise of the temperature gauge from the "C" to the "N" in the normal range. Any help or insight in regards to this matter would be greatly appreciated, as obviously the cold temperatures and minimal vehicle heat are a dangerous mixture.