Update-
A couple days ago the fan started coming on as soon as I turned the key. I sent a message privately to the seller no reply. I checked the manual switch I added by removing its ground and it still came on with that disconnected. That was in question because the vid I saw said it needed to be higher rated than it is. It is a cheap one from Home Despot. It went off when I removed the wire from the temp switch. I sent another message no response. It was over 100 here for a few days so I waited until this morning. It was cold to the touch and it still came on with the key. Conclusion the fail safe is that the switch goes to ground when it fails so that the fan stays on. Today I contacted the seller via the site direct from the page the item is sold from. They responded a couple hours later that a new switch was on its way.
I drove it today with that wire disconnected and when I remembered to look it was close to H. I hit the manual switch and it cooled down to normal in less than 5 minutes. It is very loud I may change it over to using the low speed side.

 

It never ends.

 

Update- American Volt is not responding.
I had sent the first message telling them the temp switch failed via the purchase of another kit w/o hose adapter that I purchased for my other vehicle. They responded "replacement on the way" It never arrived. When I checked eBay messaging I saw my mistake and sent the message from the correct purchase with an explanation. No reply. Waited a few weeks and sent another message and also sent same message via their website form.
They have not responded at all since that first message. The grounding temp switch they sent me 210-195, died in less than 2 months.
I have the complaint written and waiting until some time tomorrow to file it with eBay. IDK what to ask for beyond a working switch since removing the kit to send it back will disable my truck or force me to undo all the work I did to put in an electric fan.

 

Well I dealt with eBay for a frustrating couple hours by chat that week. They had me send another message to the seller. Still ghosting me. So today I fought with the computer assistant for another 20 minutes before I could get someone on the chat. They said I had no case with eBay because of the 30 day limit, it went defective after 30 days. Then told me how to get a refund. Gave me a phone number and instructions to contact PayPal. The first round the computer hung up by me being nice and answering it. Second round I just told it to give me a person and it did! Case filed. He said 7-10 days. That only took about 10 minutes! Another shock. The eBay guy seemed to think 4 weeks was about the average. Anyway maybe they will finally send me the part instead of giving back the money? The part that really ticks me off is the "replacement on the way" reply to my initial message then, nothing but ghosts. The other one seems to be working just fine but I drive it less.

Edit- It was too good to be true. The idiot filed for a refund for the wrong purchase! I gave him the info eBay told me too. When I called back I got the run around and they added in some "expectation management" by telling me about some 30 day limit no one ever mentioned before.

 

update- I never got a response from the seller of the kit and both ebay and paypal denied my claim.
If the readings on my dash are correct and the sensors are pretty new, the motor never heated up past halfway on the guage. I suspect the breaker in the kit was tripped and that may be why the fan was continuously on. But IDK. When I reconnected the wire to the sensor several weeks later it did not kick on when the key was on and the dash guage never indicated high temps.

Now this is just a theory since the seller never replied to me to discuss what might be going wrong - We had a very hot period this summer and with the temp sensor being in the radiator tube coming out of the thermostat housing going to the top radiator hose connection right up close to the hood it got overheated by the sun beating down on it and that tripped the breaker making the fan run continuously when I turned the key on. If it happens again I will try insulating the adapter that holds the temp sensor to protect it from being heated up by the sun.

So if you know a better way than this one do that. Otherwise I think my trick of putting the fan inside the OE shroud is pretty good for handling the switch from manual to electric.