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

(2003 GMC Sonoma)

kilroy20 in Dayton, OH on November 11, 2015

3 answers & 6 comments

Popular Answer

pushrod on November 11, 2015

After engine reaches normal operating temperature... Are BOTH heater hoses 'HOT' enough that you can't hold on to them??

kilroy20 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???

pushrod 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?

kilroy20 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

pushrod 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!

kilroy20 on November 12, 2015

ugh Oh sounds like if the core is plugged it would be very costly....Thank you for your help

General Diagnosis

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pushrod on November 11, 2015

After engine reaches normal operating temperature... Are BOTH heater hoses 'HOT' enough that you can't hold on to them??

kilroy20 on November 11, 2015

pushrod 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?

kilroy20 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

pushrod 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!

kilroy20 on November 12, 2015

ugh Oh sounds like if the core is plugged it would be very costly....Thank you for your help

eagletransmi... of Eagle Transmission Repair on November 11, 2015

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.

Andres1971 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?

pushrod 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??

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

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