Pentair MinMax NT not blowing

Florida · Oct 18, 2015

I have a Pentair MinMax NT propane gas heater. It's about 10 years old. I've had to replace sensors before and make some repairs where critters chewed on cables and tubes. It had been working okay. I recently tried to turn it on. Temperature shows 79, which is accurate. Heat set to 98 for the spa. When I push the spa button the pressure switch light comes on and then thermostat light comes on but it doesn't get any further. The blower doesn't start. There are no error codes and no warning lights on the inside, including on the back of the circuit board.

I'm not sure where to start looking without an error code. It could be a blower problem, electrical, fuse.

Any advice on where I should start?

Thanks.

ps0303 · Oct 18, 2015

If it's not showing an error code on the display then it could be the blower motor. Does the motor spin OK? With the unit powered off, remove the top and carefully try to spin the motor. I can usually get a finger on the shaft end and spin it. If it spins freely then I would have to wonder if the run start capacitor is OK.

Florida · Oct 19, 2015

Yes, the motor spins freely and smoothly. I see the large start capacity attached to the motor housing. You think I should try replacing it?

ps0303 · Oct 19, 2015

Try this. Turn the unit on and set it to run and then spin the motor and see if it takes off. If it does and runs, then I would suspect the capacitor. I use a amp meter to detect if the capacitor is working or not. You don't have any automation or remote system attached to this do you?

Florida · Oct 20, 2015

The motor won't spin up by turning the shaft, though it is very hot. I tried it with and without the capacitor in place because I took it out to order a replacement.

The spa does have an automatic control but I don't use it anymore. The actuators stopped working so I turn everything on manually.

Florida · Oct 21, 2015

I replaced the capacitor and it didn't help. I'm still concerned why the motor feels so hot even when the pool heater is in a mode where it would not be heating. It's like the motor is somehow drawing power, since that's the only way it could be hot like that. I've turned the heater completely off from the inside for now, so that no temperature or anything shows.

Does it sound like the motor itself is shot? If that's the case, I think I would rather put the money toward a new unit.

Any recommendations on a replacement for a 250K BTU gas heater?

Thanks.

ps0303 · Oct 21, 2015

The only way to know for sure if the motor is shot is to put a new on on and see what happens. I've seen motors that won't spin and then when you spin it by hand it starts going. However, seems like you have tried that and it doesn't spin.

I would definitely recommend a Raypak 266K unit to replace this. This unit does not have a blower motor to contend with like all the other units do. It's a straight forward unit that does an excellent job at heating water.

Florida · Oct 22, 2015

I took another look at the heater and if I waited long enough I got an E04 error code. I was looking at the indicator lights again inside to try to get more information when I noticed a severed wire. It had not been obvious earlier because one end was tied up in a bundle of wires with a zip tie and the other end was kind of hidden. I've had rodents in the heater before, so I wasn't too surprised. When I spliced the wires back together, the blower and heater started up! Even with the original capacitor. I guess I should throw some rat poison in the bottom of the unit. We don't use the heater much in the summer, mainly just the spa in the winter. So it sits for a while without being used. I should try to remember to check on it more often.

Thanks for your help, Paul! It looks like the heater might have a little life left in it yet.