Anticipated Heater Core Temp Drop during high heat load (2025 XL with 2.3)?

[LSaupe]

Hi All: Have a cabin heat issue. It seem like a water side issue to me. Bottom line, when asking for a high heat load (I have a 2025 XL with 2.3 and manual temp control) (i.e. by placing the temp knob at max and the fan at full) my outlet cabin air temp falls to ambient as well as by heater core outlet water temp.

I am not sure what the specs are for this. I was anticipating maybe a 15F drop across the coolant side of the heater core and I have over 100F.

My assumption is the heater core should be able to deliver a high air temp even at high fan settings and the coolant remain hot throughout the exchanger.

Anyone know:

1. Max allowable coolant temp drop across the heater core?
2. If there is some sort of feedback coolant flow control to the heater core or does this run free (unobstructed) all the time?

Initially I would say it presents as a coolant flow obstruction, but... want to make sure there isn't anything unique with the Ranger and 2.3 that might be skewing things a bit.

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[LSaupe]

Anyone know of a source to see the coolant side (heater core) schematic?

 

[superj]

no but you should be able to just feel them once the truck has run for a bit to see which is warmer. then we can compare to mine or someone else's temps. i have a temp gun the garage.

mine is the older 2.3 though i don't think the heater system would have been changed

 

[LSaupe]

I can, I have about a 100F drop on my heater lines. Just trying to determine how a good one should be performing (i.e. one that has proper flow).

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