Heater Hose Routing for 5.0L
Reversing the heater core hoses ( 8 ) AT THE HEATER CORE will not cause any problems, and may help remove debris from the heater core.
To bypass a leaking heater core, disconnect the supply (lower, hot) hose at the engine and the outlet (with T) at the heater core. Loop the hose still attached to the engine back to the open nipple. Set the remaining hose out of the way.

1 Existing Screw (Part of Cowl Panel)
2 A/C Manifold and Tube 19D734
3 Wiring Assembly 9D930
4 Bolt Manifold to Compressor (1 Req'd) N805334-S2
5 Compressor and Clutch Assembly 19D629
6 Heated Throttle Body System (Part of 9E926)
7 Clamp 390761-S100
8 Hose (2 Req'd) 381260-S320A
9 A/C Evaporator Housing 19850
10 Wiring Assembly 18A586
11 Clip (2 Req'd) 19N704
12 Tag A/C Service Instructions (Part of Suction Accumulator/Drier)
13 Condenser to Evaporator Tube 19835
14 Hose Clamp (2 Req'd) 376240-S100
15 Hose and Tube Assembly 8548 (F2TZ-8555-B)
16 Existing Screw (Part of 8146)
17 Fan Shroud 8146
18 U-Nuts (Part of 8146)
19 Radiator 8005

The hard tube bolted to the alternator is this for E4OD trucks. The version for other transmissions (with the small nipple for the throttle heat return) has not been available for years.

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For more info, read this article.


Heater core installation:
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Owner caption May 2007 · Photo 1573 of 5000