Heater Control Valve vacuum connections

[wn007]

I am new to this forum. I have a 2003 Expedition 4.6 and after rebuilding the engine I have a vacuum line that is no longer attached coming from the heater control valve. Would like to know where it terminates. I think it goes through the firewall but really am struggling to figure out where. I have seen a few vacuum diagrams but they lead me no where. The only mode that works is the Defrost. The blend door seems ok since I can control the temp no problem.





2003 XLT 4.6

 

[Bedrck47]

Welcome to the forum

 

[wn007]

Thanks! Hopefully I will be able to contribute as well. First time owning an Expedition.

 

[Bedrck47]

do you have manual control or electronic control for the heat/ac

 

[Bedrck47]

Vacuum Schematic — Manual A/C
Item Part Number Description 1 18A318 Vacuum control motor — floor/defrost door
2 — Defrost air flow
3 18A478 Floor/defrost door
4 18476 Heater core
5 19860 Evaporator core
6 19805 Blower motor
7 — Outside air inlet
8 19A813 Air inlet door
9 18A318 Vacuum control motor — air inlet door
10 — Recirculated air inlet
11 18B545 Temperature blend door
12 18A559 Panel door
13 — Panel air flow
14 18A318 Vacuum control motor — panel door
15 — Floor air flow
16 — Vacuum from the engine intake manifold
17 19A563 A/C vacuum check valve
18 19A566 Vacuum reservoir tank and bracket
19 19A563 A/C vacuum check valve
20 19B888 Function selector switch
21 18495 Heater control valve

 

[wn007]

I have manual climate control. Thanks for the diagram. I did figure out how to get the controls to cycle the vents. I attached a black vacuum line that comes from the manifold through the firewall just behind the battery and everything works. The only one I cannot figure out is the heater control valve. Also, I don't have cold A/C which could be a whole different issue.

 

[Bedrck47]

Port Hose Color Function
1 White Air Inlet Door
2 Blue Floor/Defrost Door
3 Black Vacuum Source
4 Yellow Floor/Defrost Door
5 Red Panel Door
6 Orange Panel Door


Vacuum Application Chart — Manual A/C
Switch Port Color Function Function Selector Switch Position
MAX A/C PANEL PNL/ FLR OFF FLOOR FLR/ DEF DEF
1 White Recirc/ Fresh V NV NV V NV NV NV
2 Blue Floor/ Defrost NV V V NV V V NV
3 Black Vacuum Source V V V V V V V
4 Yellow Floor/ Defrost NV V V NV V NV NV
5 Red Panel V V V NV NV NV NV
6 Orange Panel V V NV NV NV NV NV

V = Vacuum


sending you a PM

 

[wn007]

Thanks! At the moment everything is working. I connected the white vacuum line from the heater control valve to the other port at the firewall. Once we added some refrigerant the A/C started working. I have noticed that the temp control is a bit flaky. It seems that either the blend door is sticking or the actual control knob is not operating properly. In other words it would blow hot air on the coldest setting but after rotating it fully a few times it worked ok.

 

[Pinky 1352]

This is a long shot that anyone still gets notifications for this thread, but if so, can anyone tell me where exactly the vacuum connection from the heater control valve GOES?

I have this same model it seems and can't figure things out.


BTW, thanks Bedrck47 for the diagrams as that has at least given me a clue as to how the whole system is "wired"