AZ2NV

I have a 1994 Z28, and the heater does not work. The blower motor blows fine, and the switch that operates the temperature still has tension on it so I don't think it is broken. I read in another post that the radiator cap could be the problem so I'll swap caps between my ls1 and the lt1 tomorrow. I swapped the thermostat in the car because I was having cooling problems but it is a 180 degree unit. I work at Advance Auto parts and this was the only t-stat that was listed. I thought these cars should run around 210? I have also swapped all of the cooling fan relays, and both temperature sensors, the one under the water pump and in the cylinder head. I have my running hot problem solved but I fear that I created my no heat problem. Sorry for the long post, but any help would be greatly appreciated.

TraceZ

I would not recommend switching radiator caps from the lt1 car to the ls1 car. You will allow air to get into the system of the LS1 car, and the cap might be for a different pressure.

The LT1 car could have air in the system, or the core could be plugged up. Try removing the heater hoses from the water pump and engine, hook your garden hose up to one and let it blow out the dirty fluid from the heater core. Put it back together, bleed the air from the system and the core should get nice and hot next time you run the car.

AZ2NV

The entire cooling system was recently flushed by one of my friends who is a GM master certified tech. The cooling system was vacuumed out and then the new coolant was put in to eliminate air pockets in the system. I don't think the core is clogged up. I checked the radiator caps and both are for 18 lbs, so I should be fine. Any other suggestions?

TraceZ

If the heater core is cold, it has to be either plugged, the thermostat is bad, or it has lots of air in it.

Are you sure you put in the right thermostat? I've heard of parts books listing the wrong one for our cars. The LT1 does not use a standard SBC style thermostat. The bottom part of the valve is much different. Did you visually compare the new one to the old one? Did they look the same?

Bottom line is this: If the thermostat is working properly and the heater core is cold, there is either lots of air in the system, or the core is plugged up.

Did you friend pressure flush the core specifically? If he just drained it and refilled it, that would not help. You'll need to hook your garden hose up to the heater hose and let it blow it out hard. The amount of crap that comes out can be amazing.

And lastly, are you sure the hater core is cold? It could be that the core is hot, but the flapper doors in the dash are not working properly to duct the hot air into the car. In any event, I would start by power flushing the heater core.

SixSpeedShifter

I have similar problems. Any good How-To's on the core flush?

ShelbyZ28

My heat didn't work all last winter. This summer I had my whole cooling system flushed at my local chevy dealership and they did it the same way your friend did yours. My heat still did not work. I Finally got tired of no heat and decided I couldn't go another winter like this. I flushed my heater core last weekend and now I have awesome heat. Dang its nice lol . Use the procedure in this link. It only takes 20 min or so and if it doesn't work all you are out is half a gallon of coolant and some time. Plus you can cross that off your list of possible things that are wrong and move on. But I would almost bet its your problem.

http://web.camaross.com/forums/showt...hreadid=191218


-Bryan

AZ2NV

I had the heater core flushed and now the heater is awesome. When it was flushed, chunks of dex-crap came out of there. Now it has the green antifreeze in it so hopefully it won't happen again. Just having to take it to be fixed on the coldest morning of the year wasn't that fun