Community Forums

EngineerMike · 09-05-2010, 07:31 PM

The original part numbers (Saur-Sundstrand era) were:
B5531-09856-ETC 194°F
B5531-09857-ETC 199°F
B5531-09858-ETC 205°F
B5531-09859-ETC 212°F
The temp chosen was (is) to match the begin-control-fan speed setting desired. The range of the valve is 12° from min to max fan speed. The valve setting may not match engine temp exactly since the valve placement isn't on the engine but usually in the coolant stream. I believe the WRV placement is on the coolant input to the radiator to get as close to in-engine coolant temp as possible. Not sure what exact degree setting that would be for best operation. The "ETC" gets filled in w/the pressure level in units of BAR, from 30-210 BAR (435 to 3000 psi) in increments of 5 BAR (72.5psi). Hax's part# in post#6 would seem to indicate 190 BAR or 2755 psi.

Just my $.02- the 9857 valve opening at 199° seems about right to me. Full fan @ 213 in the coolant pipe to radiator sounds like the ball park.

Old Scout · 09-08-2010, 09:56 AM

This thread continues to be a topic of discussion. I have made several attemps to "fix"/improve the performance of the dash air conditioning on my 2003 and have met with only limited success. The worst outcome was asking an RV repair shop to diagnosis and repair the system--they replaced the wax valve and were pushing me to replace the fan motor before I terminated the relationship.

My experience is limited to working with the mechanical wax valve assembly on 2003 and earlier coaches. Sometime in 2004, WRV went to an electrical control that has its own set of issues. The attached [I hope] picture shows both the OEM wax valve on the left and the after-market solenoid solution I installed on the right.

There are a number of root-causes for poor dash a/c performance, eg, freon level, compressor, evap/dryer tank, freon oil content, fan timing/speed. Any/all could be contibuting to the problem--most Rv shops dont know/ wont learn how this system works before suggesting "solutions".

Bottomline: My engine cooling system works perfectly--my dash a/c does not!!!!!

F&D ABQ · 09-08-2010, 10:44 AM

Old Scout,
You didn't explain how the new arrangement works. I understand that the thermovalve is open below 190 and gradually closes above that, so would your solenoid valve simply shut when it receives power from the two red wires, thus maximizing fan motor speed? And do the two red wires go to a toggle switch or to the same switch that turns on the A/C?
Also, did you look into replacing the wax valve with an electronically-controlled substitute?

Old Scout · 09-08-2010, 04:28 PM

Good questions Frank--this is basically a summary of the post I made to the earlier thread on dash a/c and engine cooling problems. In a nutshell, the after-market solenoid is tied (via relay) to a spare freon pressure sensor on the front firewall [this OEM sensor was designed by ACME to start/stop aux. electric cooling fans on the main radiator--not used by WRV]. Even when the wax valve is working as designed, the a/c radiator will not always get air flow until the diesel engine achieves operating temps. Consequently, the dash a/c system can get very hot with very high freon pressure before the engine hits ops temp and the wax valve kicks the fan on. The spare sensor settings are a bit low but it does ensure the solenoid overrides the wax valve and starts the fan before the a/c freon is over-pressurized.

Given the simplicity of the wax valve, you would think its performance would be predictable--mine was not! "Sometimes" my engine fan comes on at start-up [be it at a slow speed] but if you turn the engine off before reaching ops temp, the fan will usually stall until the wax valve reaches ops temp and kicks the fan on. IMHO--repeated high freon temps and pressure cannot be good for the a/c system [compressor, hoses, radiato, etc].

This was the retrofit solution WRV was doing until they switched to the electric controller. As for retrofitting an electric controller on a wax valve model, I wouldnt even know were to start with integrating the new controller into the EMS--suspect the cost might be prohibitive as well--and again, it wasnt what WRV was advocating at the time. The good news is that my engine cooling system [with wax valve] has always worked well.

EngineerMike · 09-10-2010, 07:38 PM

Scout- can you post the part#'s for the solenoid/valve?

Here is the Sauer diagram of Scout's addition:

EngineerMike · 09-10-2010, 07:49 PM

According to Sauer's literature, the fan should "idle" at about 15% of full speed with the wax valve, but in doing so will only use 3% of the rated horsepower of the fan motor. full speed is about 3000rpm, so 15% is 450rpm. Looks from the above diagram that the wax valve (or electronic control) allow a bypass of the hydraulic fluid when cold; when the wax heats up it constricts flow in the bypass, pushing more thru the fan motor.

