2001 Chevy Blazer heater issues

Tiny
JPMATC
  • MEMBER
  • 2001 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 82,000 MILES
Ok, So I'm going to try to describe my situation as best as I can for an "accurate" diagnosis. I have a 2001 blazer 4.3L and I'm having heat issues, which I hear are normal with these.

My problems started about 2 month's ago. I noticed that the hot air in the passenger compartment got cooler all of a sudden. I didn't think too much of it until it started to get really cold. I also noticed that the temp. Reading on the gauges was just shy of 210, maybe 180. I read that it's usually not the thermostat that causes this, but I decided to replace it anyway just in case. That worked for about 3 hrs. With the heat that I was used to. However, now were back to square 1. I've noticed that the only time I can get the same good heat is when I'm driving and even that is hit or miss. I've checked coolant levels, and checked to see if I was gettin the same flow of air through the vents. This is all normal. I had my radiator replaced in July and am wondering if this has anything to do with my current problem. I have also checked the heater core inlet and outlet hoses and I'm not exactly sure what I should be finding there. I'm thinking maybe my problem now is the core and that fact that it might be clogged. I also have not ruled out the possibility of air in the system, and I will be trying to run the system with the cap off to get rid of some of the air bubbles if they exist.

Am I even close.
Sunday, January 18th, 2009 AT 8:50 AM

3 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Looks good to me. As far as the heater hoses on a warmed up engine, I like for both to be hot. If there is a big difference, I suspect a clogged heater core or heater control valve where applicable. Can you tell if there is good flow through the heater core?
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Sunday, January 18th, 2009 AT 2:23 PM
Tiny
JPMATC
  • MEMBER
  • 2 POSTS
I just went out and tried another idea I had. I took off the radiator cap, and started the truck to see if there was possibly air in the system that might be constricting the flow of things. I was hoping to have it boil over and have the air escape through the opening but I couldn't even get it to boil over or release any kind of coolant. After that didn't work, I replaced the cap and went on the core hoses. One was kinda hot, while the other was warm at best, it's 24 degrees here so anything seems warm. I'm leaning more and more to a clogged core.

I have instructions on how to flush it, but I dont know if a garden hose has enough pressures or do I have to add a sprayer on the end?
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Sunday, January 18th, 2009 AT 3:40 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Yeah, that would probably work. Do you have a warm place to work? I don't know how much pressure you need, at least you could check flow.
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Sunday, January 18th, 2009 AT 3:54 PM

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