Well friday morning on my way to work I thought I caught a whiff of coolant in the air as I was driving in. It was very faint and I didn't notice it again so I didn't make a point of it. Last night however it was quite cold out and I began to notice the smell again, then the windows fogged up badly, and would not defog. The heat coming out the defrosters was still very warm and the truck heated up quickly this morning. So i've come to the conclusion that I have a leak in my heater core. I'm just wondering what I'm up against here and if anyone has the diagrams for pulling the dash apart and such. I searched the forums and it sounds like a bitch of a job to do. Tomorrow I'm also considering buying some stop leak and running that through the system. Has anyone had any experience with using this stuff for a heater core leak?

Another thing I noticed is that the AC compressor is not running all the time that the defroster is on, is it not supposed to be?

 

I wouldn't use Stop Leak or anything like it. Yeah, the core is a bear to change. The compressor should not run constantly on defrost, just like it doesn't constantly for a/c. It turns on and off as needed.

 

Stop leak is an emergency, temporary fix that will end up plugging the small tubes in the heater core and the radiator. I recommend replacing the heater core.
Here's a thread on heater core replacement that I hope will help. It's a long post so I'm not planning on retyping it.
https://blazerforum.com/m_33134/tm.htm

 

I would recommend replacing the heater core as well, its not that big of a bear to do but it can be a pain!!

 

well I ran the barrs leak through it and it fixed it within 5 minutes. I've heard conflicting results about it but I decided I would do it so it was driveable. There is still a good chance that I may end up replacing it though.

 

Check it again carefully when the weather warms up. If you have to replace it, it would be nicer to do it in the summer than when it's freezing outside.

 

When summertime hits and your not using your heat replace the heater core and flush your system out!! That stop leak can mess up your cooling system!!