Hi, I’m having a strange problem with a Cavalier Ecotec 2005 only when it's cold outside (under 0C ). When I’m starting the heater blower, the engine is losing heat. It's even worse when I’m on the highway, the engine is running cooler. Also strange thing, the radiator fan is always running. It's cold there, we get -35C in winter so it's a pain to not have a working heater and also the engine is running cold, so it's not good. I have replaced the thermostat but I have the same problem. Don't know what to think; maybe the heater core is clogged?

So is it a cavalier or sunfire?

Lol^^^

Could be plugged or the heater valve is stuck/malfunctioning.. Not sure how exactly these operate since i never had problems with mine.. Maybe you could try blocking off part of the radiator and see if it holds heat better.



Edited 1 time(s). Last edited Sunday, January 27, 2013 8:19 PM

Have a nice day.

Stupid question but your coolant filled enough?


black 03 z24 with a few mods

I would first drain the cooling system and flush with some lime away(yes lime away) it is safe to use.Just drain,fill with water and add one bottle,and run up to temp with heat on,and fan high.I place cardboard in front of the radiator to speed the process.Run for 15-20 min at idle with rad cap off(or if no rad cap your overfow cap off).This helps air escape and then drain and refill with water only and do the same time and then drain again.Then mix your coolant to ratio with distilled water and see if that helps.Unless your heater core is blocked up,hoses causing a restriction or even a faulty NEW thermostat can be a problem.At the temps your describing it takes longer for the engine to reach normal operation and if your cooling fan is running constant is a issue I would check your fan relay or could be a bad fan idk with the 3rd gen stuff specifically.Just making recommendations based on general problems and yes placing cardboard blocking half of your radiator can help alot to reduce cold air flow when everything is working RIGHT to start with.I do this on one of my rides which is prone to cold air reducing heat and everything is 100% right just speeds heat process and stays warm better on stupid cold days.And unless your waterpump is not circulating at it's optimum performance could be a thought.

Just throwing this out there. Not sure if it's even possible on these cars, but is the thermostat installed the right way? If it were backwards, I would think it would cause an overheating problem, but who knows the way things are built these days.





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