I had put a 3 gauge pod in my truck back in the summer and had a friend install it. To get the water gauge to work he disconnected the orginal sending unit for the factory gauge and hooked the new one up where the orignal one was. Now in the winter it takes forever for my truck's heater to work. I was wondering if this problem is related to disconnecting the factory gauge.
Agreed with Doofy...the guage installation shouldn't affect the engine temp.
Depending on how cold it is where you are plays into it too. As well As, how far you're driving before your shutting down. for example, if the air temp is -10* F and you're driving <10 miles there is high probabilty it won't reach operating temp nor get very warm inside.
yes the thermostat could be getting weak or stuck...take your pick.
check that 1st.
the water pump could not be moving coolant as well too. Not as likely but should be checked.
the heater core could be getting plugged with sediment from the cooling system and or is nearing failure. check the heater hoses going to the fire wall after it is been running awhile....with heater going full blast...if one hose feel very warm and the other
very much cooler....then you're having a circulation issue...now this could be from a water pump not moving water very well... or...a plugged up heater core.
If water pump is not moving coollant or doing it poorly,
generally you'll see the engine up to operating temp or just a tad on the warm side but lacking heat inside.
generally if the heater core is plugged up to the point of lack of heat...it is about to spring leaks & you'll get a sweet funny smell inside the cab as you thermostat opens and maybe a haze over the inside of the windshield... and replacement is the best solution.
when was the last time you flushed you coolant system??
if you feel the heater core is solid...remove the heater hoses and flush that as well moving water both ways thru the core.
Now there MIGHT be a vacuum diaphram that control a heater damper door.
or a control cable to a pin (like a throttle cable on push mower) that might be broken not letting you adjust the the amount of heat you desire...just depends on your vintage of ranger??? so you might want to make sure that your climate controls are functioning