Jandy LT400

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Hollywood151

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Jul 23, 2015
9
Fairport
Good morning

So down to it, the problem that is!

I just purchased a used Jandy LT400 from a friend. I have it plumbed and wired...

When I first turned it on, it went through diagnostic, then threw a pressure switch light... so I replaced it.

Tried again...still have the pressure light flashing... so I turned down the thermostat on the pool side...and the light stayed off. As I turned the knob towards the red, there was a small click, and the light came on and started flashing. I repeated this process multiple times...

Could use some help here... Thanks so much in advance!

James
 
The pressure switch light does not indicate that it is bad. It indicates that the pump pressure is not sufficient to close the contacts and allow the heater to fire. You may need to use a higher speed on the pump if possible to get the switch to close.
 
Filter basket is spotless...well, not spotless...its old...old things have spots...Im old, I have spots...

I just replaced the motor, its a 53J (I think) 1HP motor...

Flow through the copper tubing is strong, its got to be more that 2psi... No?

danpik said:
The pressure switch light does not indicate that it is bad. It indicates that the pump pressure is not sufficient to close the contacts and allow the heater to fire. You may need to use a higher speed on the pump if possible to get the switch to close.
Click to expand...
 
With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
 
Thanks for that, will do that and post the numbers. It will have to wait until a bit later, new liner is being installed as we speak/type/whatever...

danpik said:
With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
Click to expand...
 
Is the service light coming on? Is there any type of automation on this system? If so, This is a normal display when a device connected to the “Fireman Switch” operates to open the safety circuit on the heater.
 
.02 Ohms with one wire detached. Its very odd, the pressure switch light doesnt come on, until I turn up the temperature knob. It does it at the same place every time.

danpik said:
With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
Click to expand...
 

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Hollywood151 said:
.02 Ohms with one wire detached. Its very odd, the pressure switch light doesnt come on, until I turn up the temperature knob. It does it at the same place every time.
Click to expand...
That is almost no resistance so I would say the pressure switch is closing. Does the resistance change when you cut the pump off? It should go up high or show the infinity symbol on the screen (or what ever the meter shows for open circuit)
 
I do not know, but my assumption is no. It was a pretty clean disconnect. Safety loop is in place and there are no extra wires nor any connections missing.
ps0303 said:
You say you purchased it used. Do you know if the previous owner had it hooked into any type of automation system?
Click to expand...

- - - Updated - - -

It does change when the pump is turned off.

Anyone need an LT400 for parts? I'm frustrated, I cant seem to find another occurance where turning up the temperature knob makes the pressure switch light come on.

danpik said:
That is almost no resistance so I would say the pressure switch is closing. Does the resistance change when you cut the pump off? It should go up high or show the infinity symbol on the screen (or what ever the meter shows for open circuit)
Click to expand...
 
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