It should be all new antifreeze when thermostat was changed. Going to flush the system this evening. just to be on the safe side.

 

hey, whats up freezing fire fighter,
I have the same problem that i am tring to figure out (2000 Chevy Silverado Ext. Cab 5.3l NO heat and the ac blows me out of the truck). Had aguy told me that he had a problem with the the vaccum hose was dry rot and leaking in his dash and that his check engine light came on and went off every now and then do to vaccum leak and that his gas milage was cut to 14-15 mpg.His fix was change the vaccum hose. so thats what im going to do this weekend, find thebad hose. but first im going to disconect the hoses and make shur that the core is not blocked.
Keepin touch.
frozzzen in SW LA.

 

Change your thermostat again

 

Flushed the radiator and the heater core last night. Got up this morning had heat within 5 min of starting truck. Drove 15 miles to work had to turn off heater it was driving me out of the truck. The antifreeze in the core was real thick. but tink the problem is solved. Now on to the transfer case and the A/C.

 

Thanks for all the help.

 

Life is good with heat.
Flushed my core out also lastnight and was punching the sky because thethought of getting into the trucks dash turned my stomach. Think Im going to keepit now.
LTZ's sweet but mine is paid for and now has heat again. SWEET!!!!!!!
Burned up by truck heater in SW LA.
Mine was also thick!

 

Hey I am having the same problem with my 98 silverado. It takes me about 15 minutes after it warms up. Also when I have the heat off it pumps out heat pretty good still heating up the truck. Kinda feels like it is seeping through the engine but the engine is not overheating. AC works beautifully though. MCFD625, did you have that same problem when the heat was off? Any help would be appreciated.

 

Hey guys i have a 1990 silverado with the good old 5.7 350 and im having somewhat the same problem, the truck wont put out any hot air and i only get luke warm air about 45 minutes of constant driving AFTER i let the truck "warm up". Only difference with my situation is that my oil also looks like its getting some thick greyish gunk in it and i just had it changed?!?!?! The temp gauge in the dash reads normal but it fluctuates when it feels like it and im thinking what the hell is going on here??? I checked the antifreeze and its still full, and i also just had it changed..... Im not completly ignorant when it comes to stuff like this, but this one's got me stumped...... Any help would be appreciated..... thanks..... soldotnadude