A dryer doesn't have to be especially hot to work as long as it can move moist air out of the machine.

I'd be suspicious of poor venting if you can detect even moderate heat in the dryer. The vent may be blocked or especially dirty. It may not be properly connected. It might also be simply too long and too many bends to allow sufficient air flow.

What knot2fast says.

Dryers have recommended vent run lengths, that are in the installation instructions. Each 90 degree bend adds 5 feet of length to your run, by just being there. So if you have 25 feet of venting to the outside but have 2, 90 degree turns you now have the equivalent of a 35 foot run, and it may be too long for your dryer. I don't believe the bend coming out of the dryer counts as one of those 5' penalties though, read the manual if available, or check an on line manual.

You want ridged venting duct work, not corrugated metal or plastics. Metal corrugated is ok for the very short run from the machine to the start of the vent if needed, I believe. If a vent run needs to be longer than the recommended length than an auxiliary fan is needed. In apartment buildings that is often the case because of the location of multiple units.

Get the vent cleaned and see what you think. A cheap fix for a big return.

some really good advice, wow.

thanks so much, e & !2f!

-colin