My 425 fan failed!!

jol1269 · May 14, 2005

hey bob , i havent had a failure yet on my fan but do you have a way of taking anypics of the switch and fuse you have there so i can see if i should expect the same issue so i might stop an issue before i have one if it is of the same type as yours . i have a 425 so im not sure if they are or not

BobRip · May 15, 2005

Here are the failing items. The temp switch is on the left and the fuse holder is on the right.

Bob999 · May 16, 2005

I think the switch you are looking for is commonly used in HVAC applications. Here is a link to MSC supply that has a range of products. MSC

BobRip · May 16, 2005

That looks very similar to it and would most likely work. I already ordered one from PT today. It was about $22 plus shipping.

Thanks for the link.

BobRip

tracdoc · May 17, 2005

The MSC units are spec'd as AC, for 120/240 V AC applications. Would they work in the 12V DC world of the PT, or more likely, would we need a DC circuit unit?

BobRip · May 17, 2005

They will work, but you need to get a current rating at 12 vdc. It did not have one on the link. I suspect that the early failure of my 422 temperature switch could be caused by using an AC switch on a DC circuit. The nice thing about AC (when switching) is that the current turns off 120 times a second. This creates less arcing of the contacts and less wear on the switch. My 422 has about 400 hours on it, so I am not particularly concerned about replaced a switch every 4 or 5 years. By the way, I received the switch today and it cost $25.57 including shipping. It took less than 10 minutes to install. Of course the fan will probably go next.

Bob Rip

Robert259 · May 18, 2005

I agree. Using ac rated contacts on a dc circuit will cause premature failure of the contacts.

Bob999 · May 18, 2005

<font color="red">Using ac rated contacts on a dc circuit will cause premature failure of the contacts.
</font>

I wonder if the switch PT uses is DC rated.

BobRip · May 18, 2005

Most AC switches will handle a DC load, but at a lower voltage and current. You may have to question the switch manufacturer to get this kind of information. I guess that my switch operated about 400 times over 400 hours of machine operation. This seems kind of short. I just consider it part of routine maintenance to replace it. If necessary I could add a dc rated relay driven by the temperature switch.

Bob Rip

davesisk · May 20, 2005

Just noticed this thread. The temp switch on my fan didn't work when I got the machine. I decided to wire the fan directly to the ignition switch so that it stays on whenever the switch is on. I believe I probably used the accesory pin on the ignition switch? You can test it with a meter and make sure it has a voltage when the switch is in the on position and not voltage when it's off...I don't believe the fan draws any significant current. This seemed like a pretty good mod to make, especially since heat is the dire enemy of all things hydraulic.

Dave