I really appreciate all the help with my Blazer on this forum. I've had a slowly getting worse heater in my blazer. This winter I barely have heat unless the r.p.m.s are up and then the heat is minimal. My 4wd Blazer has 110,000 miles on it. I've put a new thermostat in and cardboard over the radiator. Still no improvement. I was thinking of flushing my radiator fluid next since it has never been done. What do you think? I have little ones and we are cold in the blazer so I really need to get this issue resolved. Its 5 degrees out today!!!BRRRR!!! Thanks in advance for any ideas for fixing this!

 

What temp stat did you install?

How is the air movement out of the vents?
Fan working just no heat?

Check the hoses to the Heater core
If one is a lot hotter than the other one your core is clogged
BOTH should be really hot when you grab them

 

I installed the 6 dollar thermostat from Autozone.

Fan works good, just little to no heat.

I'll check the core hoses this weekend. Where is the core on a blazer?

 

It is hidden waaaay up in the dash. The hoses you need to check are entering the firewall side by side about in the middle of the firewall, above and maybe a little to the left(facing the front of the vehicle) of the distributor.

After checking the hoses(which from your symptons sounds like the core just may be clogged), your next thing to check, in my opinion, is the mixer door. It has a small motor that goes out. It is behind the glove box and not real easy to get out but not to bad. You didn't say what year yours is and I am basing my info on a '97 and a 2000 that I own.

I would suggest you get a repair manual, they do come in handy on most stuff.