I have an issue with the clutch fan kicking in. I was under the impression that once the temps started to get around 195-200 degrees the clutch fan would kick in. With mine, it starts to kick in at just slightly over 180 degrees and once it gets slightly under 180 it will kick out. The radiator was rebuilt about 4-5 years ago and the fan clutch is new. ( The old one worked the same way ) Before the radiator was recored the fan clutch would kick in at around 195 degrees. It seems this all happens when the outside temps get above 80 degrees. I have 180 degree stat in it now and I'm thinking about going down to a 170 degree stat but don't know if it will do any good. The front of the MH is sealed up so any air coming through the grill goes through the radiator and the air dam is in place. Today coming home it was about 70 degrees outside and the engine ran right at 180 and the fan never kicked in.

It sounds to me, as if it's working? The coolant temp is staying at 180-degrees, so what difference does it make if the fan cuts in or out? Your thermostat is set for 180, so it's probably open....and I doubt that all of these components are extremely accurate with regard to temp., so a degree here or there shouldn't make much difference.Is there a specific reason that you are upset that the fan clutch is engaging? Loss of mileage? Noise? I don't see how changing the T-stat would help with that?Happy Camping:)

Yah, it's a noise problem. You can't talk on a phone or you really have to raise your voice to talk. I know I could insulate the dog house more but I don't think it will knock down the "roar" that much. The other thing is once it is over 80 degrees it's mostly on and that get tiring.

Do you have the dash A/C on? This will cause the temps to elevate and the fan to engage also!

If you replaced the fan clutch with the exact same one, it will probably act the same. You need to find a parts house that can look up a fan clutch that will cut in at 195 degrees. If your coach holds fine at 180 degrees, and you normally do not need the fan to cool things down, then you need to change fan clutches. A good parts house or a GM dealer may be able to help you. Perhaps you need a severe duty clutch from one of the large GM trucks.

The fan clutch engagement is not influenced by internal engine temperature. The internal temperature is a direct result of what the radiator and fan clutch are doing in unison. As a radiator gets restricted/older the center of the core is where this restriction normally occurs. With the center of the core restricted the fan clutch does not have heat to read off because a restriction is a cold spot in the radiator. Since the temp radiating off of the center of the core is colder than the portion of the core actually dissipating heat the fan clutch kicks in later, if at all, and the engine runs warmer due to less cooling area and a non-reacting clutch. Now that your radiator is dissipating across its entire surface your fan clutch is reacting correctly. Randy

Clutch fan operation | Good Sam Community

18 Replies

randallb
Explorer
Aug 10, 2013
Brian,
When setting up a cooling system there are a few basic rules. First, obviously, is a good radiator. Second is a thermostat that opens before the fan kicks on. When setting up cooling systems for my HP/Hot Rod customers I would always specify a fan switch, most guys ran electric fan(s), a minimum of 10 degrees hotter than the thermostat. You always want the thermostat open prior to an electric fan engaging. If the fan were to come on at 180 but the thermostat was a 190/195 the thermo would be late to open because the heat would be drawn out of the upper rad hose by the fan keeping the radiator to cold. In the case of a fan clutch you can have a fan clutch that engages below the thermostat because the radiator which it reads off of will remain cooler than its engagement point until the therm opens. This is the reason a fan clutch is actually better to use than electric fans when designing your cooling system. Electric fans are a compromise made because of space limitations. Having a fan clutch that comes on slightly before the thermostat opens, say 180 to a 185/195 therm, is good because it will still free wheel while the thermostat is closed but will engage almost immediately when the therm opens and the radiator starts to dissipate heat. I am trying to figure out why you are chasing this ghost but if you want to increase the temp your engine is running at, like your original post indicates, install a hotter thermostat and your problem is solved.
Randy
BrianinMichigan
Explorer
Aug 10, 2013
I guess I lost track of the thread. I have not been anywhere with the MH since I started this back on the 21st. I decided not to do the 170* stat for now. spcorvette I wish that was the case with mine. I am going to try something a friend suggested. I will let you all know what happens or doesn't happen after I get back from the UP.
spcorvette
Explorer
Aug 09, 2013
I have used the aftermarket clutches. They seem to come on too early and often. I went back to the GM fan clutch. It usually comes on around 220 and shuts off around 190.
Terry
Gjac
Explorer III
Aug 09, 2013
Brian how did you make out with your fan clutch?
Ozlander
Explorer
Jul 22, 2013
Brian in Michigan wrote:
I hate to go looking for another, I just spent $250 on this one from GM

They saw you coming. You can buy them all day long for 60 - 70 bucks.
BrianinMichigan
Explorer
Jul 22, 2013
I hate to go looking for another, I just spent $250 on this one from GM
1fastdad
Explorer
Jul 22, 2013
Sounds to me like the clutch fan is doing its job.
wolfe10
Explorer
Jul 22, 2013
Brian,

If the middle part of the radiator core was plugged, the air reaching the fan clutch would not have picked up enough heat to trigger the fan clutch to HIGH. So that does make sense.

See if yours has a second detent hole. If not see what other clutches are available. The fan on high is not only noisy, it takes HP and MPG.
BrianinMichigan
Explorer
Jul 22, 2013
Gjac wrote:
Brian I have heard that some clutch fans have two notches to set the Bi-metallic coil spring in front. Loosening it makes it come on later. Mine is a 1996 vintage and does not have this adjustment. If you wanted it to come on at a higher temperature and it only had one slot I would try to insulate it with something like silicone spray. I cleaned mine with some solvent and a tooth brush because I wanted it to come on sooner.

I was wondering if I could manipulate the spring somehow to delay the kick in of the fan. I just find it odd the with the half plugged core the fan kicked in at 195 now it's just over 180. I am looking at a 170* thermostat from Summit and trying that to see what happens.
Gjac
Explorer III
Jul 22, 2013
Brian I have heard that some clutch fans have two notches to set the Bi-metallic coil spring in front. Loosening it makes it come on later. Mine is a 1996 vintage and does not have this adjustment. If you wanted it to come on at a higher temperature and it only had one slot I would try to insulate it with something like silicone spray. I cleaned mine with some solvent and a tooth brush because I wanted it to come on sooner.