KL has plenty of air-conditioned taxis, which queue up at designated taxi stops across the city. You can also flag down moving taxis, but drivers will stop only if there is a convenient place to pull over (these are harder to come by when it's raining and during peak hours). Fares start at RM3 for the first three minutes, with an additional 25 sen for each 36 seconds. From midnight to 6am there’s a surcharge of 50% on the metered fare, and extra passengers (more than two) add 20 sen each to the starting fare. Blue taxis are newer and more comfortable and start at RM6 for the first three minutes and RM1 for each additional 36 seconds. Night surcharges of 50% also apply.
Unfortunately, some drivers refuse to use the meter, even though this is a legal requirement. Taxi drivers lingering outside luxury hotels or tourist hot spots such as KL Bird Park are especially guilty of this behaviour. Note that KL Sentral and some large malls such as Pavilion and Suria KLCC have a coupon system for taxis where you pay in advance at a slightly higher fee than the meter.
One of the easiest ways to get a taxi is to download the app Grab to your smartphone or tablet. This way you will also know in advance what your fare will be.