This is for my wife's car, 97 Lumina LS 3.1L. This has the dual zone HVAC.

I just replaced the evaporator core and heater core. Now, I only get heat out of the passenger side. On the driver's side, when I go from cold to hot, I get reduced air flow and cool air. I also checked, and all vacuum and electric actuators are working smoothly.

So I am fairly confused. My next step is to take it all apart again and see what could have happened.

Anyone run into this?

 

Bump, 100+ views. No one has seen this?

I went out and checked again. All actuators seem to be moving as they should. I tried pulling the HVAC fuse and will see if that "reset" anything in there.

Then after that, I am thinking of pulling the radio and looking at everything up top.

Is there a chance I got a defective heater core that is only warm on one side? It felt warm all around the box in that area when the car was running.

 

sounds like an air distribution problem.

the heater core air is split by different temp blend doors not by running air through different halves of the heater core.

what was the orginal problem? why was the heater core replaced?

 

I replaced the evaporator core because it was leaking freon. I replaced the heater core because of the labor involved and age of the car and it had never been replaced before. I wanted to do a pre-emptive repair on that one.

All the distribution doors are moving just fine. I am thinking I could have an air pocket in the core, which could be causing the issue. I now noticed that it has a little warm air on the driver's side having tried running it through a few hot/cold cycles.

I am going to try jacking up the corner of the car and see if I can "burp" the air out.

 

air in the system typically shows up as less heat at idle and more heat at 2000rpm; as more coolant circulates through the heater core when the water pump spins faster.

 

Okay, got 'er figured out. Turns out, the mechanic did not seat the heater core all the way. I am not even sure how I got it all together and seated wrong, but I did.

As a friend I talked to locally told me, it's a mistake I will remember and likely will not make again.

Thanks for the help here, guys!