Mastertemp 400 heater AFS light

[aperez0209]

Hello.. new to the forum myself, and I have a doozy...
Pentair MasterTemp 400 gets to a certain temperature and shuts off with an AFS error. I then set the temperature to whatever it shut off at, the "Check Heater" light turns off, then I raise the temperature setting by a couple of degrees, and the heater turns on.
This cycle repeats until I get it up to the desired temperature.. any ideas??

 

[1poolman1]

Hello.. new to the forum myself, and I have a doozy...
Pentair MasterTemp 400 gets to a certain temperature and shuts off with an AFS error. I then set the temperature to whatever it shut off at, the "Check Heater" light turns off, then I raise the temperature setting by a couple of degrees, and the heater turns on.
This cycle repeats until I get it up to the desired temperature.. any ideas??

On the fan orifice there are 2 hoses that run to the AFS. Be sure both are on their respective connection and don't have holes (usually rodent damage) or cracks. Place to start.

 

[aperez0209]

Already checked. No rodent damage.
How much vacuum is pulled by the fan?
When the blower started, I put my hand over the air orifice and felt like plenty of suction.

 

[ajw22]

Are you sure you are getting an AFS error?

Your symptoms sounds like a bad thermal regulator or bypass valve. I would check those.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[aperez0209]

Are you sure you are getting an AFS error?

Your symptoms sounds like a bad thermal regulator or bypass valve. I would check those.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Yes..
Turned over the control panel.
AFS error code light on.
Here the other strange thing...
The heater works well until the water temperature reaches 85°F.
AFS error turns on..
I then have to play with the temperature settings until the maximum temperature is reached.
I've replaced:
AFS switch
Thermistor
High Limit switch
Stack flue sensor

Any ideas??

 

[ajw22]

Check the thermal regulator and bypass valve.

 

[aperez0209]

The manifold bypass valve?
Am I checking for corrosion, stuck spring?
Thermal Regulator Kit?

 

[aperez0209]

The manifold bypass valve?
Am I checking for corrosion, stuck spring?
Thermal Regulator Kit?

Thanks for getting back to me by the way!

 

[ajw22]

The manifold bypass valve?
Am I checking for corrosion, stuck spring?
Thermal Regulator Kit?

Read Pentair MasterTemp Heaters - Further Reading

 

[aperez0209]

Thanks!