I have a 1999 Sierra with 5.3l and I have no heat at all. Temp guage looks normal runs around 210 degrees. Should I try flushing the heater core or do i have a problem with some sort of regulator?

 

How does ur coolant look? Do you change it at least twice a year? If its dirty then chances are the heater core could be clogged. Also I think there is a blend door that needs to open behind the glove compartment. Correct me if I am wrong.

 

coolant's never been changed - only topped off for thermostat changes and when low - I'll flush the core and check the blend door - just looking for someone else that had this problem as well - has gotten progressively worse over the past 6 months.

 

Heater core could be the problem. I had an Impala SS 1996, and a '98 CCLB Silverado that were bad about that. Good luck. Try flushing the core itself and see if you are getting good flow.

 

I have exactly the same problem. I removed both hoses at the firewall and flushed the heater core. No apparent problems or blockage. Engine temperature is normal, just no heat.

 

I'm going to change out the dexcool and flush the core while i do that - I suspect the blend door as I was getting some heat this past weekend (believe it or not I needed the heat in August).

 

Dang where you live at?

 

Minnesota - it's been a crap summer - maybe 5 days over 80 degrees - most nights down into the 40's, wind just blows 15-20 all the time.

 

My kinda weather!! Lol sorry but I love the cold! Here is West Texas its dry and hot. Usually around 105 on average. If ya want you can go in with the green stuff. Just as long as you dont mix with Dex Cool.