It was about 35 degrees this morning coming from work. I noticed that my temp gauge would warm up close to normal, but as I was cruising it went down alittle. Then as I turned on the heat the air came out hot at first and then started cooling off. The temp gauge dropped below the C. SO I turn the heat off and the car heats back up. So I turn the heat back on cause by now its freezing in the car again. Same thing happens. Any idea what this could be? Why is it over cooling when I turn the heat on?

Its was alot colder the other morning and I had no problem with my heat.

 

Check your coolant level, if not then it may be your thermostat starting to go.

aside from that I am nt sure because my 4th gen wagon does that as well and I haven't tracked down the problem yet.

 

Put some coolant in it today. It wasn't really low, but put alittle in anyway. I let it run for about 20 minutes straight just sitting still and the fan never kicked on once. It never overheated either. I'm thinking the thermostat is stuck fully open.

 

Yeah somthing is wrong with the thermostat if you fans didnt kick on in 20 minutes idling...

 

it's not ur coolant dude.... because it's so cold out, and the front of you car is open, u get a constant rush of cold air in ur engine bay, this makes ur motor cool down. If u want it to stay warm the whole time, u can do something as simple as placing a piece of cardboard infront of the radiator, so u don't get that freezing air under the hood. I have the same problems too, the only bad thing to this is that ur car kinda starts to overheat a little, thats why i took mine out, but in severe cold " like under 30 c " i'll put it back in. Truckers do this same thing, except they don't use cardboard, they have some special thing. Hope that helps

 

Yeah but hes in Florida...it doesn't get cold enough there to warrant the cardboard treatment or to have it justify this kind of fluctuation

 

yea but he said it was about 35 degrees outside, thats fairly cold i guess

 

It still does it if its 45 and 50 degrees outside. Thats why I let it sit still and ran it. So no air would be going through the radiator. I'm probably going to change the thermostat since it only like 5 bucks to see if that helps any. Now that I noticed the problem. I've noticed that it takes alot longer for it to heat up to normal temps. 35 degrees here is like a rare temp. Its usually in the mid 40's to 50's.

 

Well I fixed it yesterday. It was the thermostat, but when I was tighting the housing back down it cracked down the seam. So I had to order a new one from AutoZone. Only 11 bucks. Well now its fixed and just in time. It cold again today after being 75 degrees for a week.

 

my civics thermostat went out and i never knew it, but figured something was up when i got my accord and the shit would be hot by the time i got out to the freeway which is a mile away, but the civic would take like 5 miles out of town before it moved off c and then didnt go very high still ... gets to normal when its a bit warmer outside though.