in s/h for 4 years but no flowers

[Bud]

you are in grow zone 10b that is ideal for Vandas but for Phals it can be too warm....and you said your thermostat is at 69F constantly....yet the exposure to the southern window will definitely give it warmer temperatures and you have to find out exactly how warm it is in that area and the moisture content in your atmosphere.
You need to give it a colder exposure at night around 60F outdoors then put it back on the window in the day. The exposure to colder temperature will induce it to spike.
the longer the day exposure the more spikes it will produce.

tip:

spike will depend on the length of light exposure and the colder temp at night you give it. (70 to 80 in the day and 50 to 60 at night will give you bigger flatter flowers).
....invest in an electric one gallon humidifier with an oscillating fan....

[Tabbyblack13]

You can also get thermostats for your seedling mats. I have mine set to prevent my plants from getting below 65. There is a probe you stick into a pot and when it gets below that temp the thermostats will turn on the mat.