Hytec Kohler Model LM34520 air jet swtich not working. 4 years old and last use, the push button stopped working. Cannot see connection detail at switch/button end but disconnected at motor and and can blow air through line. Is there access point from inside tub to pull switch trim off?

SOURCE: Kohler bathtub spa does not work at all

If the air tube is still connected to the air button on the side of the tub and you are pushing it with no results then either the motor is no good, the air button is no good or the air switch in the box is no good.
process of elimination, start with the pump. take the switch off the motor or out of the box and make sure you can get the motor to come on. If the motor comes on then move to the air switch and hook it back up and see if you can blow into the air switch with a new air button or a straw and see if the switch will activate the pump. if it does then you most likely have a bad air button ($12). If you cannot get it to activate the pump then the air switch is bad ($21).

SOURCE: How to identify make and model of old whirlpool tub?

This is a problem common to all whirlpool/air jet style tubs. The pumps become air locked due to the water evaporating from lack of use. All tubs need, and have, SOME means of priming the pump, this is most likely what the problem was, originally, for you. This time in particular you found it to be electrical in nature but for future reference, for you and all who have these style of tubs, I am putting this out there. Some where on the tub, usually along the top edge of the tub is a vent knob that controls the amount of air that the pump is allowed to mix with the water for the jets, usually by closing this valve all the way (tub needs to be full of water of course) and running the pump for a minute or 2, you should be able to get the pump pumping water again, if not you may need to do something else with your particular set-up to get it purged of air, the pumps in jacuzzi tubs are designed to pump water, not air, so if the motor is running but you get no jet action, your most likely air locked and need to prime pump/purge air.

SOURCE: bathtub jets don't work

how do you turn the tub on/off? if it is a Logo that you touch when the tub is full of water you get in then it we need to know the model number off the box under the bathtub. it will have several wires coming out of it including a wire going to the pump.

SOURCE: Two jets stopped working

Most of these jets turn to close. Check if you turn the nozzle. Hope it helps

SOURCE: Where to buy a Kohler air switch and air button?

Most of the control buttons on a tub are not electrical. These buttons are connected to an air line that runs to the motor. Sometimes an aggressive button push can literally blow the air line right off of the bottom of the button.
This problem is as easy to fix as it sounds. Find the loose air line and push it back onto the button. You will need to open up your access panel. Bring a flashlight.
Be sure to check the connection at the motor too. Good luck