Pressure switch keeps getting stuck / temperature issues

[tarheeltub7977]

Hi friends, longtime hot tub owner here.  My old trusty Cal Spa (with Applied Computer Control pack) is continually having an issue with the pressure switch getting stuck open, on both high and low ... so my temp drops over time bc the heater is not running.  If I hear it trying to turn on I can go out there and turn the jets off and on a few times and it will getting "unstuck" and start heating again, but by then the temp has usually dropped to the mid 90's and it takes hours to get back to 104, where we like to use it.

I had this same issue toward the end of last season so I replaced the pressure switch at the start of this season .. no change.  I replaced my heater coil 2 years ago.

My water level is always fine - I do have a slow leak but I keep the water topped off (going to address the leaky union next spring when the weather warms back up and tub season is over).  I recently did a fresh fill and made sure to purge the lines before turning the heat back on, I dont believe it's an air lock issue.

So why would I keep getting the "PSoH" and "PSoL" switch errors??  Thanks in advance.

[Cusser]

I'm guessing my own CalSpa (1988) is older than yours; I've had to adjust my flow switch several times over the years.  I've even thought about drilling the housing and tapping for a more-modern screw-in type of flow switch.

[tarheeltub7977]

yeah mine is not THAT old.  i have a pretty standard control pack and flow-thru heater tube (or whatever it's called).