Heater mostly not working

[Polonius]

I've finally been driving with it cold for long enough to figure out some of the habits of this problem. Last year, I could get warmish air as soon as the engine temp started up past the cold line. This year it's been terrible, and for most of it I attributed it to not being able to plug in the block heater at the new job. But it's not that. I threw some duct tape in the grill early in the year to block more airflow, and it didn't help.

So, according to my dash thermometer, my engine is heating up just fine. In fact, if I idle for too long it'll go up almost to the hot line. It never did that last year. But even when it's that warm it's fairly rare for the heater to be blowing warm. When it's that warm, the radiator feels quite warm and the fan will work in a normal seeming way - but no heat. In fact it seems like the -30 days are much more likely to get near overheating that the -20 or warmer days.

When the temp is right in the middle where it normally is, I can sometimes get warm air - it's about half the time though.

I should mention my normal usage of the car - 7-10 minute commuting. Out of a heated garage in the morning, and 5-15 minutes of running time before driving in the evening. The once or twice I have to grab some shopping, the heat does seem to be more regular after I've been driving (vs idling) more. However, given the same length commute last year, I had regular heat last year.


I have done no cooling system maintenance to this car since I bought it over a year ago. I assume whatever I do is going to include a coolant flush. Anything particular I need to pay attention to when buying coolant? Or just grab the cheap green stuff at Canadian Tire?

I've checked the heater core hoses after driving home today. I was getting a little heat most of the way, which is better than usual lately. The hoses felt fairly close to each other in temperature, and both felt nice and warm.

I've been through the manual two or three times in the last month trying to figure out how the system works, and am still a bit hazy. I'm not sure what that water thermoswitch is for - maybe to turn the rad fan on? The thermostat allows coolant to go through the radiator, right? From what I can tell, coolant goes through the heater core 100% of the time. (My friend suggested checking for a valve that stops/allows coolant through the heater core circuit, but I don't think we've got one.)

What should I start looking at first?

[Ryan]

#1 cause of this is low coolant level.

The cooling system works on many parallel circuits. Its confusing, and I've never gotten around the memorizing it.

#2 is plugged heater core, but since both the hoses are warm, you're probably alright.

I know personally that my car doesn't heat unless its at operating temp which takes usually a solid 20 minutes in our weather. Block heaters help, blocking rad helps.

A coolant flush never hurt anything, its cheap, so I'd go ahead and do it.

[Polonius]

Holy cow, Ryan! You're fast.

I was just out looking at things (you'd think I'd do that more often having a heated garage, but it's expensive to heat much above freezing! So I still don't do it much.) Anyway. No codes, in case that ever becomes relevant. I checked the coolant reservoir, and it's a bit above full. I checked in the rad cap, and couldn't see fluid quite there. So I dumped some in put in almost a liter before it started to gurgle. Then I put in nearly another half liter waiting for it to gurgle down. Then I realised I was doing it wrong. (at least how I was reading the manual). So I started her up. Sure enough, before it had gotten warm, out the coolant starts flowing! Grabbed a container and caught about a liter until it was right warmed up. Then I stopped it, put the cap back on, and started it up again. Blipped her up several times for about 5 seconds to around 2200 RPM as the manual states. Will let her cool down and then I'll top up the rad in the morning.

I think I've done a screwy job of it, but am I on the right track now if I keep bleeding the air out?

And is this low coolant likely due to a problem leak? or more comparable to those really slow oil leaks that no one bothers about? I have imagined early this winter that I could smell the faintest little bit of coolant in the interior heat. But not really the fogging up problems that are associated.

[Polonius]

Well, I had heat going to work today! Awfully nice. I think I'll keep topping it up after my commute til it stops taking any or until the reservoir starts getting fuller.

As far as I know, that only leaves me with a question of what to look for in the leak issue.

[Ryan]

If your exhaust is excessively white and couldy, you might be burning it through the head gasket(s).