Now that it has gotten quite cold, I've discovered that my heater doesn't work very well. I bought the Blazer in July, so I'm not sure what to expect for the heater. How hot do Blazer heaters get? In my car, the heater gets so hot that I can barely stand to hold my hand in front of the vents when it's on low. However on my Blazer, when on setting 2, it's mildly warm, but never really heats up the cab on a cold day. If I crank it up to 4, the air coming out of the vents is barely warm at all. Do your heaters get hotter than this?

If this is a problem, what do you suggest? The engine temperature gauge shows that the engine is up to expected temperature. Oh, and the A/C works great in the summer; it's just the heater that doesn't get very hot.

Thanks for your advice!!

 

I would say that your heater core has a restriction of some sort in it or the inlet/outlet hoses. Anything that restricts the flow of fluid through the core will cause a poor heat output. I would suggest flushing your heater core when you get some time. Disconnect both of the hoses where they meet the intake manifold and the waterpump. Then, using a garden hose, flush through both of the hoses until the water runs clear.

Be aware that this may loosen debris inside your core that has been there for quite sometime. It is not unheard of that flushing a clogged core leads to heater core failure (leaking inside the vehicle). If this happens, you must replace the core. Heater core replacement is a daunting task for the general shade tree mechanic, but we can walk you through that if it comes down to it.

 

yep! my mom just got hers flushed on her 93 fifth ave. it was almost a night and day difference. kyle, why cant they clean the core out.....?

 

You definitely can clean the core out, I'm just warning that there is a possibility that, in the process of cleaning the core, you may open up leaks in the core.

 

Thanks for the input. I got my engine cooling system flushed last week (and they of course didn't even refill the coolent system halfway), but maybe it's time to flush the heater core now. I had never thought of that being an issue. Blazinloud - when your mom got hers flushed, did it heat a lot better, or what was the world of difference?

Normally I'd just do something like this myself, but I now live at an apartment complex where they frown upon doing this type of thing.... Will most places that flush radiators also do the heater cores, or should I take it to the dealer? I really wish I could just do it out in the parking lot...

Any other ideas of what it could be? Is there a thermostat that controls the coolent being pumped through the heater core? Or maybe the vacuum valve controlled by the temperature **** might not be working right?

Thanks!

 

Problem is going to be someplace that is going to actually try the flush before telling you that you need to replace the core.

Anyway, no, there isn't any valve or tstat just for the heater core. Coolant is continuously running through the core. It is the air that is directed through the core in varying amounts to get the air temp to the proper level.

If you were to flush the core and that did not correct the problem, then you may have a mode door actuator problem. It is located on the top of the HVAC housing and can be felt by pulling down your glovebox. I would think that your mode door is working properly if your A/C is cold and you then get some heat... But, like I said, it would be the next thing on the list of things to check if the previously mentioned heater core flush did not completely remedy the problem.

Good luck!

 

Ok, thanks for the advice. In the next few weeks I'll try flushing it, and let you know what the outcome is.

 

Interesting, I have a very similar problem, went back home to Tennessee for the weekend and it was nice a cool up there compared to the heat here in South Florida, well, my blazer seems to be stuck in Florida mode as only the air blows cold. Wow, what a trip, I can turn the temp *** all the way to hot, and the only thing it really does is tries to divert the air away from the dash vents to suppress the cold air. Needless to say, even if the A/C is not on it is quite cold in there when the outside temp is less than 50 degrees. The best thing I could do in the moment is turn the fan off.

Anyone have any ideas on this? I first suspected the head control unit, but after reading the previous posts I consider that it might be something else. Suggestions please.

 

Ok so you are looking or suggestions beyond what's been laid out here already??? Have you attempted to flush your heater core?

 

Sorry, should have clarified: I have not flushed the heater core, that is the next thing to try, but I should have asked if anyone thinks it might have anything to do with the head unit, as that matter was not brought up.