Pentair MiniMax Plus 400 not firing

[AustroTom]

Hello All,
Wanted to get the kids in the hot tub two nights ago and discovered the heater wouldn't fire.
The lights are all on except heat and the service light is on as well. The pilot wants to fire (klicking noise for several seconds), but no gas flowing.
The troubleshoot guide shows "blown thermal fuse blocks firing".
Is that something I can fix/ replace myself or do I have to call a service technician.
Help greatly appreciated.
Thank you,
Thomas

 

[Arizonarob]

Hi Tom, hang tight and I’ll ping one of our heater gurus. @JamesW

 

[AustroTom]

Hi Tom, hang tight and I’ll ping one of our heater gurus. @JamesW

Thank you

 

[AustroTom]

Anybody out there that can help me with this?
Thank you
Thomas

 

[Arizonarob]

Not sure where @JamesW is, might be on vacation.

 

[JamesW]

I don't really know that heater too well.

 

[Arizonarob]

Thanks James. Let me try a few others that may be able to help. @pooldv @mas985 @triptyx @bobodaclown

 

[pooldv]

Swing and a miss for me as well. Maybe Paul can help, @ps0303

 

[kadavis]

First of all if the thermal fuse was bad you wouldn't have a spark, and the service light stays on until pilot lites. You could have a block in the pilot orifice, or no voltage going to the PV terminal on the gas valve. There's a manual with a troubleshooting guide,Pentair MiniMax Plus Service Manual (Page 28 of 36)

 

[AustroTom]

Thank you so much, guys.
This ts guide is awesome! I will go to work this weekend checking all of the possible causes.
Thomas

 

[triptyx]

When's the last time you replaced the flow meter? My heater is a lot older than yours so I don't have any codes to read, but it was having trouble at times lighting (would click forever and finally light - eventually it stopped lighting altogether and would just click). Replacing a $60 flow meter took care of it. I wasn't able to get it out myself (it was frozen into the socket) so I had to hire someone, but if it hadn't been frozen in place it was a simple fix.

I believe you can troubleshoot this by bypassing the flow meter for a moment to see if the heater lights.

 

[ps0303]

If you had a blown thermal fuse the unit would never try to fire. The clicking noise is a short in the control board or a bad ignition module.

 

[AustroTom]

It's actually not really a clicking but rather a sort of rapid fire "TRRRRRRRRRRRRRRRRRRRRRRRR", and it goes on for at least 20 seconds until it turns off and the red service light comes on and stays on.

 

[AustroTom]

Hello All,
So I tried the POWER/T-STAT/AUX/PRESS/SERVICE NO SPARK troubleshooting (pg. 27), and when it stopped clicking the Pilot valve light on the back of circuit board went out. I DO have 24v at the orange wire.

Any thoughts? Bad Module?

 

[ps0303]

Remove and open the ignition control module and see if the board looks good. As mentioned earlier, it's usually the control module or the actual system board causing the ignitor to act like this. Usually a visual inspection of the two boards will reveal the issue.

 

[AustroTom]

Ok. Took it out, opened it and it doesn't look damage or anything. But then again, I'm not an expert by a long shot

 

[AustroTom]

so I ordered a new module but it didn't fix the problem. So i'm thinking of taking apart the gas valve?

 

[AustroTom]

Would anybody know how to test the Pentair 460761 Propane Gas Valve?

Help greatly apreciated

 

[Rocco]

I have an old heater similar to this and I get this same thing every year after opening. I have to remove the burner assembly and clean it. The reason is that it the small holes get clogged with dirt and there is not enough gas flow. Once I clean and reassemble the unit fires without any issues.

 

[AustroTom]

makes sense. Although DID already clean the pilot pipe. The electric spark ignitor does klick (for about 60 seconds but I don't see a spark