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Pentair indoor pool/spa controller shows "---" instead of temperature

Pentair indoor pool/spa controller shows "---" instead of temperature

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  #1  
Old 10-16-15, 12:34 PM
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Pentair indoor pool/spa controller shows "---" instead of temperature

My pool/spa system includes a Pentair PC-CP100 indoor controller. This allows me to turn the pool lights and spa on and off from indoors.

It has a 3-digit LED display which shows the water temperature in the spa. It has always been a little flaky. Most of the time it shows the right temperature, but often goes crazy and shows temperatures like 27 degrees or -35 degrees.

Now, finally, it shows only "---" where the temperature should be.

I have traced and checked as much of the wiring as I could and found no shorts or opens. This unit was here when I bought the house, so I don't really know all its secrets.

Does any one know the secrets of this unit, and how I might proceed to troubleshoot? Thanks!

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  #2  
Old 10-16-15, 06:09 PM
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That system uses 2) cables for communicating. After the wire is installed modular plugs are crimped on to each end. That would be the most likely place for problems.

You've said that the temperature indicator is out now and was erratic... how about the switches and their respective indicators ?

Your manual... which in this case is just about useless.
http://www.pentairpool.com/pdfs/CP-100CntrlSysIG.pdf
 
  #3  
Old 10-16-15, 10:29 PM
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Thanks for the reply. I should have mentioned that everything else works, and always has, despite the erratic temperature display.

The controller's pushbuttons and their respective indicators all function correctly. The LCD temperature display outdoors on the pool/spa heater itself reads correctly, and I assume that uses the same temp sensor as the indoor readout.

I did examine (and jiggle, extract, and re-insert) all 4 modular plugs at both ends of the cables and they seem OK. The outdoor ends show no signs of weather intrusion and neither ends have never been touched.

I opened up the indoor and outdoor controllers and eyeballed them without seeing anything obviously amiss.

I have the paper installation/user manual. It's not helpful and it doesn't say anything about what would cause the "---" display.

At this point I guess it points to a bad connection on the input cable even though both ends look OK by eye (since the output cable successfully controls the valve & lights). Any further thoughts?
 
  #4  
Old 10-16-15, 10:37 PM
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Take all four ends out..... use an old toothbrush and some rubbing or isopropyl alcohol and clean the pins on the modular cables. Give them an hour to dry and try them again.

If that didn't help I'd consider recrimping the ends.
 
  #5  
Old 10-17-15, 03:22 PM
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Well, today the indicator is back to showing oddball temps like -63 degrees.

I cleaned the pins but it didn't help. That was a good idea, though.

I'm starting to suspect the circuit board inside the indoor controller. I may take it out and look for bad solder joints. Naturally, this board is a discontinued part.
 
  #6  
Old 10-18-15, 01:56 PM
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Actually.. it may be available but looks to be over $200.
 
  #7  
Old 10-18-15, 03:52 PM
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Q: What is a swimming pool?
A: A big hole in the ground you pour money into.

I think I'll pull both indoor & outdoor PC boards and eyeball them. A failure is more likely in the outdoor board, but I'll start with the indoor one because it's easier.
 
  #8  
Old 10-18-15, 04:41 PM
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Q: What is a swimming pool?
A: A big hole in the ground you pour money into.
I know. I have a 40+ year old 20'x40' inground Sylvan cement pool.
 
  #9  
Old 10-18-15, 05:40 PM
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My pool is about the same size, with a ~9' deep end for diving board. Being in drought-stricken CA, I'm glad I don't have to drain ~41,000 gallons for winter. And thankful for the motorized pool cover to prevent evaporation.
 
  #10  
Old 10-18-15, 06:13 PM
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I also have a 9' deep end for the diving board although the old board rotted away and I never replaced it. That sounds like a lot of water. I've estimated mine to be +/- 25,000 gallons.
 
  #11  
Old 05-27-17, 03:46 PM
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SOLVED: Pentair indoor pool/spa controller shows "---" instead of temperature

OP here, almost 2 years later.

I'm happy to report I finally solved the problem of the incorrect pool temperature display, with the help of the Internets & YouTube videos.

This wasn't nearly as complicated as I tried to make it. The culprit was simply the water temperature sensor itself. This is an external probe which is inserted into a hole drilled in the incoming water pipe and held in place with a pipe clamp.

These are model-specific. TS5L is the required model for the Compool controllers.

$45 from Amazon and we are happy swimmers once again.
 

Last edited by RocketJSquirrel; 05-27-17 at 03:47 PM. Reason: typo
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