Heater core issue

[fordysenior]

Hello, while driving the vehicle today, with 137k miles on it, I had the defroster on since it was raining, and everything was fine. When I took it off the defroster and put the heat on through the panel vents, I started getting the inside of windows fogged up -- which is unusual. I think it's time for a heater core replacement. If so, do I have to open up the a/c system, so I would need to get it discharged, and then recharged after the repair?? Also, do I need to remove the front seats? How about the steering wheel assembly? I guess I'm going to have to remove the dash, or at least pull it out of the way -- on my F150, I only had to swing out the right side of the dash. Is complete removal of the dash necessary? And while there, should I replace any other parts, such as blend doors or actuators -- all components are working fine except the actuator arm came off the fresh air door, the little tab the actuator arm goes on is still there, but I just shut the fresh air door and really don't care if it works. Any other hints appreciated, thanks. It's the original factory set up.

 

[mountaineer2004]

Big job. Yes, while it's open, I'd replace the actuators.

 

[Joe in NY]

Wait, it was raining an you put the vents to panel and the windows started fogging up.

-That is normal. The rain causes any humidity in the cabin to condense on the windows and thus "fog up." If you had it on defrost and the windshield was fogging up then that would suggest a leaking heater core, failed a/c, or recirculate is on.

Defrost:
-Outside Air
-Windshield vent or Windshield & Floor
-A/C on if above 35*

 

[fordysenior]

Hi Joe, here on the West Coast, we drive around all the time with the heat on and blowing out through the vents, but no moisture buildup on the inside. You east coasters seem to have more moisture and rust problems than those that live on the west coast. My thinking is that when I had it in the defrost mode, the a/c kicked on and controlled the moisture, but when it's going through the dash vents, the a/c is not on -- and typically there is no moisture buildup here. I did a pressure test on the cooling system and it slowly lost pressure -- I started at 14 lbs and it slowly went down.