ok. my question is i have a 93 z28 camaro and the heat doe not work. it blows cold as if the ac is on. i think i could here the ac compressor click or somethning even though the switch is turn to the red. i have change the themao stat. it still do the same thing. i touch the upper radiator hose and it is luke warm compare to the other hoses being to hot touch. i also noticed this car with a by pass hose on the heater return hose. do that make a difference. i used to have a 95 z28 an i never seen this by pass hose before. what is it for.

 

heater core........ my 95 does that too. F-it its stored winters lol...

 

Apparently you heater core was bypassed, so you will never get any heat. Probably the heater core was leaking.