jgray152

I searched but couldn't find anything relating to my truck.

1998 Chevy Silverado K1500 6 Cylinder

I don't have any heat in my truck. One line going into the core is warm while the other is cold.

I was thinking it could be a clogged core but a mechanic told me that it could also be a heat core valve.

Where is the heater core valve and what do you think the problem probably is?

Previous symptoms leading to issue.
I noticed before this happened which was about 4 months ago, that the heat was not really hot and I could leave it on full blast all day long and it would just take the chill off inside the cabin. Now I also noticed when I was towing a horse trailer and reach a hill, the engine temp would climb a little and the heat would get very warm at that point and after the engine cools down during some straight stretches the heat would become just slightly warm. At first I thought maybe someone put in the wrong thermostat.

Now, the heat doesn't work at all. Although If I let the truck heat up and drive it for a while, turn the heat on I feel a very quick sensation of slightly warm heat for a split second then its cold.