Question about 1999 GMC Sonoma

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99 gmc sonoma heater only blows cold air.The inside gage reads150


sometimes when times when I turn the truck off for a short time and return minites latter.The gage reads slightly higher ,but air is still cold.
The heater hoses are warm also.

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Odds are your heater core isn't working or plugged. Check your passenger floorboard for water, and replace the heater core. If that doesn't fix it, get a coolant system flush.

Posted on Feb 12, 2009

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Change the thermostat

Posted on Jan 30, 2009

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