I'm looking to see if anyone has any ideas about what might be causing my situation. My 2000 blazer LS used to blow some of the hottest heat in the winter of any car I've ever been in, then two winters, it started blowing cold mid winter, I had a mechanic "blow out the core" which caused it go back to blowing hot again. Then last winter, did the same thing, only this time, blowing out the core did nothing. For the rest of the winter, it blew cold.
The odd thing is that it is getting slightly cool again (40s-60s) and now its blowing hot again, but I am sure that once it gets really cold (0s-30s) it will blow cold again.
Any one have any ideas? I have a new son, so I need to fix it for good this time, can't have a newbord riding in a car at 15 degrees.
Thanks.

 

If this is a reoccuring thing, then you mostlikely have junk in your cooling system. By flushing the heater core, you have fixed the immediate problem, but did not cure it. To properly fix this problem, the entire cooling system needs to be flushed. At that time I would recommend a new thermostat and a new radiator cap. It is also a good time to do a cooling system pressure test to see if there are any leaks in the system. If the pressure bleeds down, then you have a leak somewhere. A leaking cooling system can lead to some very bad things!

 

swartlkk, thanks for the information, would that be something i can do myself? I have no problems doing the work, but I am a slight novice or would it be worth it now, as it has been going on for a few years to have it done professionally.

 

You could definitely try it. I have posted the procedure a few times now, let me see if I can dig it up.

Here ya go: "How to flush a radiator"

There are also some other posts that have some other information in them if the link above doesn't answer all of your questions. But post back here and we'll help out the best we can.