Replacing Heater Core

Where exactly is the heater core in a 94 Z28? Will I have to pull the dash in order to get to it? Its blowing nothing but cold air.

before you decide to do that, make sure the vents are working proporly. when a heater core goes bad, you normally get a big green puddle on the passenger side floorboards. Id say much more likely that your heater door isnt working which would be a bad AC control head, or a bad actuator on the door itself.

but to answer the question the heater core should be on the passenger side firewall under the dash, and yes, youll have to remove the entire dash assembly to get to it. its not a fun project.

my advice is that unless you smell coolant, or there is a big puddle of it on the passenger side of the car, dont swap it out, and focus on diagnosing a bad AC control system part.

I just went through this a couple days ago on my 94 Z28. I will try to explain it all. First you should check to make sure that there isn't any air in the coolant line. There is a bleed valve just above the thermostat. So with the engine running at normal temp. turn that screw until radiator water is coming out, then retighten it. Then repeat the process for the second bleed valve just above and a few inches to the to left(when looking at the engine from the front of the car) of the first valve. A air bubble in that second smaller line will allow the car to run fine, but the fluid wont circulate through the heater core. If that doesn't fix it. You should next remove the cover covering the heater core to check and see if the air is being properly directed to pass through the core when you turn the temp. dial. To remove the cover you have to remove the 3 screws holding the bottom of the glove box in place and then push in on the sides of the box and pull the whole thing down and out. Then you have to remove the panel below that area. It is held in place by maybe(I don't remember) one screw and a metal clip holding the lower left corner of the plate over a metal post. Once that is done, you can get to the heater core cover. It is that large black cover directly visable through the glove box hole. Remove the two screws on the left side of the cover and then (with a little work) you can pull it out and down from behind the glove box hole. Now the heater core should be exposed. Just turn the temp. dial from cold to hot and back while running the fan on full and hold your hand next to the core, and see if the air is being directed properly. The only thing I know to do next is to remove the core. You have to drain the coolant system. Then remove the two hoses (held on with ring clamps) from the heater core that are tucked up under the firewall in the engine compartment, then remove the one screw and little metal plate holding the metal pipe ends of the heater core in the same place as the two hoses. Back inside the car, remove the one screw and metal plate holding the core tight against the firewall area. Then slowly work the whole thing down and out. I went through the whole thing just to find out that it was simply the air bubble in that smaller coolant line. I hope this helps.

Eric, what up man!!!!! How you doing? Haven't seen you on here in a while. Sorry invading your thread, poormillionaire2.

i didnt read that long ass post... but i just wanted to say that you should check your thermostat too. if it's stuck open that would be why you are getting cold air. heater cores rarely just go bad like that. i would check thermo and coolant level first. also if the temp gauge doesn't get to atleast 190 degrees it's definetly the thermostat. (assuming you haven't modified anything in the cooling system)

I don't have any puddles of coolant on the floor, so that's good and I just had my radiator flushed by my mechanic, so I don't think there are any bubbles that need to be bled. I don't think its my thermostat because the car reached normal operating temps just fine. But I might check it just to make sure. I was freezing my ass off driving to school in this 18 degree weather. I need to get this fixed fast. Thanks for all your input guys.

Do 4th gens have all the vacuum crap that third gens do? On my third gen there is a vacuum controlled heater switch located in the engine bay. Like RS said your ac control unit. Are all the vent doors vacuum controled? Check for leaks.

btw like link said to 89rs....whats up guy??

btw like link said to 89rs....whats up guy??

Yeah, no joke. I feel honored that 89Iroc has posted in my stupid thread. Good to hear from you again. Thanks for your help.


I still need to find time to check out my AC stuff out. Hopefully I will do it tomorrow when I replace my headlight. (It just went out tonight. ha)

im alive and well, ssdd ya know? had some spare time to i figured id swing by. oh and the AC stuff can be a bitch, especially if its this cold out and you dont have a garage to mess around in, it might be worth taking to the dealership to have them figure it out. not suggesting you cant or shouldnt do it, just kinda weighing the pros and cons of freezing your ass off in uncomforateable positions.