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

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


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

BobRip · May 20, 2005

The fan pulls about 4 amps on my 422. Not major, but significant on a 15 amp maximum output alternator. It also increase hydraulic fluid warm up time. Fluids don't lubricate as well when they are cold, so wear increases. I am sure PT would not put a switch in there if it is not needed. It's your machine, but it will run longer if everything works right.
Just my opinion.

Bob Rip

MossRoad · May 20, 2005

While I agree that the fan should work, it seems that my fan doesn't come on for about 20 minutes in 70 degree weather while mowing. Then is stays on forever. It never shuts off, no matter what I do. So I assume that it never cools down the system to below the thermostat low setting. Even does the same thing in the winter. Once it comes on, it never shuts off.

BobRip · May 20, 2005

Mine works the same. I have never seen it cutoff once the system warms up. It's that first few minutes to allow quick warm up that is important to let the oil get up to a good lubricating temperature and I believe is the main function of the switch. It is probably more important in the winter than summer.
Bob Rip

J_J · May 20, 2005

Your system seems to be operating like it should. Consider this, it will take a while to warm up 10 gal of hyd fluid, and once hot, that little cooler and fan would never keep up with the heat generated. I think the only purpose of the fan and cooler is to keep it from getting too hot. Even when you shut off the unit, that hyd fluid will take hours to cool down.

Does anyones fan cycle on and off.?

Next best thing would be to install an over temp switch in the hyd circuit , which would sound a buzzer, or flashing light

FOURTEEN · May 21, 2005

( Just noticed this thread. ) 

 To avoid missing any threads:

Open "DISCUSSIONS", then "POWER TRAC", then "LAST POST". All the Power Trac posts will be displayed in order with the most recent at the top.
Next, click "Favorites", then "Add To Favorites". Whenever you open that Favorite, all unread Posts will be highlighted! Upon opening a highlighted Post, the new threads will be marked "NEW"!

menchhofer · May 21, 2005

I just replaced the thermal switch on my 1430 and the inline fuse and the fan still does not come on. The circuit has power as I jumped over the thermal switch straight to the fan.

I believe I will need to wire it direct to come on with the ignition switch as others here have done.

J_J · May 22, 2005

With every thing hooked up correctly , turn the ign switch on, and put a heat gun, or hair dryer on the switch and see if it comes on. If it doesn't activate, I would holler at PT. There should be a temp setting on the switch somewhere. Is it a Pt thermal switch? Bypass it if you have to.

pequeajim · May 22, 2005

If you jumpered over the temp switch, wouldn't that do the same thing? /forums/images/graemlins/ooo.gif

menchhofer · May 22, 2005

Excellent idea with the hair dryer.

I tried it and the fan came on. I have been using the PT for about an hour earlier and the fan never did come on. I wonder what the temp setting is on the switch/how hot the hydraulic fluid must get before the fan will turn on?

J_J · May 22, 2005

Look at the switch carefully top and bottom. Should be a temp reading on it, or the box it came in, or ask Terry. It probably comes on in the range of 150 deg. you could wire a switch across the terminals if you wanted the fan to come on when the ign switch is on. With the switch off, circuit works normally.