Community Forums

Marca · 03-02-2011, 10:40 PM

We are currently at Cummins Coach Care in Ocala, FL trying to determine if we have an electronic hydraulic fan controller problem. Our coach has been running somewhat cool (both engine and transmission) and they have determined the fan is running too much causing the excessive cooling of both the engine and transmission. Of course, the weather here being unusually cold this winter has not helped with the diagnosis of whether there is a problem or not.

I have located the information on IRV2 regarding the part and how we need the numbers off of it to get a new one; however, Cummins here is not real eager to tackle it and says it is really an OEM problem and out of their realm. They have agreed to do a little more checking tomorrow concerning the temperature sensor on the intake manifold to rule a faulty sensor out.

Has anyone had to have this part replaced and if so was there a lot of difficulty getting the part? Does anyone know of a shop in the Ocala, Orlando, or Tampa areas that we could contact for assistance? Is a Freightliner shop what we should be looking for?
Thanks!

Marca · 03-04-2011, 02:02 PM

Cummins did some more checking and determined that the temperature sensors were functioning properly; however, when they wiggled the electronic hydraulic fan module it went to high fan which is the fail safe mode. They said it looked like it was not supported properly and was most likely moving about and affected the wiring. No idea how long it was that way. Thanks to information on this forum, I was able to help them get to the correct company (Saur-Danfoss). Actually, the supplier was Hydro Power right in Ocala. Cummins was able to read the part numbers off the old part and ordered it through Hydro Power. It will be shipped from Saur-Danfoss in Ames, IA on 3/9/11 and we will return to have it installed and securely fastened. Strangely enough, Chuck's Army Buddy recently retired from Saur-Danfoss in Ames after working for them for years. Small world, huh?

A big thank you goes to Jim Munsil, ACA and ACE member, from Ocala who read my earlier post and traveled over to Cummins to see if he could be of any assistance. We really appreciated him taking the time to see if there was anything we needed. We had a nice chat and he helped verify that my internet searching for the part was on the right track.

Chuck will try to get some pictures of the problem and I'll try to post them as soon as he does. And, we all thought that Engineer Mike had the coolest running coach. Maybe so, but right now ours may be in second place.

Twomed · 03-05-2011, 02:59 PM

RV.Net Open Roads Forum: Class A Motorhomes: Monaco Parts by Sauer Danfoss Here is a thread on the problem controller. There is also a place close to Atlanta that rebuilds/reprograms these. The Atlanta place is in athread on the BAC board. If you email Richard Ames I'm sure he can direct you to the thread. Mine quit and I am working on a project to replace it with relays and an added thermostat....still in testing, but I just can't stomach $5-700 for a part to turn a fan on and off. It does cost about 2mpg if you leave it ON all the time. I ran with a temporary on/off switch for a while until I got the relay box project up and running.

Hope this helps.

Wayne R · 03-05-2011, 05:04 PM

Twomed, Care to share your relay set up. I have not had problems with the fan switch but like you I don't like the cost of the replacement.

bluepill · 03-05-2011, 05:23 PM

Interesting info here:

http://www.google.com/url?sa=t&sourc...qwg7OhoheTm3gA

If this is the system that's used in RV's, it's pretty sophisticated. I wonder if it's s solid state component failure, a software bug, or a circuit board problem. Has anyone examined the circuit board carefully? The OP's description sounds more like a board problem.

Twomed · 03-05-2011, 08:24 PM

Next test run on Tuesday...will certainly post some pics when it gets the way I want it.

Twomed · 03-09-2011, 09:45 AM

Test run was all good. Fan operated as designed for about $50 in parts from NAPA and Radio Shack. Basicaly a DPDT relay, temp sensor, diodes (overkill), a resistor and a project box. About $50 versus hundreds. Mine never worked right from day one, bad answers from Monaco and Sauer so decided to do it myself. As always the fail mode is to be constant fan on so there is zero chance of engine damage. I only got to run about 40 miles in heavy interstate traffic so note taking was limited. The 19th we will be running from Tampa to the Keys so I will monitor the results and post at that time. I used a temp sensor that allows engine to run up to 200 then cools to 185. That is actual fan run time, which on the Aladdin show an almost 2 mpg fuel hit. Hyd fans do take a lot of HP!!

More later with a drawing if interested.

Wayne R · 03-09-2011, 01:33 PM

Thanks for the update. I am interested in more info and drawings.

Stretch · 03-09-2011, 08:11 PM

Chuck & Marcy:

Looking at the problem in a slightly different angle; consider the engine thermostat. That engine thermostat WILL shut off the coolant like a valve. It will prevent the coolant from circulating thru the radiator regardless of the fan setting till the coolant reaches the preprogrammed temp setting of the thermostat. That temp is probably 180 degrees or 190. So I dont see how the fan could make the engine run too cool. On a hot day or steep climb will cause the fan to go on high to cool the engine down. But the fan wont over cool the engine.
Hope someone with correct me if I am incorrect.

