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I get no heat from my heater, it blows cold air...I have replaced the theremosta

(2003 GMC Sonoma)
in Dayton, OH on November 11, 2015
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3 answers & 6 comments
Popular Answer
on November 11, 2015
After engine reaches normal operating temperature... Are BOTH heater hoses 'HOT' enough that you can't hold on to them??
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on November 11, 2015
I did drain the radiator. Also have put in Prestone Flush to attempt to clean in-case system has sludge,

Have not held but touch the radiator and is not getting hot. Even I put in a New Thermostat, could this be a cause maybe it was defective???
on November 11, 2015
You didn't answer my first question! .. Here's another...Does it have or did it have the original factory installed DexCool in radiator before you worked on it?
on November 11, 2015
I have been running it for one day since I worked on it. Don't know if the antifreeze in it was the original. Have owned it since 2005 if that helps
on November 11, 2015
Google > DexCool sludge .. I suspect restricted or blocked heater core but without **hands-on** testing.. Can't say for sure... Good luck, I hope I'm wrong.. for your sake!
on November 12, 2015
ugh Oh sounds like if the core is plugged it would be very costly....Thank you for your help
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on November 11, 2015
After engine reaches normal operating temperature... Are BOTH heater hoses 'HOT' enough that you can't hold on to them??
Sign in to reply
on November 11, 2015
I did drain the radiator. Also have put in Prestone Flush to attempt to clean in-case system has sludge,

Have not held but touch the radiator and is not getting hot. Even I put in a New Thermostat, could this be a cause maybe it was defective???
on November 11, 2015
You didn't answer my first question! .. Here's another...Does it have or did it have the original factory installed DexCool in radiator before you worked on it?
on November 11, 2015
I have been running it for one day since I worked on it. Don't know if the antifreeze in it was the original. Have owned it since 2005 if that helps
on November 11, 2015
Google > DexCool sludge .. I suspect restricted or blocked heater core but without **hands-on** testing.. Can't say for sure... Good luck, I hope I'm wrong.. for your sake!
on November 12, 2015
ugh Oh sounds like if the core is plugged it would be very costly....Thank you for your help
The system needs to be bled properly do this by removing the radiator cap ensuring good coolant level fire up the engine and turn the heater on max run like this for 20 to 30 minutes be careful as coolant will be hot and make sure to monitor engine temp as well.
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on November 14, 2015
I am having the same problem! I've put 3 thermostats in my 2002 Sonoma. It does have the factory DrexCool in it. Pushrods...what do I need to check next?
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on November 14, 2015
Hands-on testing!...
After engine reaches normal operating temperature... Are BOTH heater hoses 'HOT' enough that you can't hold on to them? .. Heater hoses that go to the heater.. Located back @ the firewall on passenger side... Will BOTH of them start to burn your hand if you attempt to grasp and hold on to them??

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