Recently, I had to change out the heater core because the old one was leaking. In the process, I also changed out blower motor and A/C evaporator (A/C wasn't working and I was going replace all the A/C components starting with the evaporator). After reassembling the dashboard, I checked the airflow, the floor ducts, demister and defroster ducts were fine. There was no airflow from the dash panel ducts. Should there be airflow at these panel ducts or since the A/C is inoperative at this time, there should not be airflow? Perhaps improper reassembly causing a blockage? Any thoughts on this matter would be appreciated.

 

Welcome to the forum Stan.

Airflow is controlled by vacuum operated doors in your '98. Make sure that all the lines are hooked up correctly and that the doors are free to move.

Whether the a/c is working or not doesn't affect the door operation.

 

Thanks for the reply. I might have been looking for a quick and easy solution. But, I had to pull out the old FSM and do my homework. If someone has a similar problem this might be helpful, I found that there are 3 vacuum actuators controlling the airflow.

One controls the air re-circulation door and is located to the to far right near the passenger side door. It's attached to the AC/heater housing. It's very visible with light green and dark green hoses connected to it.

The second controls the floor/defroster door and is located above the acceleration pedal. It's attached to the AC/heater housing. It's very visible with yellow and blue hoses connected to it.

And the third(which was the problem) controls the panel/defroster door and is located above the second actuator. It's not attached to the AC/heater housing. It's not very visible. It appears to be internal to the AC/heater housing with integral ports projecting from the housing. The red and brown hoses leading to it were not connected.

Also, I pulled the dashboard forward and let it rest on the roll down bracket slot in order to gain working space.

 

Appreciate the write up, copied and saved. If you can please post a short description in replacing the core as mine is clogged and will have to be replaced one day. I get very little heat but it's not needed much here in Florida. Thanks!

 

Have you tried flushing and back flushing the core yet?


https://dodgeforum.com/forum/2nd-gen...ore-flush.html

 

Try the flushing first. If you watched the Cooper Lake Automotive video, you can see that it's an ugly process. I have done it twice. I pull the dash forward just enough to be able to remove the AC/heater housing. You will need to disconnect AC lines from the evaporator. The second time I did it I removed the front seats to create work space. It's complicated with many electrical connections, vacuum hoses, screws and bolts. They all have to be marked for re-assembly. You can do it but, you need the time. If you rush, you will make mistakes.