Pentair IC40 Cell light flashing green

johnnybravojr

Member
Sep 17, 2021
15
Michigan
I know there's a high chance that the cell is dead but it is currently hard/very expensive to find a new one so I wanted to see if there are any troubleshooting options left. A couple of days ago, my saltwater pool became cloudy. The cell light flashes green (but salt and all other indicators are good on the IC40). Opened up the IC40 and it appears to be clean (no calcium buildup that I could see). Put it back together and started the pump. After about 5 minutes or so the cell light flashes green again. I did the diagnostic mode, and I should have 60% life left (the 40% was illuminated) even though the unit is 5 years old. I pressed mode again, and noticed the temp reading is roughly 10 degrees higher than the thermometer is reading from the pool (not sure if this means the thermistor is bad). Also, when in diagnostic mode, the LOW stayed red. When leaving the mode and back to normal, it cleared.

I ordered some test strips to check the phosphate levels (won't arrive till tomorrow). And I have a salt tester that reports almost 4000 PPM (which seems high) so the tester could be bad but the IC40 doesn't complain about low salt so I wasn't worried about it. When we opened the pool (a month ago), it was reading low salt which made me put too much salt in so I back washed the filter to remove some (adding in fresh water with a hose). I'm hoping that maybe the thermistor was going bad which is why we had the low salt issue at beginning of the season and potentially why the cell light is flashing. I'm not sure if 10 degrees off is a big deal or not though.

Any other ideas or things I can try? Thanks!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
50,889
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Sadly, if the Cell light flashes Green, and the cell is clean of calcium scale buildup, the cell is dead.

Let's ask @Jimrahbe to confirm.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
27,131
Bedford, TX
Johnny,

If the cell is clean and the cell light is flashing, it usually means the cell is dead. Most cells last 5 to 7 years.

Since the only option is to buy a new one, you can't hurt it, by try things.

I suggest that you cut the Green wire between the Flow Switch and the Cell itself. This will remove the external thermistor that is in the Flow Switch.

I say this as you seem to believe that the current thermistor is bad. Again, it can't hurt to try.

I have had two cells go bad and they both had the identical symptoms your cell is having.

Thanks,

Jim R.
 

johnnybravojr

Member
Sep 17, 2021
15
Michigan
Thank you for your response! I will try that and get back to you. Just to understand, if I cut the wire and the cell light stays green, then I can replace the flow sensor (which has the thermistor built-in)? Does doing this bypass if the phosphate level is high?
 

jeffchap

Bronze Supporter
TFP Guide
Jun 26, 2012
2,385
Edmond OK
Pool Size
27500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
AFAIK, phosphates have no impact on the operation of an SWG.

If yours is indeed dead, I replaced my IC40 last month with one of these and I'm completely satisfied. I've actually had to dial it down 50% - it makes more chlorine than my IC40 did.

 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
27,131
Bedford, TX
Johnny,

Just so that we are both on the same page.

The cell light is normally only green when the cell is making chlorine. At 50% output, the cell light will be on solid green for 2.5 minutes and then off for 2.5 minutes. The cell light flashes when it thinks the cell is dirty with scale. If the cell is clean and the light flashes, it normally means the cell is dead.

If you cut the green wire and the light no longer flashes, I would not get too excited until it has run a day or so with no issues. I doubt this will happen, but let's hope it does. If the cell runs ok after the wire has been cut, then I would install a new flow switch.

Thanks,

Jim R.
 

ImpalaSS

Well-known member
May 5, 2020
136
Southern Maryland
AFAIK, phosphates have no impact on the operation of an SWG.

If yours is indeed dead, I replaced my IC40 last month with one of these and I'm completely satisfied. I've actually had to dial it down 50% - it makes more chlorine than my IC40 did.


Those things have pretty good reviews.
 

johnnybravojr

Member
Sep 17, 2021
15
Michigan
Thank you everyone for all the feedback. Just to update. I cut the green wire, and now the cell light still flashes green and I get a green flash on the high salt indicator. I'm assuming this confirms the cell is bad. I will check out the generic option as well as another IC40 (man they got expensive during COVID).
 
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