Strange cooling problem with STT8300

My STT8300 has developed a strange cooling problem. It first appeared when I connected to the camera with MaxImDL. MaxImDL reported 100% cooling power over some minutes but did not cool the camera down from ambient temperature. I was getting frustrated because the camera had been returned for repair in 2016 for a cooler problem (open circuit I think it was). So my first thought was "Not again!"

However, while swapping things in and out to try to identify the cause, I discovered that if I connected the camera first through the Camera Add On of TheSkyX, the camera began to cool normally. If I then swapped it back to MaxImDL, the cooling continued to work OK. I have tried this several times over a number of days and the same symptoms appear.

I regularly use the SBIGDriveChecker64 (version 4.03 Build 1 64 bit) to check for, and if necessary, install updated drivers. The DriveChecker also tells me I have the latest firmware for the camera. Yet if the camera goes into cooling mode properly with one software and not the other, do I have a driver problem? Is there a way to fix this?

 

Thanks for your suggestions. After persisting for some days, the problem seems to have resolved itself. However, I am none the wiser for its cause. I did/do in fact have an extension of the power cord, but not a very long one. I have changed to a regulated power supply able to supply 13.8 volts and up to 35 amps peak (25 amps 50% duty cycle). That's no doubt overkill regards the amps, but … am I pushing things too much with 13.8 volts? I see the manual gives a range of volts up to 14 volts, but I'd like to be sure I am on the safe side.