Incorrect temp reading on Jandy LX heater...HELP!

[mojo jojo]

Hi,
I have a 12 year old Jandy LX heater and have had very good luck with it until recently. When I fired it up for the first time this year, the temperature reading was 84 degrees Fahrenheit. I could tell it was wrong by putting my foot in the pool so I checked the floating thermometer and it read closer to 60 degrees.
I cranked the desired setting to 104 (that's as high as it will go) and although the heater seemed to work fine, my pool is now around 75 and I can't get it any warmer because the thermometer still reads 104.
I like it around 85 degrees.

Have any of you experienced this issue? Any help would be appreciated.

 

[LI poolguy]

Could be a bad temp sensor in the heater.

 

[mojo jojo]

Could be a bad temp sensor in the heater.

Is there a way I can test it with my digital multimeter or is it one of those things you just have to swap out and see?

 

[JamesW]

Check resistance of thermistor. It should follow the resistance given by a 10k thermistor chart.

 

[Pool Clown]

Hope this helps...

Temp sensor P/N: R0011800

 

[mojo jojo]

Great info, thanks very much to all. I'll let you know how it works out later this week when
I've had a chance to dig in to this.

 

[mojo jojo]

I finally got around to this and am reading 10.2 k Ohms from the disconnected sensor, which is probably pretty close. But when I reconnect it to the control PCB, the display reads 85 degrees and rapidly climbs to 111.

Hope this helps...

Temp sensor P/N: R0011800

 

[ps0303]

Is the heater running/flames on, when it jumps to 111? If so then it sounds like a water flow or bypass issue. If it's jumping to 111 and you don't have any flames burning, then it could be a bad temperature control.

 

[mojo jojo]

it does this without any flame at all. Do you think this is the part I need?

http://www.parts4heating.com/Jandy-7417G-Temperature-Control-w-Bezel-LX-only-p/7417g.htm

 

[mojo jojo]

Could be a bad temp sensor in the heater.

Well, it turned out to be a bad temp sensor after all. It metered out okay, so that threw me, but I figured it was worth replacing for $70 before I went all in on a new control board.

Thanks to all for your input.