So I just bought this truck a couple weeks ago. Since I've gotten it I've noticed that the coolant temperature gauge doesn't work. At first I thought it was the cluster. So I swapped it out. But the problem still persists. I've also noticed that the heat is pretty weak. It blows just fine, just the heat is blowing out is warm and not hot; and in 2 degree weather I dread driving the thing. I did notice that one time, just once, the gauge started moving up. But I don't think it was reading correctly. What would cause all of this? Is it the coolant temp sensor? Is it the thermostat? I'm pretty new to rangers as this is my first one. New to Ford in general haha. Any help would be appreciated. I don't like freezing my *** off driving to work!

 

Welcome to the forum

After engine is warmed up and heater has been on, open the hood and feel the heater hoses at the firewall.
One will be warmer that the other
If one is HOT and the other much cooler then heater core is probably clogged up and will need to be back flushed, mark which hose is hotter regardless, thats the IN from the engine hose.

If the IN hose is just luke warm, like heat inside cab, then someone may have put in the wrong thermostat or thermostat is stuck open.

Ford uses 192 to 195degF thermostats on all its engines.
In the old days engines used 180degF thermostats

With research and new designs for cooling systems it was found that running engine coolant above 190degF was best for engine and oil life and as a bonus better MPG.

So if temp gauge is reading very low it is working but in the cold weather engine just can't heat up, and if engine can't heat up then neither can heater in the cab.
Thermostat's purpose is to let the engine coolant heat up to 190degF so it can run better, and then pass any EXTRA heat, above 220degF, over to the radiator if even needed, in cold climates radiator may only get a little warm.

So to test if thermostat is stuck open
Start cold engine
Open the hood and feel upper rad hose by the engine end, should be cold of course
Leave engine idling and wait 3 minutes or so and feel it again
If upper hose is warming up then thermostat is open and circulating coolant thru the radiator, and it shouldn't be open until coolant gets to 190degF, which takes 5 to 10 minutes, at least, 10 minutes if cold outside

Thermostats are suppose to "fail open", other wise engine could over heat, so it may just be time to change it

The 2.3l Lima engine doesn't generate a lot of heat in general, so they also make a 205degF thermostat for them for use in very cold climates.
A working thermostat has nothing to do with an engine overheating, EVER
If your cooling system is low on coolant or has other problems then the difference between 180degF and 210degF as a starting point of the over heating is about 20 second of time, lol.

 

I had the same problem with my 1998 Ranger 2.5. No heat and a temperature gauge that barely moved.

The first thing I tried was to replace the temperature sender. I used an aftermarket sender because it was cheap. No change in the gauge.

Next I changed the thermostat. Again I used an aftermarket unit because it was relatively cheap. The aftermarket unit didn't seat as well as the original did, but I tried it anyway. Still no change in the gauge and no heat.

I then disconnected both heater hoses and used a garden hose to flush the heater core multiple times in both directions. The black crud that came out of the heater core was incredible. I flushed until it ran clean in both directions.

Now I had a little bit of heat, but the gauge still didn't work.

My next step was to replace the thermostat again, but this time with a pricey ($45 Cdn) Ford unit. This one seated nicely like it should and I now had lots of heat, but the gauge still didn't work.

So it was off to Ford again to get a factory temperature sender for only $51 Cdn. Ouch!!! That actually took two trips because the first time they ordered the sensor for the computer, not the sender for the gauge even though I was very specific in the description of what I wanted. (The two are not interchangeable)

The final result is that I now have a working temperature gauge and lots of heat in the cabin. Last week was -25C (-13F) here and the cabin heated up nicely

It was an expensive and time consuming exercise, but the end result was worth it.