went to church this morning in the truck. the weather was a little crisp and so I turned the temperature **** to hot. after several miles there was little heat. after many mile there was still little heat. I assume the problem to be the electronics controlling the temperature or the heater control valve itself. where would be the first place to start to diagnose and fix the problem?

 

Pop your hood and check your thermostat.

 

Engine temp is normal?
The Blend door may be stuck. I think they are still vaccum activated, but, this is something the others will have to help with.
Your truck is an '02?

 

engine temperature is normal and the truck is a 98.

where is the blend door located? in the engine well or under the dash?

 

still check coolant level engine can still run cool because of out side air

 

coolant level is normal, where it should be. also the previous own disconnect the chime (because he camped a lot and want silence at night). I can't find it to hook it back up. Where is it?

 

under the dash on the fuse panel. it is really easy to find, just have to get under the dash. No need to remove any panels or anything. It just plugs in.

 

the previous owner must have removed it because it isn't there. now I need to go to a salvage yard and find one. I need it because my kid will probably leave the lights on and kill the battery if not reminded.

 

I went over to my neighbor who has a 99 suburban and he showed me the location of the chime. mine is definitely gone. it may seem trivial to some but I want it back in but at a different tone.

 

Blend door is in the cab under the passenger side dash close to the center of the truck. Remove the gun box(glove box) and you should be able to see you air duct system. After that......Never had to go that far.