2001 Sundance Altamar Circulation Pump Cycles Off When Set Temp is Achieved

[Cabdriver]

Hey all, need some help with a CP issue on a 2001 Sundance pump altamar two pumps plus circ, filter has only seen a few weeks of use but has been thoroughly cleaned.

Tub has been in a sunroom its whole life and overall, very pristine condition, 23 year old unit - all pumps and equipment are original (came with the house I bought 3 years ago). Replaced the flow switch and temp sensor (due to flashing flow issues and OH error and strange temp readings) in the past two weeks and shortly after the circulation pump gave up completely.

Replaced the pump with a new Laing, filled it properly via the filter intake pipe, when I fired it up, no issues (no pump cavitation etc.).  It ran for 48 hours no problems and then I got a solid flow warning.

First experiment: with the set temp at or below water temp (there is a reason why I mention this):

1. Reset the breaker multiple times and the CP starts pumping then stops after a two seconds followed by solid FLO after like 10 seconds 
2. Reset the breaker and fired the main jet pump immediately and the tub stays on, no FLO error - unless I turn off the jets, then the CP continues to work for a few seconds, then it shuts off followed by solid FLO error

Second experiment: Did the same as above but raised the water temp by a few degrees (the only change):

1. Reset the breaker, CP fires, heater fires, CP keeps going no issues, will run (hours even) until it reaches target temp, therein the heater turns off followed by circ turning off
2. I tested this theory multiple times, whether its cold or hot, if I raise the temp a few degrees, minimally, above water temp, the circ will work fine until it reaches the set temp

To test the flow switch, I performed the following:

1. I tested the flow switch wiring just to make sure all is well - no issues
2. I looped the flow pin at the harness to mimic a constant closed switch and what I described above did not change, so this did not change the outcome of either experiments above

So in conclusion, this all leads me to believe that the switch is ok, the circ pump is ok and the circ pump power gets cut when the heater turns off and/or the circ pump is almost immediately shut off if the heater is not activated.

Why is the circ pump turning off when the heater turns off - unit is on 24 hour circ pump duration

Thanks

[CanadianSpaTech]

Is it in Economy mode? 

https://www.thespaworks.com/sites/default/files/2006_sundance_880_series_owners_manual.pdf

[Cabdriver]

Got a new observation, it has been coming out of FLO lockdown to perform the filtering cycles, then, if the water temp is below the set temp it works the heater and circ until it achieves the set temp then shuts off the circ followed by going into solid FLO.