I am having an issue with my Minimax NT. Fan comes on high to purge, then operates at low speed while igniter heats up, gas valve opens and flames start for a second then go off. Fan then switches to high speed to purge and cycle repeats. After a few times, E04 appears on display. Is the vacuum pressure switch not active during low speed mode? Does it only need slow speed mode for sequence to function? Fan seems to be able to operate at two speeds. HELP.
Pentair Minimax E04 error
- Thread starter gmattfp
- Start date
This must be a LoNox unit as the Minimax NT's around here are only single speed blower motors.
Sounds like your flame sensor is not sensing that the burners lit. Pull the flame sensor and clean it with some steel wool and try again.
Sounds like your flame sensor is not sensing that the burners lit. Pull the flame sensor and clean it with some steel wool and try again.
I found that indeed it is a LoNox unit, TSI type. Went to check flame sensor but when I tried to unplug wire, the sensor came out of the unit. The bracket and screw holding it in place have rusted away. I'm afraid of what I might find inside. I can likely make a new bracket but don't know which direction to point flame sensor. To test if sensor is the issue, can I ground the wire and try running the cycle? I don't know how the sensor works. It looks like one wire so I'm assuming it grounds the signal when it heats up. And thoughts on how the sensor works? Thanks.
The E04 error (fan vacuum failure) re-appeared after I replaced the flame sensor, see original fault in original post. Prior to replacing flame sensor, the heater would cycle through but no error code. Seems that in some cases if multiple failures occur, then the error codes don't display. Checked vacuum hose and fan port. Port is clear and hose holds vacuum, (disconnected, plugged one end and sucked on other end. If I jumper the vacuum switch and cycle still does not complete, does it mean the controller board is bad? Anyone have any other possibilities for this error code or trouble shooting possibilities?
Have you pulled the fan motor to check the condition of the squirrel cage?
You can't jumper the pressure switch right away. There is a timing sequence and if you do it to soon you will still an error.
You can't jumper the pressure switch right away. There is a timing sequence and if you do it to soon you will still an error.
Removed cover and blower cage looks okay. Fan blows hard during initial purge cycle. Then cuts back to lower speed. Currently the glow plug turns on when the fan goes to low speed. After it heats up, the gas valve opens and the burners ignite. The fan is then supposed to go to high speed but it doesn't and the gas valve closed. After the gas valves closes, then the fan goes to high speed. Cycle repeats. Is my understanding correct that the ignition sequence will not run if the fan vacuum switch is not working? It must be working because the ignition sequence runs to the point that the gas burners are ignited. Is the switch supposed to hold the contact closed even when the fan is at low speed? I'd hate to replace the $60 vacuum switch if something else is causing the shut down. E04 still comes on after three tries and hard lockout never comes on. I've seen a comment that the E04 is somewhat of a generic code that might be activated by some other fault, (someones discussion with Pentair). Is this true? Is there a logic diagram out there that explains the interlocks beyond the basic sequence description in Pentair's manual?
We don't have very many LoNox units here in FL and I've only worked on one that ended up being replaced due to being rusted out.
Yes if it lights then the vacuum is goods, supposedly. Yes E04 can be a generic error code as well as I have seen that on a few of the non LoNox units. It could be a defective flow valve also.
Here is the manual for the heater. Not sure if it would help you at all.
https://www.parts4heating.com/v/vspfiles/images/pdfs/MiniMaxNTLowNOx.pdf