The electronic control gizmo used on later engines uses a pulse width modulated signal between 10 & 90% to control a stepper-motor-operated valve, doing the same thing as the expanding wax closing a needle valve. Current versions of the electronic control have up to 3 independent call signals that can put the fan on a preset over-ride level (like "full speed" for an air conditioner ON signal, or trans temp override of engine input). The trick is programming something to send the pulse-width-modulated signal (the AC call is easy), if you are contemplating replacing the wax w/electronics. there are probably temperature transducers that can be used, but adapting would be some work.

Old Scout · 09-11-2010, 08:27 AM

EM--let me see if I can find the packing slip on the by-pass solenoid. I was chasing this solution thru Grainger before making contact with Mark H [sorce for Mark wsa Spencer Fluid Power]. Suspect there are any number of sources for the solenoid. Even though WRV was using this solution as a retrofit, Mike Young? [Yakima Cummins] was concerned about sudden torque on the air compressor/hydraulic pump drive shaft if the inputs were not modulated. Ref my earlier post, I am still not satisfied with my dash a/c performance but since the engine cooling works fine, I really dont want to "tinker" more with this than I already have.

PS--great explanation of how the fan runs at cold startup. I have never been able to understand the variations at startup [ie wax valve open] --sometimes the fan runs at slow speed and sometimes it doesnt run at all until engine ops temp is reached.

EngineerMike · 09-11-2010, 04:03 PM

Sauer's docs say the wax valve goes from min to max over "12-15°F. This eliminates sudden changes in speed that would cause dramatic changes in noise levels and place high transient stress on drive components. Without modulation, as the fan 'cut in' occurs withe engine at maximum speed, the fan would accelerate almost instantly from rest to perhaps 3000 RPM. Such high acceleration requires proportionally high driving torque and makes the achievement of reliable long term operation more difficult." so the mfgr shows a 3° variation. My guess regarding some vs. no RPMs on cold start is that the variation implies the end points are not hard stops, or else the wax varies over time as it wears from repeated expansion/cooling.

I'll be posting the fan motor technical info to the Tech Library shortly. I also received recently a Chassis Data Card from an 01 model 34 feeter. It shows a fan motor from Sauer-Sundstrand part# B5511-1143-170 and a fan motor thermovalve part# B5531-09857-190 (which matches the above post w/wax valve part#). That's the 199° cut-in unit previously discussed. While I'm naming names, the Sauer-Sundstrand hydraulic pump (shaft-driven off the forward end of the engine's air compressor) is part# B5501-35765-160-160. Since it appears the wax valve model has changed little over the years, the fan motor & pump numbers should also be recognizable to hydraulics vendors worth dealing with if need arises.

McCown · 09-20-2010, 04:50 PM

Mike, can you bypass valve and have it run on high all the time.
Bandit2002

F&D ABQ · 09-20-2010, 05:13 PM

Quote:

Originally Posted by McCown

Mike, can you bypass valve and have it run on high all the time.
Bandit2002

Bandit,

Look at Mike's post above - the valve is in bypass mode when cold. When hot, it closes. That's what the solenoid valve that Old Scout installed does - it's in series with the wax valve. I guess you could just put a manual valve in the line to accomplish the same thing, but it would of course cause extra wear and tear on the hydraulics, load the engine, and reduce fuel mileage.

Old Scout · 09-20-2010, 09:24 PM

Besides excess wear and tear on the fan motor and hydraulic pump, having the fan run continuously at full speed will cause the engine to run well below normal ops temperature. Aforementioned RV shop tried running the engine with the control loop physically blocked; engine temps stayed in the 170s during prolonged fast idle--so probably not a good idea.

EngineerMike · 09-21-2010, 03:13 PM

Actually prolonged idle, even fast, should be 175-ish. However, I wouldn't recommend full fan eternally regardless.

palehorse89 · 11-25-2010, 11:13 AM

My fan was also roaring! I found the adjusting port on the valve body and turned it in a bit,the fan slowed way down and the roaring stopped. I have not driven it yet to watch the coolant temp. After warm up. That will be next. Al least it is not sucking my shirt off me on a idle.

Refuse1 · 04-04-2011, 01:07 PM

Since it is documented that it takes just about forever to get one of these fan control valves, I went ahead and ordered one to have on hand and it just came in. (about 3 months)

The Sauer Sunstrand part number is 533109857190

If somebody who has actually seen one of these rare creatures in person before could verify that this looks like the correct part, I'd sure appreciate it.

Thanks,