I had this happen on my 2001 S-10. I had a very slow coolant leak and when the coolant would get low I could hear what sounded like water flowing from around the heater. At first I thought I had water built up inside the A/C evaporator which was gurgling, but finally realized it was a coolant problem.
Once I fixed my leak and topped off the coolant the noise was gone.
Hope this helps.
It sounds like it might be in your coolant system. heater core maybe? Or maybe a sticking thermostat.
It might. Does the sound follow the space heater to a different outlet? If you place your head between the space heater and the outlet, does the hissing sound come from the wall, or from the heater? Sometimes different sounds come from different sides of applicances, and these sounds can reflect off the wall. A standard vacuum cleaner and some electric irons draw about the same current as a space heater. Is the sound present with either of those plugged into the same outlet instead? It might be a snake, saying "thank you" for the warmth.
I'm guessing it could be the sound of coolant flowing through the heater core. Checking your coolant level and topping it off may quiet the sound.
Most are up underneath the dashboard. Turn on the heater blower motor and listen where the sound is coming from. The heater core is behind that sound.
Water flowing sounds can be spelled as "splashing," "gurgling," or "bubbling," depending on the specific sound you're describing. For a gentle flow, you might use "trickling" or "rushing." Each term captures different nuances of flowing water.
Water curves sounds because it is flowing, making it echo or sound flat and gargled at the same time.
Sounds like a lot of rain and wind coming through.
Bengali sounds melodious and rhythmic, with soft intonations and flowing sounds. It is characterized by nasalized vowels and a variety of unique consonant sounds. The language has a musical quality that can be soothing to the ears.
The system needs to be bled, there is still some air in the piping causing the noise you are hearing.
Possible diff. bearings
well your ears can tell whether sound is coming from behing or infront of you. there is another way though if sound is behind you it is quiter which means if sound is in front of you it is louder
A gentle flowing stream or a rhythmic heartbeat are examples of pleasant sounds with a regular wave pattern.