Old Scout · 03-10-2011, 06:54 AM

Couple of years ago, I had a simply miserable experience [expensive too] trying to diagnose and "fix" the wax fan control on my 03. Yup--the 03 is a different design from newer coaches with electronic controls but with the control valve by-passed and the fan running full title, all the time, the engine appeared to run in the 170s [vs 190s] after warm-up [perhaps some coolant by-passes the engine thermo, even when closed]. In addition to the temp issue, you also have increased wear/tear on the fan components, reduced fuel mileage, and some concerns from Mike Young at Cummins Yakima about whether any modification to the fan control would cause the fan to engage more abruptly, causing more torque on the hydraulic pump drive shaft {see previous posts for this discussion}....

Wayne R · 03-10-2011, 08:38 AM

Old Scout, I have always wanted a way to shut the fan down for short periods of time while driving on dusty roads and driveways. I always assumed I had the wax valve but maybe mine is electronic. If it is, hooking up an override switch should be relatively easy. Trouble is I never think about it until I am on a dusty surface.

Twomed · 03-10-2011, 09:28 AM

After MUCH Googling and reading on Sauer Danfoss Fan Controllers here is what and how it works.

The small (about 4"x4") component (fan controller)with wires hooked to the coach receives temp inputs and sends voltage to the coli (round 4" tall) component. That coil is an electro magnet that surrounds a stem with a ball inside that is pulled up to allow more hyd fluid to flow and increase fan speed.

The complicated part comes in when you realize that this little controller is designed to be programmed by a computer with an infra red link, and software that covers a multitude of installations. They are used on stand alone industrial diesels for pumps, generators (big)and all sorts of industrial applications worldwide. The RV business is a drop in the bucket for them.

The device is capable of having multiple inputs prrogrammed, and the number was determined by your individual manufacturer based on cost/performance. More input parameters= more cost...you know waht they chose. They all have different parameters based on radiator size, coach weight, engine coolant range, Cummins, CAT, series, size etc. so there are a lot of differences in controller specs.

The default is always...no electric power=full fluid flow...max cooling.so that with any electrical failure the engine gets max cooling.

Ideally your cooling sysem (if clean) should cool sufficiently to keep the engine cool when idling around a campground with the fan off, or at a very slow speed, because the hyd fluid is never really turned completely off. The fan controller limits are set high enough to allow low load operation without high fan speeds. When this device fails you severely dust your spouse when backing into sites....time to fix it!!

Hope this helps.

Twomed · 03-10-2011, 09:57 AM

AND...Scout, Stretch and Wayne to answer your questions. I was afraid to go too long above. Sometimes there are limits to post size,

Engine thermostat opens at 180-182 on most isl 400 apps. The fan controller cooling will always be set to operate in a higher range.

Too cool??? My Dynasty with the fan at full speed/no 12v will actually cool down to about 175 when running 65 mphand the thermostat is just barely open. Depends on weight and radiator size.

Fluid dynamics will keep the fan from banging (0-60) because the valve always has some fluid running through.

I have two coil controller set ups that I experimented with on the bench, a Monaco and a Country Coach. At a full 12+ volts the magnet when enegized snaps in very strongly. At 5.5 volts (resisted down) it will not activate enough to open the valve and turn the fan on. After playing with voltages I settled on 11 to provide an easy fan ramp up and it holds enough fan speed to cool properly...at least in my short run rest above. I will know more about this setup after the trip to the Keys in hotter weather, more distance next week.

Conclusion...overly complicated system...brought to you by the engineers in the northwest that built these magnificent side radiator machines based on their prior experiences in the aviation industry. These guys bounced back and forth between Boing and the rv industry post VietNam and brought their aviation skill sets to the industry. That's why we have numbered/labeled electrical wires, Canon plug wiring harnesses and all the hyd goodies.

As a VietNam era Boeing Chinook helicopter maint officer and test pilot I really appreciate what they bring to the table, that's why we own a northwest versus Elkhart coach. But some days you spend lots of time figuring things out, even with prior experience, when the engineers and even the company are past history. Best thing here is...when it quits you don't drop 6,000 feet down!

Roll on!!

Wayne R · 03-10-2011, 11:22 AM

Twomed,
Thanks for the wright up. My wife and I retired from Boeing after 35 years. I started as an assembly mechanic and retired as an senior manager in charge of 747 production. So I appreciate aircraft style wiring and hydraulic system. My wife retired as a procurement manager.

Although the engineering in our Alpines has a hint of aircraft quality the assembly practices leave a lot to be desired.