Lets start w/ the basics. I have a 97 blazer. Lately when I start the truck as I'm leaving the driveway I hear some gurgling behind the dash or firewall. I wasn't sure what it was but I was guessing a sign of bad things ahead. Now this morning when I went to turn on the heat it was blowing, but it wasn't coming out the vent it was supposed to. So I was think vacuum line? Then I put my hand over the defrost vent and the air was cold. My temp gauge then shot up over the two ten mark. Then it finally came down. So I was thinking stuck thermostat. Then I proceeded to watch it bounce up and down for the next 10 minutes. So after driving the remaining 20 minutes to work I try turning it on again there was a hint of warm to the air and it was kind of coming out the face vents.

Does a faulty heater core explain all this or should I be investigating something else. Thanks for your help in advance.

 

Check your coolant level in the radiator, it's probably low.
If it is, check for leaks around the bottom of the water pump.
keep us posted as to what you find or what step is next

 

*nods* air bubble

did you find a leak / low coolant level?