SlowRidin03

and yes i searched before posting

have an 03 with the EATC. Finally got cold enough last night to ice the windshield over this morning. Turned defrost on and let it run for about 15 min before I went out to leave. Still had a frosted windshield

got to checking... On defrost, heat is coming 80% out of front vents, 20% out of defrost vents. So, started checking all of the settings. Any setting you put it on, it will coming out 80% vents, and little defrost vents, but nothing comes out on the floor (even on its setting).

Even after the system is turned off, it still slightly blows out of the vents (which gets hot if you dont close the vents!)


Researched on here, pulled the head unit off and noticed there is a post on the rear that looks like is missing a vacuum hose. I have black, white, red, blue and yellow-orange hoses firmly connected to the back of the unit, what goes on the missing post? There were no other hoses around.

Popped the hood and checked where it all goes into the firewall, and everything look plugged and fine, except a hard small black hose that is not connected to anything (but wrapped up in the same wire bundle as the rest of the vac. hoses)

Sorry for the long post, but can anyone tell me what hose I am missing on the back of the HU, and what the hard black hose goes to?


I also ran the diagnostic test and nothing came up, so I'm out of options here

Thanks in advance

MattB1969

I think it's a blower motor resistor that has gone bad or it's blend door actuator failure. anybody else have some input?

wde3477

The blower motor resistor should affect only the fan speed. It's failure is typically seen by not having the lower speeds, only the high speed function.

If you've got the electronic head unit, then I would assume that the temperature blend door is now actuated by a vacuum motor, where it is a cable-actuated feature on mine. At any rate, this should bring the total number of vacuum motors in the system to four - the panel/floor, the floor/defrost, the recirculation, and the temperature blend motors. Add one for the vacuum supply line, would expect to see a total of five vacuum lines at the head unit.

If I read your colors correctly - it appears you have the correct number of lines - (1) black, (2) white, (3) red, (4) blue and (5) yellow/orange. Not sure what the extra post you describe would be for.

It appears that none of the airflow dampers are working, since you can't get the airflow to change its outlet ports. Suggest to inspect the vacuum supply line between the head unit and its source in the engine compartment - black would be my first guess. Verify that it is sourced to vacuum, and that there are no leaks in the line. The loose line you found in the engine compartment is suspect - look for an open or a capped vacuum port within reach of this line's range.

I suppose it is a possibility that the head control unit has failed. Fixing vacuum lines are much cheaper than a head unit replacement, so recommend to verify all is good with the lines before going after the head unit.

Then, there is the possibility of one or more vacuum actuator failures or damper binding - this will be a laborious task to verify each one. The little hand-operated vacuum pumps available at Sears or most auto parts stores is a tremendous help for this type of troubleshooting - but will shell out about $50 for it.

Good luck, and keep us posted on what you find.

SlowRidin03

think you have nailed it... finally got in touch with a Ford tech and this is what he told me

So i followed the instruction, and it did not blow through the defrost still, so it appears to be a vacuum leak or door actuator problem somewhere. Hope to have some time this weekend to look into it and will report back