Hey, I am sort of new here, so hopefully this is in the right place. I have what seems to be a fairly significant coolant leak and I seemingly have run completely dry on more than one occasion. I've parked over white paper to determine the amount I'm losing and I only found 5-6 drops over the course of a weekend (parked the entire time). I'm hoping it's not a head gasket issue...

I'm posting here specifically because of a curious phenomenon I noticed today. The temperature gauge on the dash has never moved past the half way point and so it took me a while to notice that the coolant was an issue. But today (a last ditch attempt to get my windshield defrosted as the heating isn't working) I turned the internal air onto circulate and the temperature gauge jumped almost to maximum at the next red light I caught and then dissipated when I began driving again. No such effect with the circulation off. Is this just because it is pulling more air past the engine with circulation off and I have seemingly run dry on coolant again? I have put probably 3.5 L into it in the last couple months so that would be worrisome if it was the case.

And this no-heating thing has become a problem lately as it has been -30ish here lately and I might actually have frozen to death if it weren't for my heated seats. Are these likely related, and is there anything else I could look at to restore the heating?

Anyone have any suggestions for me?