Pentair MasterTemp 400 AFS Light on

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Henry121083

Silver Supporter
Aug 10, 2018
114
Newtown
Hi All,

I have a MasterTemp 400 that is getting power (board lights up) but I am getting a service heater LED on and a "click" when i hit the spa button. Nothing is firing and the blower isn't turning on.

It's a propane heater, when I turn the propane on - I am not sure if propane is actually getting to the heater from the tank. (usually when I turn the valve at the heater i can feel the pressure of the gas moving in the pipes)

My question is, if propane wasn't getting to the heater would it cause the click no fire and no blower turning on?

Any help is appreciated

thanks
henry
 
Moved from here.
ajw22 said:
AFS does not turn on the blower. Sequence is blower motor should turn on, AFS senses air flow, and switch closes to start ignition sequence.

Rat probably chewed up wire powering blower motor. Can you turn blower by hand? Motor could be seized.
Click to expand...

I am having a similar problem (minus the rodents) It seems like you're the expert on heaters.

Mine is clicking but no ignition and no blower. I am not sure gas is getting into the heater - would this happen if gas wasn't getting in? (maybe bad regulator at tank or something)
 
Last edited by a moderator:
Hi All,

I have a MasterTemp 400 that is getting power (board lights up) but I am getting a service heater LED on and a "click" when i hit the spa button. Nothing is firing and the blower isn't turning on. The AFS light is on on the back of the board.

Here's the thing, I am not sure if propane is actually getting to the heater from the propane tank tank. (usually when I turn the valve at the heater i can feel the pressure of the gas moving in the pipes)

My question is, if propane wasn't getting to the heater would it cause the click no fire and no blower turning on and lighting the AFS light?

Any help is appreciated

thanks
henry
 
The AFS LED is due to the blower not turning on.

The heater won't even try to fire if it doesn't sense the AFS closing.

You need to figure out why the blower isn't coming on.

Here is a thread about testing the blower.

Mastertemp 400 humming (already replaced the "run" cap) still humming

Hi my tfp friends I have a Mastertemp 400 and its blower humm when pool or spa are turned on (humms like a pump motor with a failed cap), and "service heater" led turns on, i already replaced the cap (8uF-250vac), but still the same failure. Problem starts when working (last weekeend) there...
www.troublefreepool.com www.troublefreepool.com

Can you show a video of the heater startup and attempt to ignite?

Are all of the gas valves On?

Is the gas valve in the heater switched to On?
 
JamesW said:
The AFS LED is due to the blower not turning on.

The heater won't even try to fire if it doesn't sense the AFS closing.

You need to figure out why the blower isn't coming on.

Here is a thread about testing the blower.

Mastertemp 400 humming (already replaced the "run" cap) still humming

Hi my tfp friends I have a Mastertemp 400 and its blower humm when pool or spa are turned on (humms like a pump motor with a failed cap), and "service heater" led turns on, i already replaced the cap (8uF-250vac), but still the same failure. Problem starts when working (last weekeend) there...
www.troublefreepool.com www.troublefreepool.com
Click to expand...
if there is no propane going into the heater, would this cause the blower not to come on?
 
Henry121083 said:
I am having a similar problem (minus the rodents) It seems like you're the expert on heaters.

Mine is clicking but no ignition and no blower. I am not sure gas is getting into the heater - would this happen if gas wasn't getting in? (maybe bad regulator at tank or something)
Click to expand...

No, read the sequence of operation in Pentair MasterTemp Heaters - Further Reading

You need blower first before ignition sequence then gas for flame.
 
Last edited:
JamesW said:
The AFS LED is due to the blower not turning on.

The heater won't even try to fire if it doesn't sense the AFS closing.

You need to figure out why the blower isn't coming on.

Here is a thread about testing the blower.

