Cold Weather Heating Problems

[JohnD1079]

I made sure the heater valve is working and that the coolant didnt gel.

Basically, whenever it gets really cold (below freezing) my heat does not work as well as it did before. It starts of nice and warm, but after a while it dosent get warm and gets colder. The faster I drive the colder the air gets (Its not as cold as outside, but its not warm either). Yesterday(It was like -20c out) I was driving on the highway for a while and it was soo cold that frost built up on the inside off all of my windows. I had it on heat with the fan at 3 on the defogger and it could barley defog it. (If I put it on higher fan speed it would just blow out cold air). When I got to my destination, I popped the hood to check if all the hoses were hot and the cooling fan came on. I havent driven my car in 3 months time, so I may be off here, but it also seems that the temp guage is a little bit lower than I remember it.

Another thing. Whenever I drive in really cold weather for an extended period of time, whenever I put it in neutral the idle jumps from 1->2k. This only happens when Ive been highway driving in the really cold weather. It has to be some valve on the Intake manifold. Any Ideas?


All my research says that my heating problem is a clogged heater core. Any way to check it or try to unclog it without removing it?

[dj_ender]

I made sure the heater valve is working and that the coolant didnt gel.

Basically, whenever it gets really cold (below freezing) my heat does not work as well as it did before. It starts of nice and warm, but after a while it dosent get warm and gets colder. The faster I drive the colder the air gets (Its not as cold as outside, but its not warm either). Yesterday(It was like -20c out) I was driving on the highway for a while and it was soo cold that frost built up on the inside off all of my windows. I had it on heat with the fan at 3 on the defogger and it could barley defog it. (If I put it on higher fan speed it would just blow out cold air). When I got to my destination, I popped the hood to check if all the hoses were hot and the cooling fan came on. I havent driven my car in 3 months time, so I may be off here, but it also seems that the temp guage is a little bit lower than I remember it.

Another thing. Whenever I drive in really cold weather for an extended period of time, whenever I put it in neutral the idle jumps from 1->2k. This only happens when Ive been highway driving in the really cold weather. It has to be some valve on the Intake manifold. Any Ideas?


All my research says that my heating problem is a clogged heater core. Any way to check it or try to unclog it without removing it?

Awww, I'm not blocked anymore.....sooooo sad. Anyways, i would trend to think the same thing, if it's plugged no hot coolant passes thru it, therefore no heat. i know of no way to test it. The only other thing i could possibly think that could be is air in the coolant system. Just my .02

[S Swap]

Another thing. Whenever I drive in really cold weather for an extended period of time, whenever I put it in neutral the idle jumps from 1->2k. This only happens when Ive been highway driving in the really cold weather. It has to be some valve on the Intake manifold. Any Ideas?

I'd focus there first. Check for air bubbles or low coolant. Also take a look at your thermostat.

Those things are much much easier than doing a heater core.

[RustyBucket]

As ^ said, check for bubbles in the coolant and check your thermostat.

If it's warm when you start off, then your heater core is probably not clogged.

When you are driving and the vent temperatrure gets cold, which way does the temperature gauge on the dash go? If it goes up (especially if it suddenly overheats), check for bubbles in your coolant. If the temperature gauge goes down when the vents start blowing cold, then check your thermostat.

Do you hear any gurgling noises coming from under the dash after driving it? If you do, then it's air in your system.

I had a Legend that showed the same symptoms with the heat blowing cold pariodically. In my case, very soon after the vents started blowing cold, the temperature gauge would go into overheat. There were air bubbles (caused by a bad head gasket) that would get into the heater core, causing it to blow cold and also get trapped behind the thermostat, causing it to shut and the engine to overheat. I could bleed the coolant to fix the problem until enough bubbles built up in the system to make it happen again.

btw... bleeding coolant at -30C is no fun.