Specs: 2001 Blazer LT 4X4, 4.3l v-6 with 147,427 miles.
All I am getting right now is luke warm air out of my vents. (BTW I have the Auto Climate Control System.) My engine does not overheat. It warms up and settles down just south of the 210 mark which is normal. It used to go past the 210 mark for a few minutes and then back off and I assume that is when the t-stat opened up. I replaced the t-stat and a little change but not substantial. Both heater hoses are hot to the touch when the engine is running. The upper radiator hose is hot as well but it does feel a little "spongy". I am not sure if I have an air lock or a plugged up heater core. I live in a townhouse development so any work would be limited to what I can get away with in my sparking space. Any advice/help would be greatly appreciated.

 

i would flush the cooling system

 

If you can run a garden hose to your parking spot, or if you have a buddy with a house with one, bring a 6-pack and tell him you need to use it. I'm all for the radiator flush vote and buy a new radiator cap while you're at it, seems like mine go bad after a few years and the system doesn't refill properly or lack of pressure release takes out the radiator or LIM gaskets. As to the garden hose..... Disconnect the heater hoses at the intake manifold and the top of the water pump and connect the garden hose to each heater hose and flush the core back and forth. If it starts out slow and then starts flowing better - that was your problem. If it's plugged the flush solution won't go thru either so I do this first when I have a heater problem. Wrap a rag around the hoses to cut down on you getting sprayed <G>. Oh, and do NOT try this with a high pressure hose at the quarter wash!

 

I would suggest you use the search feature of this forum and look into the blend door actuator. This is what mixes the hot air with the cool air at the dashboard. Seems to be somewhat of a common issue that I've seen in this forum. From what you describe, if both heater hoses are hot and the temp is normal, I would look into this first before flushing.

 

Checkto see if you have anti freeze in tha passenger floor board if so heater core is bad

 

Before you pull anything apart, you need to narrow down source of the issue. Check the temperature of the hoses that go into the firewall. If they are both about the same temperature, the core is flowing properly and the problem may be with the blend door (located behind the glove box on the top of the HVAC housing - basically right under the passenger side speaker).

If one hose is noticably cooler than the other, the core is likely restricted and is in need of flushing.

 

Both hoses seem to feel to be about the same temp. There is no antifreeze in the passenger floor board (thought about that first as well). So I guess when I get a break from this freaky weather I'll stick my head in the glove box and see what I can see. What tell-tell signs am I looking for if it is the blend door? Will it be stuck in a certain position or is it going be movable? Let me know and thanks for the input.

 

Typically the blend door actuator will click but sometimes it won't do anything at all and you really can't see it do it's thing unless you a hole in the HVAC housing.

If you have the manual climate control, the actuator isn't that expensive at ~$30. The one for the automatic climate control is not so cheap though at ~$90. Typically, the large gear inside the actuator breaks and then the shaft that drives it just spins.

 

I was wondering if a weak water pump would create the same issue?

 

Unlikely. From what you describe the cooling system is working properly (temp normal and heater hoses are both hot) Water pumps generally fail from a bad bearing or seal that will cause them to leak. Have you looked into the blend door yet?