Ok a few days ago my heater in my 2000 blazer ls 2dr was working fab. Then today when my girlfriend and i get done at a police class my heater just blows cold. Please help me. thanks.

 

First thing to check is that your coolant is full in the rad.
Check it when the engine is cold.
If the coolant is full, run the engine and check the 2 heater hoses at the firewall. they should be the same temperature. If one is hot and the other is cold, your heater core is plugged.
If that's the case, you might be able to flush it.
Tell us what you find,and we'll help out.

 

alright im going to do that now.

 

ok i checked the coolant level it was low. i let it warm up it was still low. I went to Advanced autoparts and got some 50/50 dexcool antifreeze put that it. and its still blowin cold. I did what you said about checking the hoses and if your looking on your engine bay the left hose is hot, and the right one is luke warm (not as hot as the other). Now what do i do?

 

Yep..your heater core is plugged up. Try back-flushing it....disconnect both hoses from the heater core (at the firewall) and hook a garden hose up to the one on your right (looking at the firewall) flush it with somewhat low-pressure until you get nice clear water.

Oh yea....you need to get that coolant leak fixed.....that's why the core plugged up....dexcool starts turning to a solid when air is introduced to the cooling system. Check your water pump and intake manifold gaskets for a leak.

 

can i change from dex cool to regular *** coolant. i have heard alot of bad **** about this dexcool crap.

 

YES you can, according to Havoline (maker of Dexcool for GM) you can even mix the two types, but it will shorten the life of the Dexcool formula.

I flushed my heater core in late winter (Jan/Feb) this year and now it is plugged AGAIN I don't see any visible leaks and my oil and tranny fluids do not show any signs of coolant contamination. I replaced the cap at the same time i flushed my heater core just in case that was the problem. Also check your thermostat when my system was running cool I found that the T-stat was stuck open, not letting the system fully heat up properly, gauge showed 150* when fully warm (not good for everday driving, but sweet for drag racing). So I replaced with factory 195* T-stat, I am considering lowering that to a 180* for better performance and hopefully mileage too.

 

You might get better performance out of a 180. It will trick your computer into thinking its colder, which will make it run richer which will probably drop your mile 1-3 mpg, but help you with the ponies.

Brandon

 

MY HEATER WORKS AGAIN. THANK YOU FOR RUNNING ME THREW THE BACK WASH OF THE HEATER CORE. I LOVE YOU GUYS!!!

 

No problem! we love ya back!.....lol