My 425 fan failed!!

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

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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.