99 Ranger No Heat, Buried on C

[Weezknight]

I'm no stranger to the fact that my Ranger has run cold from Day 1, however, this morning (coldest morning this year) things got weird.

First, I warmed the truck for about 10 minutes (with defroster on since the frost was double layer thick on the windshield), everything was warm when I got in.

I then switched over to full heat cabin & floor. About 5 minutes into my drive to work I noticed I was getting colder, not hotter. The check engine light popped on, and the temperature gauge buried itself to the bottom. Continued air out of the vents was hardly warm.

Instant guess is the thermostat is stuck open. Anything else I should check? The only reason I ask is because the check engine lit up.

 

[mojoranger]

Had a van do that one time. Turned out that the coolant was mostly water so it froze. Since it was not circulating through the engine the temperature gage never registered hot. Ended up seizing the engine. Hopefully not the case hear but wouldnt hurt to check.

 

[Weezknight]

I'm going to have to check out the coolant thing, as well. Just took it for a spin during my lunch break, and it was slow to warm up, at first, but the heat started working again, now that the sun is out.

It still struggled to get over the "C", though. I may just switch out the thermostat (since it's very old), and maybe put new coolant in, as well, when I do the switchout.

 

[Gary101386]

have you recently done anything to the cooling system? replace a hose, radiator, water pump? If so you may have some air in the system...

from cold, start your truck with the radiator cap off and run your defrostor on high. watch your coolant for 10-15 mins and top it off as needed... that may do the trick.

Best bet is coolant level or T-Stat...

 

[srteach]

Thermostat is most likely.
When water freezes, it expands (at about 4 degrees C.) This could cause a burst open radiator. Happened to me before. Check the rad for leaks if your coolant has a high freezing point. Maybe just replace the coolant if you haven't done that before now.