Hey everyone. Found this site cause I was trying to figure out what's going on as to why no heat. But need more help.

2001 Blazer 4.3 4wd automatic.

Got the truck non running. Bad engine. So put another known good 4.3 in it. Runs very well.

Issue no heat. Has the auto climate controls.
I've tried these things.
Flush heater core with water some grud came out not to much, but gloes water.
Replaced radiator with a spare I had old was pretty clogged up it seemed.
new water pump
Tried 2 thermostats.
Tried jacking passenger side up to "bleed" the system.
Ran it idle with and without the cap. Cap is good. Even drove it to town.
Overflow has fluid
Will sit and run at like 205°

Lower radiator is hose cold.
Upper radiator hose warm not hot and soft.
Heater core hoses both same temp. Soft.
Thermastat steel water neck hot.
I just got done messing with it. Ran half hour idle and I took cap off no pressure at all. And I can stick my finger in the radiator fluid and it's warm not hot.

A/C doesn't work. Not sure why. Button lights up but I assume it's cold outside so it won't engage.
Blower motor works and the door that selects vent dash, floor, mix, defrost all work. The temp dial unsure of as I can't hear anything change when I turn the dial.

I'm lost not sure what's going on. Any ideas will be greatly appreciated.

Thanks.

 

That you cooling system is not appatently getting hot does imply that the cause of your lack of heat is with it. However, it appears you addressed all of the issues with the cooling system I can think to try.

A Failure mechanism that I didn't see on your list is the blend door actuator. You might look into that to at least eliminate it as a cause.

 

Would thay blend door cause the cold lower hose and no pressure in the system?

 

Can you go into exact details on how you burped the system? I find it best to raise the whole front of the truck on car ramps. But it would be good to know everything you did to burp it.

 

No it would only affect the temperature of the air delivered by the HVAC system.

I thought both heater hoses were warm? I must have missed that symptom.
Edit: you reported the lower radiator hose was cold. Odd.

 

Here are a couple more thoughts:

• Did you flush the new motor cooling system before installing it? Could there be crud in it that got loose and blocked the replacement radiator?
• Is the water pump working properly? Can you tell if coolant is circulating through the whole cooling system? The cold lower radiator hose is crazy odd.
• Are yoy confident the replacement radiator was fine?

 

Drove the passanger side up on a cat ramp and ran it with and witout a radiator cap to bleed it.

 

I didn't flush the new motor. Never thought about it actually.

The water pump is new. But doesn't mean it's good lol. I can barely see circulation in the radiator now that I think about it. Fluid level in radiator does slightly go up and down in radiator while running.

The new radiator im fairly confindent is good. I flushed it before installing it.

 

You say that both heater hoses are same temp but you don't say what that temp is. When you flushed the heater core did you flush it reverse of flow? And what does 'gloes water' mean? I suspect it's a typo but I can't cypher it out. Can you see water flow in the radiator when you first start the engine? Is the thermostat in correctly?

 

I dont know whatt temp. Just used my hand.

I flushed reverse then normal when I did the core. I might bypass the core today to see if it solves the lower rad hose being cold.

When running and cap off the fluid moves but not much.

Thermastat is installed with spring facing down.


My typo *gloes water* is to be flows water.