Manual Engine Cooling Fan Switch

[obedb]

We recently purchased a 2003 Phaeton 40' with a 330 Cat powered Freightliner chassis. Other than shuttling it around for service and new tires, it hasn't been used. My guess is that the engine fan has an air operated fan clutch. I don't see how a viscous clutch would work with a rear facing radiator. I would like to install a toggle switch on the left side of the driver's seat to turn the fan on when starting a hard pull especially on a hot day. I had manual fan switches on all of the tractor trailers that I have driven for over the last twenty years of my trucking career, and I know there value on a hot day. With a rear facing radiator they seem even more necessary. I have seen a number of DPs on the shoulder of a long grade probably cooling down (my guess).

Eliminating power to an electric over air fan clutch usually causes a constant run. Would a fused switch that eliminates the fuse dedicated to the fan work?

[desertdeals69]

Does it have a fan clutch? On mine and several others that I have looked at the fan is direct bolted to the shaft with no clutch at all.

[dickandlois]

ObedB, As mentioned by DD69. Many of the cooling fans are bolted directly to the engine, for the ones with the radiator in the rear. On the side mounted radiator units, the fans use hydraulic pressure to power the cooling fans.

I can not recall seeing any air operated cooling fans on the RV's

The fan speed on the side mounted units is controlled by temperature sensors in the vicinity of the CAC and the radiator and dash AC condenser.

There is a fan circuit on some models controlled by the ECM.

I need to check and see if I have any information covering the cooling system on your model and year on file.

You may want to call the coach builder and ask them if a manual switch can or could be added.

Rich.

[obedb]

On the Tiffin RV independent site, I read just yesterday about programmable cooling fans on the 43 footers (the Bus I guess) and some really high temps on the cooling systems of respondents while climbing hills. Bolting a fan directly to the shaft is really old school. That stopped in the 70's on commercial truck-tractors. The first effort was the viscous clutch, then the air operated clutch that only worked with 12volts applied, and finally the fail safe air operated fan clutch that was always on if there was a broken wire or blown fuse. I am not new to motor homing . We owned a 34' gasser for 17 years. New to DPs, but certainly,not new to large vehicles powered by diesel engines. I started driving them in 1965.

If you folks are right, what a fuel waster. Commercial trucking went to fan clutches to save fuel. Cooling fans draw a lot of horsepower. Kenworth even programmed their fans to come on when the engine brake activated. I had that stopped on mine. It was annoying. On a long downgrade, if I felt that I needed some more braking I turned the fan on with the switch near my left knee.

Dumbfounded I am.

[wolfe10]

Yes, the vast majority of rear radiator coaches have direct/bolted fans (yes, there are a few-- have seen one on a Freightliner chassis with MB engine).

Side radiators are a very different matter, as they are rarely mechanically driven (yes there are some). Most are hydraulic driven so can be relatively easily thermostatically controlled.

[duanelin]

My 2012 Diplomat 43DFT with a maxxforce 10 engine has a air clutch. Just had it replaced at 16000 miles. The solenoid that activates it failed causing the clutch to fail.

I am pursuing a warranty claim with Monaco/ARG at this time.

Duane

[obedb]

Oh well! If I do have a fan bolted directly to the shaft, I will be wasting fuel, but I won't have to worry about a switch. When I start up a grade on a hot day, I will keep my rpm up to move more water through the radiator and hope for the best. Rather than being on hold for a long time, I have an easy way to tell if the fan is bolted that saves trying to crawl underneath on a gravel covered storage yard. Just assumed it would have a clutch in order to save fuel.

Re: 16,000 miles and a failure. Fan clutches last hundreds of thousand of miles on an 18 wheeler. Kinda thought some of that durability would be built into a DP.

[kaypsmith]

ObedB,

Us bus nuts often add radiator sprayers to our units for cooling on steep grades, pretty easy install and works!!!!

[obedb]

Is there a post on this site for a sprayer? Are they custom made or available at retail? I am heading across Kansas in late August. Last year in early September it was 100 F. Contrary to popular belief, Kansas is not completely flat on I-70 and then there are often headwinds. Managed with my F-150 pulling a travel trailer and grossing 13,800, but I had a front facing radiator and a good set of gauges.

When I get to Poncha Springs, Colorado I have Monarch Pass to deal with. Probably won't be a scorcher up there, but it is a long hard pull.

[desertdeals69]

If you use a sprayer you should use pure water or you will corrode the radiator in a short amount of time.

[wolfe10]

Have you checked the front of your CAC (Charge Air Cooler) for blockage. It is an often neglected item and that is where dirt and debris collects.

Verify that the perimeter, particularly the lower perimeter is as clean as the center-- the fan blades sling the dirt to the perimeter.

This should be an annual "cleaning", but is often neglected. I have seen CAC's (remember, the radiator is BEHIND the CAC) that are 40% plugged. Hard to keep them from overheating.

[obedb]

Fired her up this afternoon. Grill up. Nice flow of air coming through the radiator from all areas. Had the dash air off so the high pressure switch would not turn on a possible fan clutch. Guess it is just bolted on and belt driven. Short of being a contortionist and working my way up from the gravel it is parked on alongside the engine I don't know how to even get a look at Cat yellow. No access up top. Sure do miss popping the hood for a look. My guess CAC receives first blast of air and then the ac condenser or are they both mounted to get an equal amount of the fan's first blast? Where can I see a chassis of this age before a coach was built on it? 2002 chassis and 2003 coach. If it was stored on concrete or blacktop I might be able to get alongside the engine even at 70yo.

Wasn't used hard. All 17,644 miles over 11years were put on primarily running back and forth to Myrtle Beach from Taneytown, MD before we bought it. Plan on a VMSpc system to watch EGT, Boost, and tranny temp.

[wolfe10]

I would be quite surprised if you do not have some access to the top of the engine from the bedroom or closet. That is where you would be able to see the fan shroud and front of the CAC.

And, with a 2002 chassis with Caterpillar engine, it is quite likely you have a grease zirk for the fan hub-- it would be accessed from the bedroom or closet as well.

To verify that you do have one, call the Caterpillar RV Hotline with your engine serial number: 877 777-3126. If difficult to access, it may have never been greased!

You also have a separate V belt that drives only the engine water pump. It is NOT on an automatic tensioner. Make sure it is not loose. Check tension from the driver's side of the engine from below (water pump on driver's side of engine).

[obedb]

The water pumps on the big guys (C-15) are gear driven. Guess I can't be that lucky. I have looked for access from the bedroom. Can't find it. A long call on hold is next for me with Tiffin. I will call Cat with the engine serial number to check. Big guys don't have that issue either. Thank you for the help. Will do everything that I can to follow up.