heating issue ongoing for the last year

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expo dude

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i have replaced the heater cores, blend door, thermostat, water pump

its a 99 expedition 5.4l with front and back heat but no heat lol

if i run the truck in the drive i have low heat coming out when driving i have heat for moments but soon blows cold. i have replaced everything minus the heater lines could i have a semi clogged heater line going to the system or the output clogged


both lines hot at the in and out to the front heater core almost to hot to touch

i am lost in this truck someone anyone could you help with my situation
 

stamp11127

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Sounds like the flow is restricted. There is a restriction built into one of the hoses which may be partially clogged.
 
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expo dude

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after spending the last few hours looking at the issue i have found low flow coming into the heater core and high flow coming out if the core per garden hose. went down to the local auto store picked up 4 feet of 3/4 inch hose and rebuilding the main line that brings the coolant in from the water pump. and for the time being not hooking up the rear heat just as a test. found high flow since the hose rebuild and high heat in the front core and great flow out using the water pump. cut open the old hose finding the restrictor 90% full of grime but the rest of the hoses looking great. going to keep the home made hoses in place and incorporate the rear heat soon
 
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