I have a Pentair Mastertemp 400 with an AFS light on. The heater turns on and runs for 10 seconds and turns off and throws the light on. Before this light came on I replaced the pressure switch, high limit switch, thermistor, manifold bypass valve, and control board due to an issue caused by the bypass valve in the manifold. When removing my manifold I noticed my coils were in good shape and didn't have and water in the heat exchanger. I put my ohm meter on the afs switch and it is good. When I bypass the switch and turn the heater on it runs and then starts getting really loud and shaky before I shut it off so I don't mess something up. Any help would be greatly appreciated. Thanks
Pentair master temp 400 afs light
- Thread starter bdenhart06
- Start date
-
- Tags
- afs light pentair 400
I did and no water is in the canister. I also pulled off the blower and looked down in canister
From what I saw when I had the blower off it didn't look that dirty. Is this a common problem? Could it be the igniter control module or the blower not blowing hard enough? It ran all day long 2 days ago after I changed all the parts out with no issues and once I went to turn it on yesterday it threw the afs code.
That might be due to poor water flow or air flow. If you're confident about the water flow, I think that you're probably going to have to check the heat exchanger for sooting.
If it was a water flow issue, the high limit led would probably be coming on.
Since you're getting an AFS led, that points to an airflow problem.
Check the blower for signs of mouse nests. If the blower is clear, check the heat exchanger.
The Mastertemp and the Maxetherm are the same heater except for the outer shell.
Here are two videos of the teardown and cleaning.
Here are two videos of the teardown and cleaning.
Check the thermal regulator to make sure that it's ok.
Try running the heater with the thermal regulator left out to see if that makes any difference.
When the heater starts, press and hold the On button to make the exhaust temperature display.
If the heater sounds bad on startup, shut it off quickly.
Hard to tell. At this point it's probably best to pull it out and clean it up.
When you put the manifold back on, you're going to need new gaskets.
Hopefully, that will resolve the air flow issue.
Maybe check the gas pressure to see if it's off enough to cause sooting.
Also, be alert to any signs of mice. They can sometimes build a nest in the blower, which can interfere with the airflow
When you put the manifold back on, you're going to need new gaskets.
Hopefully, that will resolve the air flow issue.
Maybe check the gas pressure to see if it's off enough to cause sooting.
Also, be alert to any signs of mice. They can sometimes build a nest in the blower, which can interfere with the airflow
Last edited:
I will go ahead and clean them. I just replaced the gasket and orings in the manifold when I replaced the bypass valve so I should be good. When I pulled the blower out last night I didn't see anything obstructing it. I will check the gas.
The hole doesn't look big enough to affect the airflow. However, it's not safe to use the heater with a hole in the tub.
It's probably time to replace the heater.
It's probably time to replace the heater.
The tub looks like it has multiple holes.
That makes me suspect that the heat exchanger might have been leaking.
That makes me suspect that the heat exchanger might have been leaking.
I just patched up the hole and turned it on and now it's not igniting. Can I put an ohm meter on the igniter and see if its good? its still throwing a afs light.
the heat exchanger looks like it has been replaced because there was rtv sealant on everything. Doesn't look like it was done like that from the manufacture. the heater is a 2009 and I bought this house in 2016
once I looked at it again this morning I left one of the gas valves off so when I started it up again it ignited and ran for 10 seconds and shut back off and through the afs light on. I by passed the afs switch and put a ohm meter on it and it shows good. I just put a brand new control board last week. Do you think it could be a ignition control module?