ac help

[BIG GREEN FORD]

On my 99 5.4 xlt expy the ac blows from both defrost and air vents its like if it was stuck between the two, also I have to start the car with the ac on the ac position if not the ac will get stuck on the defrost vents with ac. Any help? Can I stop it from coming from defrost at least. It gets real hard to see with the windshield foged up. Thanks

 

[stamp11127]

Check the vacuum motors/actuators, mode selector switch and source vac line.
You may have a stuck actuator or low vacuum.

 

[BIG GREEN FORD]

How can I check to see if I have low vacuum, or the actuator getting stuck?

 

[stamp11127]

Check the vac line from the engine to the mode switch. I think there is a line near the battery that has been problematic for others. Also listen for a low hissing sound under the dash. I'll look later for the location of the actuators so that you can test with a mighty vac.

 

[BIG GREEN FORD]

Thanks stamp

 

[stamp11127]

This may help.

 

[Bedrck47]

Item Part Number Description
1 18A318 Vacuum Control motor — panel/defrost door
2 18A478 Panel/Defrost door (full vacuum position)
3 — Defrost airflow
4 — Side window demister airflow
5 18B545 Temperature blend door (full heat position)
6 19860 A/C evaporator core
7 19A813 Air inlet duct door (full vacuum position)
8 — Outside air inlet
9 18A318 Vacuum control motor — air inlet duct door
10 — Recirculated air inlet
11 19805 Blower motor
12 — Vacuum to emission control
13 — Vacuum from the engine intake manifold
14 19A563 A/C vacuum check valve
15 19A566 A/C vacuum reservoir tank and bracket
16 19B888 A/C-heater function selector switch
17 18476 Heater core
18 18A559 Floor/panel door (full vacuum position)
19 — Floor airflow
20 18A318 Vacuum control motor — floor/panel door
21 — Panel vent airflow

 

[Bedrck47]

Port Hose Color Function
1 White Air inlet duct door
2 Yellow Floor/panel door
3 Black Vacuum source
4 — Not used
5 Blue Floor/panel door
6 Red Panel/defrost door

 

[thewishkah]

When the knob is on floor should air be only coming out on the feet or from the defroster as well? I noticed that when switching to panel only it works fine but from floor only to floor/defrost it doesnt change at all. If this isn't normal what color vac line am I looking for as the culprit? Thanks in advance.