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Topic: Forcing Cooling Fan High Speed (Read 856 times) previous topic - next topic

Forcing Cooling Fan High Speed

I've got the common setup with two fans controlled by hydraulic fluid passing through a Thermostatic valve in the coolant flow. I read several posts regarding this valve. Anyhow, mine works fine but I'd like to be prepared in case of an overheat situation now that we are completely reliant on the rig. Do I understand correctly that the only way to force high speed would be to remove and plug the individual hoses and the valve? Thanks.
jor
93 225
95 300
97 270
99 320

Re: Forcing Cooling Fan High Speed

Reply #1 –
Here is a previous post on the subject:

Manual fan speed control for our 99 U270

Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: Forcing Cooling Fan High Speed

Reply #2 –
Thanks, Keith. I read that one. I'm not looking for anything as elaborate as Dave's solution (no retarder here so no inherent overheat issue). My motors have no electrical wires that I can see so no solenoid. I think it's just the wax switch/valve. I guess I could do as Barry did and install a ball valve to interrupt the flow. Now that I think about it, I suppose that would be the way to go. Just wondered if anyone else has considered this as a strictly just in case deal like the air dryer bypass (now carrying a union!).
jor
93 225
95 300
97 270
99 320

Re: Forcing Cooling Fan High Speed

Reply #3 –
Jon, you may not have a two speed switch. Mine does not. Mine is variable and correlates to the rpm of the engine. The two speed switch wiring on mine was not connected to the speed control valve. Some of the 93/94 Unihomes had this setup. If yours is wired then as I recall you can simply pull the spade connector and the control valve will automatically go to high speed.

Hope this helps.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Forcing Cooling Fan High Speed

Reply #4 –
Quote
If yours is wired then as I recall you can simply pull the spade connector and the control valve will automatically go to high speed.
That's the thing. No wires on mine. Just the two hydraulic hoses.
jor
93 225
95 300
97 270
99 320

Re: Forcing Cooling Fan High Speed

Reply #6 –
My 95 U240 with CAT 3116 has 2 hydraulic fans, it has a high/low hydraulic value located on the drivers side.  The solenoid is controlled by a temp. sending unit just below the one for the dash temp gauge.  To force my fans to high speed, just remove the ground wire connected to the frame.  I used spare wires going to the dash area and a rocker switch to connect the ground to the solenoid and remove it for high speed. Works good.
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Forcing Cooling Fan High Speed

Reply #7 –
Yes, some are electrically controlled, some wax capsule controlled.

Totally different systems with totally different controls.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Forcing Cooling Fan High Speed

Reply #8 –
Quote from: wolfe10 –
Yes, some are electrically controlled, some wax capsule controlled.
And some have NO control.  To the best of my knowledge (which is limited) our coach has no type of active cooling fan control.  I have traced the hydraulic lines from the pump to both fans and back.  Can't see any kind of limiting/controlling valve.  It appears the fans simply speed up as the engine rpm increases, until they reach the limit imposed by the (internal) hydraulic pump pressure regulator.  Does this sound correct?
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Forcing Cooling Fan High Speed

Reply #9 –
Quote
If you coach has the same thermostatic hydraulic valve, what we did may help you:
Yep, that is just what I have. Thanks, Barry. I think I'll pick up a ball valve. Thanks to all.
jor
93 225
95 300
97 270
99 320

Re: Forcing Cooling Fan High Speed

Reply #10 –
We had an overheating problem going to Illinois last year.  Thinking we were stranded I called James T who told me to unplug the module forcing the fans to high speed.

I had to unhitch the Jeep to get the bay door up (and it was snow and sleet by then) but was I ever thankful when I heard those big fans crank up.
Rick & Rhonda
2003 U320 4220  Build #6199
Was
91 36' GV 300 Caterpillar, 92 40' U280 300 Cummins, 97 36' U295 300 Cummins, 2002
U320 450 Cummins
(Guess we're hooked)

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Re: Forcing Cooling Fan High Speed

Reply #11 –
Attached somewhere on the body of the engine compartment (mine is on drivers side, close to the air filter housing) is a solenoid that activates high speed. If you take the top bolt off, the upper assembly of the solenoid will lift off. With the top off the fans default to high speed.
1994 U280, Build 4490
Deming, NM.