Electric fans in front of radiator

[cncsparky]

There are a couple of electric fans in front of the radiator and condensor.  They appear to run off of a temperature switch in the upper radiator hose, if you look in this pic the upper hose is visible with a spliced section and a sensor attached.  Is this typical?  Do the fans turn on at the same time?  I figured at least one was for when the AC was on, but wiring looks like they both run based on coolant temperature. 

I pulled the condensor out due to damage, will these fans still do any good with the gap now between them and the radiator?

[tntwardell]

That is typical.  The electric fans are added for better cooling during times with high rpms but low speeds like climbing hills. The clutch fan on the engine dont work well at high rpms becuse most vehicle's are crusing down the highway and the wind does the cooling. Both fans should come on at the same time and will be just fine or better without condensor

[MotorPro]

the fans will still help but ideally you should either move the fans closer to to rad or extend the shrounds up to the the radiator

[cncsparky]

Thanks.  If I move the fans, wondering if it would be better to upgrade to more modern aftermarket units?

[DaveVA78Chieftain]

The fans should be mounted up against the condensor or radiator as applicable.  You removed the condensor so now the air can escape around the outside of the fan when you are sitting at a red light or stopped for any reason.  The condensor funneled the air to the radiator when it was there.  Maximizing air flow by ensuring it is directed through the radiator is the purpose of fan shrouds and why aftermarket fans are mounted directly to the radiator.   At speed, the fans are not needed as air is forced trough by the movement of the vehicle.  They are needed at slow speeds and when stopped.

I think those should work ok.  Newer design fans would be more for noise reduction.

Dave

[cncsparky]

OK, I looked at the bracket and it seems I can move the fans forward some.  Just not sure if it will be enough to get them close like it was to the condensor. 

[Thundercloud]

If you want to really cool it you can add a racing coolant additive that may lower the boiling temp of the radiator fluid. Ask for it at your local auto parts store. I think it even cools it about 10 or 15 degrees. I remember it to be purple stuff.

Good thinking though. It must be aftermarket. My 79 Winnebago doesn't have electric cooling. Just a flex fan. I heard by removing the flex fan and adding electric you can gain a few horsepower. I might look into those myself. I recommend a mechanical temp gauge. They are more reliable in my unproffesional opinion.

[cncsparky]

Water Wetter is available at most parts stores.  Its supposed to enhance the coolant by allowing the water molecules to fit more closely to the metal engine components.  I 've used it before and will probably add it to my RV.

[Lefty]

There are two types of factory fans. The first type is a thermostatically controlled fan clutch, and the second type is a centrifugal clutch. The thermostatic clutch can be identified by a small bi-metal coil located in it's center. This type engages when the air passing over it increases, and disengages at lower temperatures when cooling is not needed.
The centrifugal clutch does not have a coil in the center, and engages at low rpms but releases as rpms increase.
Both styles have built in over rides that allow the fan to freewheel when the force of incoming airflow is greater than the force needed to turn the fan blades. This allows both types to free wheel at normal cruising speeds, at normal temperatures. The thermostatic type will still engage if the temp increases enough to lock the fan even at highway speeds.. but the centrifugal type will not lock unless engine speeds decrease enough, and the airflow drops enough for the clutch to overpower the airflow.

Both types are very efficient, and work quite well... with the thermostatic type having an advantage in high heat conditions due to it's design of locking as heat increases.
Both types use a silicone based viscus fluid as it's operating medium, and this fluid does have a normal service life of about 5 years. As the fan clutch ages, it loses locked operating rpms, and after 5yrs is virtually ineffective. Thus both types must be replaced at a regular interval as normal maintenance. The factory centrifugal style works very much like an aftermarket flex fan at high engine rpms.

With a properly operating thermostatic clutch fan, you should hear a distinct fan noise engaging and disengaging at regular intervals wit the engine idling at normal temperatures. This type will freewheel with the engine off, but cold. It should not freewheel more than 1/2 turn by spinning by hand if the engine is off, but warm.
The centrifugal type can be tested by running the engine to a steady 2,000rpm. The fan should disengage and freewheel as the engine rpms increase above that point, and re-engage as the engine rpms drop below that point. A centrifugal style should not free wheel more than 1/2 turn when spun by hand with the engine off, regardless of engine temperature.

[MotorPro]

Don't waste your money on Water Wetter. I have tested it it several vehicles. In race cars we found a slight gain,unfortunatly the race Water Wetter can not be mixed with antifreeze. Not much use in a motor home. The street stuff we tested in several street rods and never found it to help at all.

[Oz]

Which leaves the obvious question: "Isn't water alread wet?"  Kinda like needing a "hot water heater"...
N:(

[Stripe]

I've used water wetter in my Porsche 944 to great effect. (not that a 944 really needs it.)
But I was living in San Diego and did not mix coolant into my water.


I miss my 944 and PCA SD events..   

[Rickf1985]

Lefty, I would have to take issue with the five year rule on the fans. As a master mechanic with 40 years of wrenching under my belt I can tell you that I have not had to replace all that many fan clutches due to wearing out in that short of a time. I quite regularly saw engines with the original fans with well over 100,000 miles and ten, fifteen, twenty years old. I have four myself right now including the MH. I did replace the one on the MH because I was doing the water pump and it was so damn hard to get to but it was still good and I have shelved it just in case. I have a 96 F-350 diesel and a 84 Chevy K-30 diesel that both still have their original fans. The Ford has 365,000 miles on it. My 98 Dodge dually has 168,000 and has it's original fan clutch.

Rick

[Lefty]

 "I did replace the one on the MH because I was doing the water pump and it was so damn hard to get to but it was still good and I have shelved it just in case. "

Actually, it's recommended that you replace the fan clutch anytime you replace a water pump. They both share a common shaft, and the failure of one parts bearings can cause vibrations that will quickly result in the failure of the other.

Whenever a customer complained of repeated failure of either a water pump or a fan clutch, over a short period of time, we always would look to see if the other part had been replaced as well. If it had not, 99% of the time replacing the other part would cure the repeated failure issue.

But hey, at least you've got an emergency spare.

[ramit]

our itasca has a clutch fan but also a flex fan idont feel the flex fan belongs ..been looking for a ridged fan to replace the flex ...i feel the flex defeats the propose of the clutch ....and the PO was saying the pressure valve on the cab A.C kept poping off i frigred cause of overheating ...any opinons on this ?  W%

[Rickf1985]

The A/C was most likely overcharged or not vacuumed down before charging and has moisture in it. It should be reclaimed, new receiver/drier installed and then vacuumed for at least an hour and then recharged with the correct amount of refrigerant.