Series 60 DDEC II Mystery

RichardEntrekin · January 02, 2010, 07:59:41 AM

I was thinking just like that. When I removed the signal and nothing changed on the fan, it seems like the faill safe mode is HIGH fan speed. That would make a lot of sense.

I am going to remove the solenoid powered by the 12v signal and apply 12V to it on the bench to see if it is working. I now suspect this is the problem.

buswarrior · January 02, 2010, 08:02:29 AM

And check to see what the source of the 12 volt signal/feed for the system is?

Perhaps some solid state thingy in between here and there having a fit?

happy coaching!
buswarrior

DaveG · January 02, 2010, 10:23:28 AM

BW, I like your thinking, sounds reasonable anyway. And if it doesn't work that way IT SHOULD!

Don Fairchild · January 02, 2010, 10:35:07 AM

If your Newell is any thing like my Gillig then you have a (4) four wire sender in the lower thermostat housing on the right side of the engine looking from the back forward, it controls the fan. Mine is a 185/215 Deg. sender. On the side of the control box priority valve where the wire comes out it has a bolt head and you can adjust the on off temp some what. I have mine turned all the way in. Mine has a single speed fan on it how ever it will turn at all times, just not at speed when it does not need cooling.

Hope that wasn't to foggy

Don

belfert · January 02, 2010, 10:59:37 AM

I think my fan clutch is single speed. The wierd thing is the fan clutch locks up as soon as the ignition is turned on without the engine even running. I am pretty sure something is wrong, but no idea what might be wrong.

I pored over my wiring diagrams for a while the other day and could not even find a circuit to the fan clutch. There are 48 pages of diagrams and I was mostly looking at the DDEC page although I looked at some other pages too.

DaveG · January 02, 2010, 11:05:16 AM

Belfert, it could be the design. It is as posted above, a "fail safe" thing. There are usually two different ways to wire something, one is NO for normally open (either an electric circuit or air on/off) and NC for normally closed (same deal, only the circuit either air or electric is off or closed). This is so that if a wire or air plumbing or whatever fails during operation, the fan goes into a fail safe mode, which in this case is that it stays on.

Don Fairchild · January 02, 2010, 11:44:56 AM

Brian;

you probably have a Horton eddy current two speed fan clutch. You can go on line to Horton and find the wiring diagram.

Don

RichardEntrekin · January 04, 2010, 07:24:31 AM

Ok, here is an update, and what I have learned.

One, it is typical design of two speed or proportional hydraulic fan controllers to fail in the wide open mode. I learned that from the Eaton and Bosch sites. Also, there is a manual adjustment on the controller to control the max fan speed.

Two, the design specs on the Series 60 Tstats are: start to open at 183 and wide open at 207. As others have stated 190 is the target operating temp.

Three, the coil that actuates the proportioning valve on the hydraulic fan controller was OPEN when I ohm'd it. So it was bad.

Newell is sending a new coil for 30.00, cool that I didn't have to buy a new valve. I probably could have sourced it locally, but the numbers on it were long faded away.

I'll update on the temps when I get the new coil installed and it warms up enough to go out for a spin.

Thanks for all your help in getting me started on figuring this one out.

buswarrior · January 04, 2010, 07:33:54 AM

Thanks for reporting back!

Excellent sleuthing!

happy coaching!
buswarrior

RichardEntrekin · January 10, 2010, 06:28:31 PM

Here is the update. As discussed earlier the failsafe mode for the hydraulic fan is to run at max speed. The coil on the solenoid that controls the flow to the fan motor was bad. When a new coil was installed the fan started to function as normal, in that it was no longer running when the engine was below temp.

It had been running all the time before the discovery of the faulty coil. Newell had a new coil in my hands the next day after calling. I do like it that they do not gouge you on spare parts :-) I also found the part locally after the new one with legible part numbers got here. I didn't mind paying 4 extra dollars to Newell to get the right part the first time.

I went for a short drive to confirm temps, but dang it was in the 20's here in Fort Worth this morning, and I'm not sure that is a good test of where the engine temps will settle out now.

Thanks again for your help.