No heat, what am i missing???

We have a 1999 ford ranger 3.0L engine
2 wheel drive manual transmission.

We can't seem to get heat.
Here are the steps I've taken so far!

We have had no heat since last winter. It just stopped one day...

I have replaced the thermostat

I have replaced the water pump

I have replaced the heater control valve and it is in the open position

I have flushed the whole system

I have flushed the heater core separately using a garden hose and there was decent flow.

I have tested the blend door and it works. I was able to swivel the door with my hand when the actuator was removed.

I have tested blend door actuator and i can c it moving and took it apart and the gears are not stripped

Heater control is working as it moves the actuator when the switch is turned

The rop rad hose gets nice and hot i can hardly touch it. What the heck is the problem?? I have run out of ideas???????

 

What do the heater hoses at the firewall feel like.
There is an IN and an OUT
In should be HOT
OUT should be HOT as well if heat in side is set to COLD and fan is off

Turn heat to HOT and fan to high, OUT hose should cool down quite a bit, if not then heater core is plugged down inside it, flow is OK thru the top but not in the middle or lower end of core

You can REVERSE the heater hoses at the firewall, this will Back Flush the heater core and maybe get some flow back, and this should be done each time you change coolant, it will make core last longer

But if core is partially blocked then it will eventually starts to leak in the cab, the coolant is what has the anti-corrosive chemicals in it, when passages in the core get blocked up then little coolant can flow so the corrosion starts

The vacuum valve in the engine bay on the heater hose is only used for MAX AC, it cuts off flow thru heater core when you need "max cooling" in the cab
It is not used to vary temp in cab, that is done by the electric blend door only

 

$1.00 the core went.. Ask me how I know... I've done it twice now and just by passed... Sucks as a single guy looking, just bought a nice thick blanket for the ladies.

 

I flushed system and the heater core. However both hoses r not hot. When i flushed the core i used a garden hose and flushed till clear water came out and the flow was ok.
Maybe i should replace the heater core?

 

Yes, its a pain to change but reads like core doesn't have full flow
If only one hose is hot then flow thru core is limited

There are only 2 reasons to have no heat in the cab, well 3 if you count the blower fan, lol, but its pretty easy to tell when its not working
Blend door, in 1995 and up Rangers this door is controlled by an electric motor and the COLD-HOT **** on the dash.
The Blend door directs air coming from the fan to either pass thru the heater core(HOT) or to bypass the heater core(COLD), and can be adjusted anywhere in between full air flow thru core or no air flow thru core

And then there is the heater core itself, as it get plugged up full heat gets less and less until there is no heat to speak of.
The design of the core allows flow just thru the upper area, so the "garden hose test" doesn't mean the lower core has good flow.

The above are really the only two things that can prevent heater from working

Thermostat and radiator have no real bearing on heat in the cab, water pump does, but you would have engine overheating if water pump was failing.
Low coolant level can stop heat in the cab, heater hoses are at high spots on the firewall so they lose coolant first, as they should to keep whats left of the coolant in the engine.


You can "try" to clean out the core
Remove heater hoses at the valve end not the firewall
Point one hose down
Blow into the other hose to clear out any fluid in the core as much as you can
Raise both hoses up
Mix some hot water and CLR or Vinegar, pour it into the core
Let it sit for 15 minutes or so
Blow it out again, you can use garden hose
Then blow it out, get fluid out and REPEAT
Reverse directions each time

There is no IN or OUT on a heater core, that's assigned by where you put the IN and OUT hoses from the engine, which is why its a good idea to reverse these every few years, back flushing the core while you drive

The CLR or Vinegar can remove some build up inside the core, but the problem is it has to be able to get to it, and when passages are blocked.................
But its FREE to try

 

its totally plugged!! I've ordered a new part. Thx ao much for ur help!!

 

Bummer

Thanks for the update

Remember to swap/reverse heater hoses at the firewall every few years, on ANY vehicle, to make the heater cores last longer