2000 suburban heater I not blowing hot air

[knilive2]

I have a 2000 suburban with a 1500 motor and 300000 miles. Last year I replace the water pump and the thermostat. The heater would blow warm but not hot . But only when I start to drive. Yesterday I decide to change thermostat again thinking the new one from last year was faulty. Now the heater only blows cold air . Can someone help. What's the problem

[j cAT]

Originally Posted by knilive2

I have a 2000 suburban with a 1500 motor and 300000 miles. Last year I replace the water pump and the thermostat. The heater would blow warm but not hot . But only when I start to drive. Yesterday I decide to change thermostat again thinking the new one from last year was faulty. Now the heater only blows cold air . Can someone help. What's the problem

start cold engine with the coolant cap off. run engine until it is at the operating temp 190 deg f. rev engine to 2ooorpm a few times. fill coolant to the full hot mark with 100% GM approved dexcool.

this is the air purge proccedure.

[1996ctnc]

With that many miles have you flushed the cooling system? I have gone as far as undoing the heater hoses and flushing the heater core both ways you would be surprised how nasty it is sometimes.

[Cusser]

Like jCAT, I also think your issue may be related to air in the coolant system, you need to purge out all the air. This is not so easy on modern vehicles as hoodlines have dropped (according to the mechanic on the radio I heard Saturday). Does the 2000 have a traditional radiator cap or must one fill through the reservoir like on my 2005?

[mishalah]

Originally Posted by knilive2

I have a 2000 suburban with a 1500 motor and 300000 miles. Last year I replace the water pump and the thermostat. The heater would blow warm but not hot . But only when I start to drive. Yesterday I decide to change thermostat again thinking the new one from last year was faulty. Now the heater only blows cold air . Can someone help. What's the problem

And the conclusion to this was WHAT???

[j cAT]

Originally Posted by mishalah

And the conclusion to this was WHAT???

why ? you asking this ???