Are Lumina heaters known for poor peformance?

I have a 93 Lumina with a 3.1 V6. I've had the car for two winters and the heater has never worked well. I've changed several thermostats, a water pump and 2 heater cores. The first core was bought from a parts house and it made matters worse, and the second was bought and installed by a Chevy dealer. The new core from the dealer helped some, but it still blows warm air instead of hot like my van. Is this a Lumina shortcoming or is there hope of getting some heat next winter? Thanks in advance

Rod

I have a 92 with 3.1 and you could cook on the defroster after about 10min and I live in Canada so cold winters are natural thing here. It sounds to me like you have an air lock in the system, these 3.1 had a terrible porblem with air locks, you have to make sure you bleed the system very carefuly, just using the bleed valves isn't alway enough. I know my mech. hate when I bring it in for any work that involves draining the water. Good luck, sorry I couldn't be more help.

Besides what is stated above, you need to make sure the damper doors in the heater asembly are moving to the 'hot' position. Doesn't matter if you have the hottest heater core in the world if the temperature damper is mixing cold air into the output.