Max-E-Therm 400 power

genrel

Member
Jun 30, 2020
7
REL4blue
Problems started when the heater would shut down when the spa was turned on. It would run up to 86 degrees and shut down. Not happy about the high cost of parts when the repair guys shows up, I punted! I order a 42001-0053S Thermistor and installed it. Now, no power to the heater at all! Chances the new part is bad? Installation step missed? The ignitor was replaced two months ago, $400. The unit inside is clean, no palm rats...
 

JamesW

TFP Expert
Mar 2, 2011
19,408
We're going to need lots more information. Pictures of everything including in the metal Fenwal box. Pictures of the whole system. Age of heater. Automation? Do you know how to check for incoming voltage? What supplies power to the heater?
 

genrel

Member
Jun 30, 2020
7
REL4blue
Well your picture request lead me to turn everything on, the pool temp setting was low. Adjusting brought power back, the heater fired but stopped at 93 degrees. Now i see the service light is on. I guess back to the start of my problems, except that i am a few degrees higher in temp. Pictures won't load as the file size limits the upload. Is there another limiter worth trying to replace as a repair guess?
 

JamesW

TFP Expert
Mar 2, 2011
19,408
We're still going to need lots more information. Pictures of everything including in the metal Fenwal box. Pictures of the whole system. Age of heater. Automation? What displays on the display when the heater starts up?

On startup, the heater should show 888,128 and then r X where X is the software revision and then the water temperature.

Once the water temperature displays, press the up button to see what the set temperature is.

Can you increase the set temperature to 104 degrees?

Is the water temperature readout accurate?

When the heater runs, press and hold the Pool On button until the exhaust temperature displays.


 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
19,408
Once the water temperature displays, press the up button to see what the set temperature is.

Can you increase the set temperature to 104 degrees?

Is the water temperature readout accurate?
 

genrel

Member
Jun 30, 2020
7
REL4blue
James, thank you for your replies. I have taken new pictures and they are larger in size, so back to figuring this out. I will try again, but I have to pay attention to my day job so might be tomorrow, am. I can say I didn't get a the heater to show 888,128 and then r X where X is the software revision. (Further I do not understand.) I get get a heat reading of 275 and a water reading of 90. Will try and follow your instructions again when I learn how to reduce the image size and send.
 

genrel

Member
Jun 30, 2020
7
REL4blue
I viewed the helpful video on error lights on the back of the user panel. Tried again to attach an image, with HDR turned off and still too large (5826 KB). The heater was turned on, started heating the spa and shut off at 93 degrees. Looking at the back of the panel or circuit board, I see a new light indicating a problem found (?). It is located on the bottom right corner of the board. It looks to be "LED11" with red light top and bottom. I know a picture is better but knowing the location on this Max-E-Therm 400, can this tell the specific part to replace?
 

JamesW

TFP Expert
Mar 2, 2011
19,408
The following are the LEDs:

  1. .....PS (Pressure Switch)
  2. .....HLS (High Limit Switch)
  3. .....SFS (Stack Flue Sensor)
  4. .....AFS (Air Flow Switch)
  5. .....AGS (Automatic Gas Shutoff).
  6. .....Service System
  7. .....Thermistor
  8. .....Heating
  9. .....Pool On
  10. ...Spa On
  11. ...Service Heater.