Another.....Mastertemp 400 with AGS LED + Service Heater LED

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This is the manual for your heater http://www.pentairpoolme.com/uploads/document/file/554/Manual_MasterTemp.pdf . Pay attention to pages 31 and 32 the connection and ladder diagrams. You will notice that all of the safeties and gas valve are run through the operating control and ignition module. You should first have 24 volts ungrounded to IND on the ignition module through water pressure switch and hi limit to start the inducer (blower) motor which will then make the air flow switch to put 24 volts ungrounded to the TH (W on some) terminal on the ignition module. This should start the ignition trial. After the ignitor warm up time the ignition module powers the gas valve through VAL on the ignition module, but this also goes through the operating control VAL which then goes through the AGS safety to the gas valve. This is your ignition module
Fenwal 35-662944-013 and it is user specifically modified which is why you don't see a W terminal. You should notice on the ladder diagram that one leg of the 24 volt side is grounded. Right after the heater fires up, if you add a jumper from the ignition module VAL terminal to the TH terminal on the gas valve and the heater keeps firing then the problem is either with the AGS switch or the operating control. If it still shuts down then the problem is with flame sensing.
 
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swamprat69 said:
This is the manual for your heater http://www.pentairpoolme.com/uploads/document/file/554/Manual_MasterTemp.pdf . Pay attention to pages 31 and 32 the connection and ladder diagrams. You will notice that all of the safeties and gas valve are run through the operating control and ignition module. You should first have 24 volts ungrounded to IND on the ignition module through water pressure switch and hi limit to start the inducer (blower) motor which will then make the air flow switch to put 24 volts ungrounded to the TH (W on some) terminal on the ignition module. This should start the ignition trial. After the ignitor warm up time the ignition module powers the gas valve through VAL on the ignition module, but this also goes through the operating control VAL which then goes through the AGS safety to the gas valve. This is your ignition module
Fenwal 35-662944-013 and it is user specifically modified which is why you don't see a W terminal. You should notice on the ladder diagram that one leg of the 24 volt side is grounded. Right after the heater fires up, if you add a jumper from the ignition module VAL terminal to the TH terminal on the gas valve and the heater keeps firing then the problem is either with the AGS switch or the operating control. If it still shuts down then the problem is with flame sensing.
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Thanks!
 
swamprat69 said:
This is the manual for your heater http://www.pentairpoolme.com/uploads/document/file/554/Manual_MasterTemp.pdf . Pay attention to pages 31 and 32 the connection and ladder diagrams. You will notice that all of the safeties and gas valve are run through the operating control and ignition module. You should first have 24 volts ungrounded to IND on the ignition module through water pressure switch and hi limit to start the inducer (blower) motor which will then make the air flow switch to put 24 volts ungrounded to the TH (W on some) terminal on the ignition module. This should start the ignition trial. After the ignitor warm up time the ignition module powers the gas valve through VAL on the ignition module, but this also goes through the operating control VAL which then goes through the AGS safety to the gas valve. This is your ignition module
Fenwal 35-662944-013 and it is user specifically modified which is why you don't see a W terminal. You should notice on the ladder diagram that one leg of the 24 volt side is grounded. Right after the heater fires up, if you add a jumper from the ignition module VAL terminal to the TH terminal on the gas valve and the heater keeps firing then the problem is either with the AGS switch or the operating control. If it still shuts down then the problem is with flame sensing.
Click to expand...
This is great info! In fact I have taken a gander at that ladder diagram more than once. Since it's winter and I have no immediate need for heat, I'm going to go through your info and apply some voltage tests. I'll come back here if I have any further questions.
 
The heater is shutting down because it is reading the AGS circuit as open.

That's clear from the AGS light coming on.

Since the AGS circuit is definitely closed, that means that the board is reading the circuit incorrectly.
 
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JamesW said:
The heater is shutting down because it is reading the AGS circuit as open.

That's clear from the AGS light coming on.

Since the AGS circuit is definitely closed, that means that the board is reading the circuit incorrectly.
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@JamesW Ya I'm with ya on this. Ok so I double checked your theory just now. You can watch my video to verify I did this correctly?


Verified hypothesis by jumpering(together) the AGS lead wires while being disconnected from the AGS sensor. Started the heater. Then checked continuity on the AGS sensor prongs. (in the video I said wires, OOPS).

Checked sensor to see if the circuit opens ....which it NOT.

Remaining closed and the AGS light is illuminated on the board, tells us the board "thinks" the curcuit is open and hence the board is bad.
 
Just curious as to why the service heater light comes on and then the heater fires up. To confirm that you don't have more than one problem I would do this. Right after the heater fires up, if you add a jumper from the ignition module VAL terminal to the TH terminal on the gas valve and the heater keeps firing then the problem is either with the AGS switch or the operating control. If it still shuts down then the problem is with flame sensing. You can pull the VAL connector on the ignition module halfway off to add the jumper to the TH terminal on the gas valve. Will be away for the holidays and not able to reply for a couple weeks. With the jumper you will be bypassing both the main controller and the AGS switch.
 
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Just trying to isolate and eliminate possibilities. If controller is truly not reading the AGS switch it could be wiring continuity, pin/socket corrosion, pin pushed back in connector so it isn't making contact or cracked trace on the controller circuit board. Also, if there is a problem with the controller reading the AGS switch how does the heater fire in the first place since the AGS switch and controller circuit board are in series with the gas valve?
 
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Read the Ladder diagram on pg. 32 and you can see that the AGS switch is in series with the gas valve. The AGS switch is in series with the gas valve through the controller circuit board and the pin connections on the left hand side of the controller circuit board. In the connection diagram 24 volts out from VAL on the ignition control goes to VAL on the controller circuit board and then through the AGS switch to TH on the gas valve. The other safeties are in series with IND (inducer relay) and the TH (call for heat or [W]) on the ignition module
 
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