hiya all wonder if you can help i have a 1999 cevy Blazer the heater blows cold on hot setting, have checked the fuse in drivers area ok any help would be appriciated.

 

*Moved to '2nd Gen Tech'*

 

your heater hoses may be clogged

 

It might also be possible your heater door is stuck on the cold side not switching to warm side

 

It may be the heater hoses or the heater core itself is clogged. With the engine off and the heater temp on high/all the way to RED/ remove the two small heater hoses at the water pump. With low pressure water hose, flush first one way, the the other to flush the clogged lines out. If you use high pressure water, you could damage the htr core. The GM long life coolant Dex Cool often causes problems and sludges up when not changed often or mixed with the 'green' coolant.