Electric fan and fan clutch

[Jimmy9190]

Trying to make a long story short here. This is about my 2001 Dodge Dakota pickup, 3.9 liter V6, manual 5 speed transmission with 145,500 miles on it. A couple weeks ago I noticed my fan clutch was staying engaged for a longer period of time and was kicking in a lot more often. It is very hot here in Florida right now. I checked the fan and found a lot of wobble in the fan clutch itself. I replaced my water pump and radiator hoses back in February, radiator and AC condenser were replaced in March 2010 after I was in an accident. I had already replaced my original fan clutch a month before the accident, I first used an aftermarket TorqFlo from Auto Zone. It made a lot of noise and engaged way too often in warm/hot weather. I got a refund on it, the AZ store manager was great about it. A new OEM fan clutch was out of my budget at the time. I bought a used OE clutch off a 70,000 mile wrecked Dakota. It did OK until now. Since I had learned my lesson on aftermarket fan clutches, I bought a new OEM Mopar fan clutch at the Dodge dealer, list price is $153.00, they sold it to me for $120.00. I installed the OE fan clutch and thought all was well. This past Saturday I went on about a 50 mile round trip in the middle of the day. Our heat index was said to be 107 degrees, it was probably a lot higher than that and the heat coming off the pavement was probably 130 degrees. You could probably have not only cooked an egg on the sidewalk, you could add bacon, toast and grits to it too. I was in a lot of stop and go traffic, and the fan clutch kept engaging all the time. My temp gauge was creeping up and at one point was pointing straight up in the middle of the gauge range and I had less power from the engine. My temp gauge usually always rests right at 1/3 of the gauge range. My AC was not as cool when idling or driving slow in traffic either. Coming home at 60-70 MPH on the higway the temp gauge and AC were both fine. Temp gauge was OK at slower speeds on city and neighborhood streets too. My truck also ran warmer than usual yesterday when I made a 2 mile round trip to McDOnald's. So I thought there was a problem with my new genuine OEM Mopar fan clutch. This was not the problem. My truck has a regular blade fan and fan clutch on the water pump shaft, it is engine driven. It also has an electric fan directly behind the radiator. I checked my truck out further yesterday, my temp gauge was still too high just idling in the driveway after a short one mile round trip to McDonald's. I checked the radiator fan and it was not turning at all. I pulled the rad fan relay, jumped 12 volts to terminal 30 and still the fan was dead. I had code P1491, radiator fan relay curcuit stored after that so I removed the fan shroud and plastic panel under the front of the truck to get to the wiring for the fan to check it there. What I found is a mystery to me. The fan was unplugged from its electrical connector pigtail in the wire harness under the truck. The wiring from the fan side of the connector was caught back up under the radiator and wedged between the bottom of the radiator, condenser and the metal cross member underneath the radiator cradle/lower half of the radiator fan shroud. I had to wrestle the connector plug out from under the radiator, plugged it in and lo and behold, the e-fan works again. I also jumped 12 volts and ground to the fan by itself just to be sure it was OK, which it was. Truck ran for 10 or 15 minutes in the driveway, temp gauge was normal, just a hair above the first hash mark, it always runs cool because I have a 180 dgeree thermostat. My AC is nice and chilly now too. It was so cold in my truck while it ran in the driveway that when I turned it off and got out of the cab, condensation formed on my keys and key ring. I have never unplugged or removed my e-fan. I was in a wreck last March, the body shop replaced the radiator, condenser and some other stuff up front. They had to have been the ones to leave the fan unplugged. That was their fault. It was my fault for not noticing the efan was not running all this time since the wreck. How the truck ran for 17 months with no e-fan without overheating is a complete mystery to me. I am interested in your opinions. How can I drive the truck with only the fan clutch and blade fan for cooling, no e-fan at all, run it for 17 months in summer and winter too and not overheat the engine (or worse), not even get above normal temp on the gauge? In the 105,000 miles/5 and a half years I have owned my truck, I have flushed or the coolant has been changed/flushed out 4 times. I paid to have it flushed at 60,000 miles, twice it was changed due to accidents and then I put in new coolant again when I replaced my water pump earlier this year. Maybe that is how I got away with no e-fan for this long. What do you guys here think? Thanks.

 

[rslifkin]

It should be fine with no e-fan. Most 1st gen Jeep Grand Cherokees were clutch fan only. The e-fan is probably just to make the A/C more effective when sitting at idle.

 

[Jimmy9190]

Thanks. I think on Saturday what happened is it was so hot out that the thermal spring on my fan clutch was getting a lot hotter temp off the radiator, since there was no e-fan to cool it, and that is how/why the fan clutch kept engaging that day in the heat.

 

[Hokiefyd]

I had a '97 Dakota V-8 and it had just a large mechanical fan, no electronic fan. It ran just like yours: temperature gauge at about 1/3 range normally, but would creep up some in super hot weather. You'd rarely hear the fan except for after sitting at idle for a long period, like at a long light or in a drive through. Are you running your A/C in recirculation mode? That keeps the efficiency of the A/C higher and it'll generally work better, especially at slower speeds and when stopped.

 

[sasilverbullet]

That extra fan is just that, extra for extreme cooling needs. I have the same issue here in South Texas, extremely high temps and humidity. I actually added a electric fan to my 70 Lincoln to help witht the cooling. I would make sure the body shop knows they screwed up - call the Manager. He needs to know they didn't do a good job.

