Grundfos Geo-Flo Universal Pump Controller Installation, Operating And Maintenance Manual page 19

Troubleshooting (continued)
Screen Color Action / Display
Display = "LOWVOLT W"
Yellow
Display = "FLOW SET-
POINT"
Additional Troubleshooting
Problem
Magna GEO var. speed pump runs
continuously at full speed and does
not respond to controller inputs.
Control displays "2 PUMPS RUN-
NING" but UPS26-99 will not run.
GEO-FLO UNIVERSAL PUMP CONTROLLER: UPC-GEO | 17
Indication
Magna GEO feedback signal
"reports" to controller that
motor has low voltage, but
it is still able to running
(yellow indicates a warn-
ing). Pump performance is
reduced.
Displayed when the
pump(s) are unable to
deliver the flow rate neces-
sary to achieve the set
point (flow or ΔT) input
into the UPC-GEO (i.e. the
pumping system is running
at full speed and cannot
satisfy the user's request).
Possible Cause
Loss of communication with con-
troller. Controller should report
"No Pump" in Status area.
No 230V input power at L2/N2 IN
(i.e. one leg of the 230V input is
disconnected).
No 230V output power at L1/N1
OUT (i.e. one leg of the 230V out-
put is disconnected).
UPS26-99 failure.
- continues -
Possible Cause / Solution
Incorrect power supplied to pump.
Supply correct input to pump.
1. Incorrect flow rate or ΔT value
entered into UPC-GEO. Enter
correct flow rate or ΔT values
into UPC-GEO.
2. Pump system undersized for
installed piping/heat pump
system. Reduce system head
loss. Add an additional pump
to the system.
Solution
Check PWM cable connection at
pump and at controller. Or, may
require isolation relay.
Correct input/output wiring.
The relay L1/N1 and L2/N2 are
rated for 120/208-230V. If a single
leg (Line or Neutral) of the 230V
power is connected to the L2/N2
IN, the relay will energize the L1/
N1 OUT terminals but the 230V
UP26-99 will not run.
Disconnect power. Isolate
UPS26-99 by closing service/flush
valves. Verify UPS26-99 impeller
spins free by removing bleed screw
with a large flathead screwdriver
and attempt to rotate the pump's
shaft with a small flathead screw-
driver. Note that removing bleed
screw will result in fluid/pressure
loss in system so be prepared
with a bucket and/or towels. If
the impeller spins, replace bleed
screw, open service/flush valves,
re-pressurize system, and re-con-
nect power. If pump then runs,
loosen bleed screw and allow a
few drops of water to seep out
to ensure there is no air trapped
in the pump. If impeller does not
turn or the above procedure fails,
replace pump motor.