"Main to one side", I don't quite understand.  Are you connecting one lead to the black supply terminal and the other to one side of the heater and then to the other?

Check that on the supply terminal block you are getting 240 v, black to red terminals.  If this is so, and based on what you just described it indicated that the relay contact that connects the Black AC side to the heater element, isn't closing, to complete the circuit to the heater element.  One end of the heater, left side, is made live as soon as the power is applied to the circuit board, but the other sides connection is not completed to black AC until the heat LED is on steady.

I will wait for your reply, but so far it looks like a relay fault, in which case the circuit board gets replaced.  The fact you get the temperature up to 95 degrees, is due to heat provided by the pump.

Dieter

Yes you have interpreted my weak electrical terminalogy. Now what? Is it easy to replace the circuit board? Last time I replaced the whole Spa Pak. My tub has no pump isolation shut off valves. I must drain tub to remove Pak. With this cold weather I do not want to empty tub and leave it sit while I wait for new board. Pak is a Balboa Revolution BP 1500.  

Gord

Yes you have interpreted my weak electrical terminalogy. Now what? Is it easy to replace the circuit board? Last time I replaced the whole Spa Pak. My tub has no pump isolation shut off valves. I must drain tub to remove Pak. With this cold weather I do not want to empty tub and leave it sit while I wait for new board. Pak is a Balboa Revolution BP 1500.  

Gord

That one (the BP1500) is tougher to replace parts out of.  It is not a single board but two and the lower one likely is the culprit that needs replacement.  For this reason technicians usually prefer to replace the entire spa pack but Balboa, in their warranty terms, only covers the actual part that is faulty.

If you don't want to drain the water then you need to replace the board(s).  While it is not difficult for me, you do have to figure out how to do it.  First you unplug everything, then take out the top logic board.  Then you can remove the larger bottom relay board.

However to get a replacement under warranty, I will need the Invoice # under which you obtained the BP1500 from us.  Then I also need the serial # of the spa pack (found on the outside of the case), as well as the serial # of the main relay board (found on a white label stuck to the board).  Then I can proceed to make a claim with Balboa.

Dieter

Purchased Pak on June 7. #10416.  Model NXG 12-4.0 Pak #5569***1210250015. Board #BP1500R1C 20121025. I will wait for board before removing Pak. Clearance is tight. Will have to remove pak. I had a tough time removing lid. Very tight.                                                                    Gord

Purchased Pak on June 7. #10416.  Model NXG 12-4.0 Pak #5569***1210250015. Board #BP1500R1C 20121025. I will wait for board before removing Pak. Clearance is tight. Will have to remove pak. I had a tough time removing lid. Very tight.                                                                    Gord