 

[antonmnster]

BMWs have been set up with electric and mechanical fans for a few decades. AC performance is terrible if the electric fan doesn't work. The mechanical fan is just too small to keep up at idle to provide enough airflow over the condenser; a larger truck can get away with mechanical only because the fans are about 4x larger and move a lot of air at low speeds. Do yourself a favor and make sure your condenser is cleaned out. The other week I pulled my fan out, pulled the radiator back, and flushed out the condenser. It must have had a whole cup of dirt, sand, bugs, and leaves in it! That's bad for heat transfer.

 

[Jimmy9190]

I always run my AC in Max-Recirc mode. Down here I need all the AC I can get. The only time it is on fresh air intake is when I spray the intake cowl vents with Lysol to keep from getting mold or funky smells in my AC. It helps on that, none of the Lysol gets into the evaporator but it does keep the AC system smelling clean. As for contacting the body shop, I would rather not. I already had to go back and complain and get the at-fault driver's insurance to make the body shop replace the aftermarket front grille they used on my truck. It did not fit well at all. There were a lot of problems with the repairs from that body shop. Other than the grille I fixed them myself. If I went back now, they would laugh and run me out of their building for complaining about a job they did over a year ago. I would rather just let them be. They would not care about it anyway, so there is no point. One of the problems I had after I got my truck back from the body shop was the AC was not quite as cold as it was before the wreck. I had a good local garage evacuate and recharge it, the body shop had overfilled the refrigerant, I think by about 1/4 pound. I thought that was why it was not as cool, it was some better with the right refrigerant amount. Now I know why it was not like it should be though. The at fault driver's insurance would not reimburse me for the evac and recharge, because I did not contact them about it so the could inspect it first. I just paid the bill and tried to forget about it. Condenser is new, its front surface is clean but I will check the back side too. Thanks for the tip. Thanks for the help here.

 

[eljefino]

A fan clutch is not an on off thing and it has lots of extra capacity. It was pulling the weight of the non-op electric fan. It doesn't care that the heat it feels is from the AC or the rad, it just does yeoman's duty and gets rid of it all. It speaks well for it that it was able to maintain your under-temp thermostat temp in all but the worst conditions. I've had several RWD vehicles with both mechanical and electric fans: 99 cherokee, 83 240d, 89 volvo, 97 grand marquis. My 89 mazda 323 has port-installed AC with a pusher fan in front of the condensor that was just powered up with AC on. The puller fan behind the rad came on with the water thermoswitch.

 

[artificialist]

It isn't just RWD vehicles with this setup. The B5 VW Passat and a veriety of Audis had it as well. What made things worse was that there is almost no room to change the serpentine belt, and the path it takes is a complicated one.

 

[Hokiefyd]

Originally Posted By: eljefino

It speaks well for it that it was able to maintain your under-temp thermostat temp in all but the worst conditions.

I don't think he has an under-temp thermostat. The correct thermostat will produce a gauge reading of about 1/3 of the way up the gauge. When I first got my Dakota, I thought it had an under-temp thermostat in it, but after I replaced it during a water pump change, with one of the correct temperature, the gauge acted the same. It was correct all along, and the gauge just reads low.

 

[Jimmy9190]

Factory thermostat is a 195 degree thermostat. I use a 180 because it helps the truck have a little more power but the main reason I use a 180 is to stop engine pinging. It's a known problem on some Mopar Magnum motors. The 180 tstat tricks the PCM into thinking the engine is nver fully warmed up to normal operating temperature, so as a result the PCM will richen the air-fuel mix a bit and advance the timing just a little. This keeps the engine from pinging. Dodge had their own method of eliminating ping and eliminating an inherent engine vibration on the Magnum engines, we call it the Death Flash. It's a PCM update that retards the timing 4 degrees, and it does little to stop ping. What the death flash does do is decrease power a good bit. The death flash can not be erased, so the 180 tstat helps correct it somewhat. A 180 tstat used in conjunction with a colder heat range copper core spark plug also works to make the Magnum engines run better and eliminate pinging. Dodge did a study some years ago and found that the Magnum engines do produce more power and run more efficiently at 182 degrees, but they had to use a 195 to meet the Federal Emissions Standards. Thanks again for the help here.

 

[RiverWolf]

Originally Posted By: Jimmy9190

{snip} I am interested in your opinions. How can I drive the truck with only the fan clutch and blade fan for cooling, no e-fan at all, run it for 17 months in summer and winter too and not overheat the engine (or worse), not even get above normal temp on the gauge?

To pile on what's already been said. It works because it was probably designed to work that way and the electric fan is just helping the A/C. The 2UZ (4.7l V-8) in my 4Runner only has the single mechanical fan and I've never seen the temp gauge creep beyond normal. It even manages to do a pretty good job for the A/C in stop-n-go traffic. -Brent

 

[CBR.worm]

I have noticed in the FX that the fan clutch never seems to unlock with the AC on if the ambient temp is over about 100. Even when I am on the highway you can hear it roaring away at 3K. Once the ambient temp drops to about 95 it freewheels shortly above idle. The temp gauge never moves, and it has a seperate pusher e-fan for the A/C condenser.

 

[antonmnster]

The FX reminds me of my 84 Toyota Van. If I had the front and rear AC running on a 90+ day the fan would just scream at any speed. It robbed so much power than you had to run in 3rd gear on the highway, which was very loud. If you tried for 4th you slowly lost speed... I miss that old forklift-engine powered toaster!