Hi, it takes over 20 min to get heat from my 2005 Honda Accord LX Coupe. But when it heats up, it is very hot and I can feel it from vents. Is this normal or something wrong with thermostat? Thx.

 

does it take 20 minutes for the gauge to register, or does the car warm up normally, and the heater just takes 20 minutes?

 

The gauge stays at "cold" side during most of 20min, gradually climbing/warming up, then I feel the heat coming out. Before that, it basically has no heat except the cold air if turning on the fan. My other car warms up about 5min in the winter time and you can feel the warm air coming out of vent, but not for my Honda.

 

That does sound like the thermostat sticking open.
4-cyl or V-6?

 

Agree, shouldn't take more than 4-5 minutes to reach operating temp, if that. LX coupe is probably a 4 cyl.

 

Put a new thermostat in it.

 

I read online regarding to "thermostat stuck open" and most people mentioned that you should not get enough heat in especially in winter time but I got heat after driving like 30min and actually it is pretty hot and I have tuned it down little. is this still related to "thermostat stuck open"?

 

Seems like it's stuck in some partially-open position. Or more likely it IS working for the most part, but something is preventing it from closing completely. Either way, you need to take it out & see.

Then for the price of a new one it makes the most sense to replace it.

If it were able to close fully, it wouldn't take so long to heat up.

When you put the new one in, look at the gasket. There's a slit around the inside of the gasket, so the gasket fits over the sharp outer edge & covers both sides. Watch the position of the gasket having little cut-outs for the vent-hole and support posts. It should only fit one way. Again, when fitting the thermostat (with gasket) into the housing, there's a couple tabs that fit into recesses so it should only go in one way.

 

This is how the thermostat assembly looks for your car:

 

Oh crud. I forgot we were talking about a 2005...

Forget the stuff about the gasket on the edge of the T-stat. But it DOES sound like it's unable to close completely.