I think you're using the wrong event. The input range has an event called mousemove , which is activated when the mouse is clicked and in motion. I'll leave you an example with an input range that requests the loading of the temperature:
<!DOCTYPE HTML>
<html>
<head>
<title>Título de la página</title>
<meta charset="UTF-8">
<script>
addEventListener('load',inicio,false);
function inicio()
{
document.getElementById('temperatura').addEventListener('mousemove',cambioTemperatura,false);
}
function cambioTemperatura()
{
document.getElementById('temp').innerHTML=document.getElementById('temperatura').value;
}
</script>
</head>
<body>
<form action="#">
Seleccione una temperatura:
<input type="range" id="temperatura" min="0" max="100">
<span id="temp">0</span>
<br>
<input type="submit" value="Confirmar">
</form>
</body>
</html>