Heater/thermostat/vacuum problem

[slychicken37]

Currently my 2001 Ranger 2.3L has had some trouble with the heater temperature.

For the past month when I start it (very cold outside) the engine makes a slight singing noise but once warmed up this goes away. Now I havent noticed the sound as much even though it is a little warmer, but to my surprise as of yesterday my truck does not blow hot air any more. Temperature guage is normal, no overheating but absolutely no heat comes from the vents. One strange thing happened to me yesterday on my way home though. As I was driving all of a sudden my temp gauge spikes to way over hot, so I shut of the engine and while coasting restarted it and it was at normal. I cycle the temperature knob and I hear the door actuators moving so I assume they are OK. Any thoughts?

Could it be a bad Thermostat? Blocked Heater Core? Bad Water Pump? Electical Problem of sorts?

Supposed to get cold next week and I like heat.

 

[locovaca]

I would flush and refill your coolant. If you did not have a good mixture the coolant might've froze up in the lines which could cause everything you just described. You can buy a cheap tester which will tell you if you have the mixture right (and the approximate freezing point).