Pentair Pool Products MiniMax NT Series Service Manual page 35

Troubleshooting
1. Check the 3 lights on the back of the Control Board. These 3 lights are
connected to 3 different controls in this order: #1 – High Limit,
#2 – Thermal Fuse, #3 – Gas Valve.
2. If all of the lights are out, the High Limit safety switches are keeping the
heater off. If the inlet water reaches 115 degrees or if the water from the heat
exchanger reaches 150 degrees the heater will not fire. Check for proper
water flow through heater. If water flow is correct, allow heater to cool and
check continuity of the High Limit Switches. If either switch shows an open
circuit when the heater is cool, replace the switch. See Figure 31.
3. If only the "High Limit" light is 'ON' (i.e. only one green light is on), the
Thermal Fuse circuit is keeping the heater off. If there is evidence of flame
roll-out at the Thermal Fuse location, it is probably burned out. Check
Thermal Fuse for continuity, if good, check wiring for continuity. If Thermal
Fuse is burned out, find reason for roll-out before putting heater back into
service. See Figure 32.
4. If the "High Limit" and "Thermal Fuse" lights are ON (i.e. two green lights
ON), Check for 24 VAC at 24 VAC terminal on Ignition Module. If none,
check connections and wire back to Transformer. See Figure 33.
5. Check for 24 VAC at IND terminal on Ignition Module. If none, check
connections and wire back to Control Board and then for 24 VAC at orange
wire at connector at Control Board.
6. Check Fan connection on module (F1 & F2) for continuity if electric supply is
120VAC by removing plug and checking continuity across terminals. If no
continuity, module is bad. If the heater electric supply is 240 VAC, leave plug
in place and check for 120 volts from F1 to ground. If no voltage, module is
bad. See Figure 34.
7. Check connections and wires from module and 120/240 plug connectors to fan
motor. Replace fan motor if necessary.
Figure 35.
Rev. B 2-11-04
POWER / T-STAT / AUX / PRESS / SERVICE
Fan Not Running
35
Figure 31.
Figure 32.
Figure 33.
Figure 34.
P/N NTSM03