Hey All,
Im new to this forum, joined hoping someone could help me diagnose an issue im having with my 2000 Ranger. Previous owner really did a number on this thing, screwed up about everything he could...
main issue right now is winter is on the way and im getting no heat. Ive fixed a few things thinking that was my issue but no luck so far:
First fix: the coolant temp gauge stays at 0 at all times (may go up an eightth of the way sometimes), my first thought was thermostat was stuck open and it wasnt getting a chance to heat up. pulled off the housing and turns out he removed it all together. so i got a new one. Still no heat still no temp reading.

second fix: thought maybe the valve that controls flow into the heater core was bad, turns out the guy had a broken vacuum line and just electrical taped it together. Fixed the vacuum leak. still no heat or reading.

Thought the gauge was bad i attached the wire to a ground and the gauge reacted ( only went up about a quarter of the way, not sure if that is an issue). the actual actuator dial in the cabin had been messed with as well before i bought but seems fine, i feel like that wouldnt be the issue if the gauge isnt working properly.

Any tips, suggestions, things i should check?

Thanks in advance.

 

Gauge or wire to gauge is bad
Temp gauge should go all the way up to HOT if you ground the sender wire

After engine is warmed up, feel the two heater hoses at the firewall, both should be hot than means there is good flow thru the heater core, if neither is hot then the heater bypass valve is stuck close, unhook its vacuum hose, start engine and see if heater hoses at the firewall are heating up

If only one heater hose was warm then heater core is plugged up, have to pull the dash back to change it, so try to unclogged it


Blend Door actuator is a common cause of No Heat, or Always heat
So after engine is warmed up turn temp **** to HOT, leave engine running
Turn Fan OFF
Count to 10 slowly
Turn fan ON
Should feel warmer air coming out but just briefly if heater core is clogged

 

Thanks, you’re the man! This definitely helps.

with the vacuum line fixed if I unhook it it does open and close not sure if that means it’s still functional. While the car is running the hoses running to the heater core are warm but definitely not hot like there is good flow. I’ll test it with the vacuum unhooked and see what happens.

with the bad gauge do I replace the whole cluster or is there a module behind each gauge on the cluster?
thanks again!

 

Also correct me if I’m wrong shouldn’t this valve be the other way to restrict flow into the heater core?

 

Is it a 2 hose or 4 hose valve?
Showing 2 hose on 2000 3.0l, so direction shouldn't matter

It should only ever have vacuum(valve closed) when cab selector is on OFF or MAX AC, all other setting should have coolant flowing thru heater core, no vacuum at the valve
Vacuum comes from the Vacuum matrix inside the cab, not from engine bay vacuum

Feel upper rad hose after warm up, heater hoses should be at least that hot if not a little hotter

 

so weirdly enough the intake side was colder than the out, maybe just because it’s closer to the block. I’m going to try a flush tomorrow, hopefully that solves the issue

 

So making progress:
flushed out the heater core it was definitely clogged with rust. Finally not cold air any more, more lukewarm.
top of the thermostat housing is warm almost immediately which makes me think the thermostat may be stuck open (even though I just replaced it…)

would I still need to replace the sensor and gauge if everything else is functional? Or would that effect heat output as well

 

If temp gauge doesn't go to HOT when you ground the sender wire then the wire or gauge is bad, has nothing to do with actual temp of engine/coolant

Yes, if upper radiator hose(not housing) is heating up in the first few minutes then thermostat is open too much
Radiator is there to provide Extra Cooling, it may not even be used in winter months with some engines
So upper radiator hose should stay cool at least for first 5 to 8 min with engine running

After you blow out the heater core you can fill it with hot water mixed with CLR(or vinegar, but not both) and wait 20min, then blow it out again
Reverse directions and repeat
Should get a little better each time but can't clean it out completely

 

A trick you can use to get the most heat in the cab when heater core is not flowing too well is to unplug the Heater Bypass valve's vacuum hose, so valve is always open, put a plug in the end of the vacuum hose
Put selector in cab on MAX AC

MAX AC setting does two things, it would normally send vacuum to Bypass valve closing it, and it also closes the Fresh Air Vent so air for the fan/blower is sucked in from the cab, from under the glove box, instead of from outside

In the summer it gives the AC evaporator cooler cab air to cool down even more, instead of 90+deg air from outside
But in the winter, with bypass valve disabled, it will pull in the warmer cab air to heat it up even more, instead of the much colder outside air

No reason to do this if heater core is working OK, because you don't need 180+deg heat in a cab, lol, but if heater core is partially blocked you are trying to squeeze out as much heat as possible
Also try running the fan at lower speeds to allow the heater core to build heat as the air passes thru it from the fan

 

Good to know! I may give that a try