Heater is blowing cold air

1998 CHEVROLET CORVETTE
90,000 MILES
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RONNIERAY01
  • MEMBER
  • 1 POST
Blows air fine but does not get warm.
Nov 22, 2017 at 2:21 PM
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JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
Check the following:

Is coolant level full?
Is engine warming up to normal operating temperature?
If the two aforementioned items are good, allow engine to warm up with heater on. Feel both heater core hoses. Are both hot? If so, suspect a defective blend air door. If only one heater hose is hot, suspect a plugged heater core.
Nov 22, 2017 at 4:48 PM
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PATENTED_REPAIR_PRO
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 1,853 POSTS
This may also have a heater control valve located on either heater hose. If so, check the heater hose just before and just after this heater control valve, both hoses should be hot. If the hose going into that valve is hot but the heater hose coming out is warm or cool, then look to see why that valve is not opening, maybe a vacuum hose fell off of it, etc., of the valve is simply stuck.
Nov 23, 2017 at 8:17 AM