Mastertemp 400 humming (already replaced the "run" cap) still humming

Hi my tfp friends I have a Mastertemp 400 and its blower humm when pool or spa are turned on (humms like a pump motor with a failed cap), and "service heater" led turns on, i already replaced the cap (8uF-250vac), but still the same failure. Problem starts when working (last weekeend) there...
www.troublefreepool.com www.troublefreepool.com

Can you show a video of the heater startup and attempt to ignite?

Are all of the gas valves On?

Is the gas valve in the heater switched to On?
Click to expand...

It doesn't attempt to ignite. I get a click and then nothing. All gas valves are on. Gas valve in the heater is on.

I took the two blue leads off the AFS and touched them together. The AFS light on the board goes out and the blower kicked on for a bit (it's hard to keep the connectors together)
 
Check the resistance of the AFS switch.

It should be open before the blower starts and closed after the blower starts.

Do this with the AFS switch wires off and not connected together.
 
JamesW said:
Check the resistance of the AFS switch.

It should be open before the blower starts and closed after the blower starts.

Do this with the AFS switch wires off and not connected together.
Click to expand...

here is a video of when i jump the wires-
it seems like it kicks on - not sure if that's the way it's supposed to be.

I am a terrible electrician (i'm not one at all) so i think i checked resistance right - the needle didn't even move
(video here) when i touched the two contacts together needle went all the way to the right
 

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I can't tell what's happening in the second video.

With the wires removed from the airflow switch and the wires not connected together, measure the resistance from one terminal of the airflow switch to the other terminal.

Before the blower starts, the contacts should show as open.

Once the blower starts, the contacts should show as closed.

The blower sounds odd.

You can use some of the test procedures as described in the referenced thread if you feel comfortable doing that.
 
JamesW said:
I can't tell what's happening in the second video.

With the wires removed from the airflow switch and the wires not connected together, measure the resistance from one terminal of the airflow switch to the other terminal.

Before the blower starts, the contacts should show as open.

Once the blower starts, the contacts should show as closed.

The blower sounds odd.

You can use some of the test procedures as described in the referenced thread if you feel comfortable doing that.
Click to expand...

With the wires removed from the airflow switch and the wires not connected together, measure the resistance from one terminal of the airflow switch to the other terminal. - That was the second video - the needle did not move at all. it stayed all the way over to the left
 
It looks like the blower is not running full speed.

I would check the capacitor on the motor. It's under the hump on the motor.

You can also do some of the other motor tests as described in the referenced thread.
 
JamesW said:
I can't tell what's happening in the second video.

With the wires removed from the airflow switch and the wires not connected together, measure the resistance from one terminal of the airflow switch to the other terminal.

Before the blower starts, the contacts should show as open.

Once the blower starts, the contacts should show as closed.

The blower sounds odd.

You can use some of the test procedures as described in the referenced thread if you feel comfortable doing that.
Click to expand...

never mind on this. I took the panel off to check the Ignition Control Module and there was a big mouse nest and a few critters back there. They chewed the wires and made a mess. I'm going to have to call an expert to come in and fix it
 
JamesW said:
Ok. Thanks for the update.

Post a picture if you want us to check the damage.
Click to expand...

it was so sunny I didnt best I could with the sunlight -

This has happened once before and I think the previous repair guy used those splices

let me know what you think - anything glaring about why the blower wouldn't kick on? I tried looking at the wiring diagram to figure it out but no dice
 
JamesW said:
Hard to tell. Hopefully, it will work once all the wires are replaced.
Click to expand...
the diagnostic led on the module flashes once which according to the manual indicates "air flow fault"

What can I do to check that? The wires although frayed look like they're making contact - i'm wondering if this "air flow fault" is the issue and not the wiring?
 
If the blower is not running correctly, then you're going to have an air flow fault.

I would figure out why the blower isn't running correctly.

Go through the blower test procedures and check the capacitor.

Don't run the heater with damaged wires. Something can short out or spark, which is not safe with a gas heater.
 

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