Heater

1994 CHEVROLET 1500
15 MILES • 7.5L • V8 • 4WD • AUTOMATIC
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PODLE88
  • MEMBER
  • 1 POST
i replace the thermostat, and ran coolant through it. temperature gauge will go up to 200 and then back down to 150, while your driving. turn the heat on low, it works, turn it on high or med, it blows kind of hot then go cold. need help.
Dec 27, 2017 at 9:31 PM
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STEVE W.
  • ✓ASE Certified Mechanic
  • 15,200 POSTS
  • ASE Certified Mechanic
What was the temperature rating of the thermostat you installed? Was it doing this before the new thermostat?
First thing would be to verify the coolant level. Low coolant can cause the low heat. Next would be to test the new thermostat to verify it is actually operating at the correct temperature. I have seen thermostats rated to open at 195 that actually opened at 160.
Dec 29, 2017 at 8:32 PM
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