96 Ford Explorer No heat, Not Blend Door

[96GreenMachine]

Hey There,

I have a 96 Ford Explorer 5.0 AWD which currently has no heat. I replaced the blend door last year and can confirm it's still working. I can move from cold to hot and get different temperatures just never hotter than cabin temp on the hot side but super cold on the cold side. A/C works fine.

I do have a code P0141 O2 Sensor Heater Circuit Malfunction

... How do i fix it?

Read more at: OBD-II Trouble Code: P0141 Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor2)
Copyright OBD-Codes.com

 

[J_C]

P0141 is for your bank 1, downstream O2 sensor. It is not related to your HVAC issue but you could try replacing it.

Do the hoses to your heater core seem to be pressurized and heating up after a few minutes running? You could have the valve at the engine stuck shut or have a heater core blockage. I don't recall if the valve is normally open or closed when there is absence of vacuum, you could check for a vac leak at the vac hose to it.


You could take the hose between the two off to see if coolant is flowing out with engine running (when HVAC is set to hot) and likewise (but with engine off) take the return hose off and see if you can blow low-PSI compressed air through it, though another sign it is blocked could be that one hose gets hot but the return hose does not, of course after the engine has ran a "few" minutes to heat the coolant, then after a few more you'll get a coolant temperature dip as the thermostat opens up.

 

[410Fortune]

If the fan is blowing and there is no heat then you need to do like @J C said and test the heater core coolant flow:

really those are the only two parts of the heater, you already confirmed the bled door is blending...so
The heater cores on these trucks can get blockage inside of them, the fix for that is a backflush
The heater control valve can get stuck and warm coolant will bypass the heater core all together
The heater box can get full of leaves and debris blocking airflow from the fan

Those are the 3 things to check

 

[rasouth]

It also maybe possible that your thermostat is stuck open, not allowing your coolant to warm up properly. Your AC would still work normally no matter what your coolant temp was.

 

[96GreenMachine]

Thanks All, I'll be checking these things today. I ordered the o2 sensor to clear the code...happens to be the one in the hardest place. Annoying but doable. I'm moving cross country to Louisville, KY and while no heat was inconvenient in Mesa, AZ it's a no go where I'm heading. I'm tough and all but no windshield defroster is going to be an issue.

So I'll work through your suggestions and hopefully find the fix quickly. I drive it out there first week of December.