I have a Pacific hot tub with a Balboa heater model number PHT-400. After the tub heats up it goes into flow error. I have removed the filter and open the pressure switch. I also opened all the knife values and removed the filter. Jets seam to be working fine during heating.
It has been suggested to me that it may be either the impeller or the pressure switch. My hut tub has to pumps. One is strictly a circ pump and the other is the high/low for the jets. I have attached two pictures. One is of what I believe is the pressure switch with the valve fully open locate on the left side of the heating tube. The other is what I believe to be a flow sensor switch which is located at the entrance of the circ pump.
Any ideas on where to start diagnosing? Is there any way to test a switch/sensor or an impeller?