F750 HVAC

[funwithfuel]

My service truck is giving me fits. She's a 2012 F750. Early in the day A/C blows fair and cold. As the day goes on air flow chokes off, fan still trying. Then sometimes the air acts like it just flipped off, air flow chokes off and gets hot. Compressor is pumping, pressure is good, lines are hot and cold. Anyone got any idea? I don't have any schematics or descriptions on who does what.

 

[Coaldust]

The blend door actuators are a known issue with those rigs. They can act erratic vs totally failing. The linear motor chip goes bad in them. Something to consider.

 

[funwithfuel]

So, would that be the actuator or the controller? Like i said, i have no supporting materials and thanks for the info

 

[heymccall]

The loss of air flow indicates evaporator freeze over. The evaporator temperature sensor is suspect.
This video gives a gist of what and where, but, on this one it's reading low. Yours is likely reading high.
If you read the comments, one put a hole on the box and was able to change it without the 10 Ford hours labor.

 

[Birken Vogt]

You can confirm if it is a freeze up by intermittently switching the compressor off throughout the day and leaving the blower run. The air flow will stay good but get warm. It may leave a big puddle on the ground when the ice melts off.

 

[funwithfuel]

I had speculated the possibility of freezing, the evaporator never stops dripping. And if i shut it off, it stops dripping after a minute or two.
Are these doors controlled by a BCM or something like that

 

[heymccall]

There is no door that will stop airflow.
Save some aggravation, and guessing, and get a scanner, like in the video, on there.

 

[funwithfuel]

My son will have to do that for me. Appreciate the input

 

[mg2361]

My son will have to do that for me.

You could get Forscan for free and the adapter fairly cheaply. I did years ago and it works great.

http://blog.obdii365.com/2020/05/13/download-install-and-activate-license-of-forscan/

https://www.amazon.com/Forscan-Scan...ocphy=9007201&hvtargid=pla-637551798938&psc=1

 

[funwithfuel]

Now that looks like fun. Thanks.

 

[heymccall]

Any luck?

 

[funwithfuel]

No, haven't had time. Too many projects demanding my time. Cooler weather is around the corner