A/C and my electric fan

turbobill · **Posted:** Mon May 07, 2012 3:20 pm

It got hot in central TX and I have had a problem with my A/C since it warmed up. When driving the A/C seems to work fine but when stopped the compressor cycles on and off about on 1 to 2 second intervals.

I also noticed (since my temp gauge is calibrated to Gasser specs) that I had more warming that I did last summer.

I started checking out the A/C issue and noticed that my electric fan is not running even when I have my A/C control set to 4 and full cool. Usually anytime I have my blower control set to 3 or 4 and the A/C on the electric fan would run on high.

So now I think the A/C compressor cycling when the Jeep is stopped is due to the electric fan not running. The electric fan not running is also probably why I have seen some warming up of the engine beyond normal operating temp.

I pulled the plug on the fan and verified the wiring is good and the pin two has a ground. I also jumped the power relays for high speed and then low speed operation and the fan did not run. In both cases I verified 12 v on the power pins of the fan plug. I also measure resistance between pins 1 and 2 then 3 and 2 on the fan plug and got opens in both cases. I would have thought I would have gotten a high resistance short through the fan windings but did not. I looks like I have a bad electric fan and it failed both the hgih speed and low speed operations.

Any thoughts?

papaindigo · **Posted:** Mon May 07, 2012 4:42 pm

I think you may be right that the electric fan right behind the grill has died which would certainly contribute to poor AC performance, compressor cycling (low "freon" could contribute) and possibly elevated temps especially at lower speeds or idle. That said have you checked the F2 fuse in the power distribution center to see if it's blown; I'm pretty sure that fuse is the one associated with this fan as there is no other electric "radiator fan". One easy check is to swap in the F13 window fuse as you can do without them for a check. This may not need to be checked if you had 12v downstream from the fuse at the fan plug.

I have no clue what resistance you should have gotten but I can tell you my fan runs a lot when it's hot and the AC is on.

racertracer · **Posted:** Mon May 07, 2012 6:07 pm

There was no warning when my electric fan failed and I don't know how long I was running without it when my CRD blew a head gasket.

The fan lacks an early warning device, it would be good to know when it has failed.

Check the functionality of both your cooling fans.

turbobill · **Posted:** Mon May 07, 2012 6:30 pm

Thanks papaindigo and racetracker. I have checked the fuses, in fact did what you suggested in swapping the fuses. I can understand either high or low speed going out but not both unless they are using the same winding. Since our little kluge is just that , probably what they did. I have looked at the low side pressure and it is about 100, but the compressor is not cycling so I am not sure what that means. Do you know a way to force the clutch to engage on the A/C compressor so I can check the freon?

Since the A/C is blowing cold at speed I don't think the freon could be low enough that the compressor would not engage at idle. Since the fan has controls through the PCM I thought there may be a current sensing circuit on the fan that causes the clutch to not stay engaged when idling? The A/C works normally when the truck is moving. Just a wild guess, the literature is not very clear.

Since I will be installing a fixed fan this week, I am less concerned about the electric one but it may be needed for the A/C to operate at idle.

It's a mystery.

racertracer · **Posted:** Mon May 07, 2012 6:40 pm

turbobill wrote:

Since I will be installing a fixed fan this week, I am less concerned about the electric.

The fixed blade fan is a good Modification to keep the engine cool, but when the CRD is at idle after a long drive, that is when the electric fan is most needed and it is then that the engine temps are high and heat needs to dissepate quickly.

We must make finding the issue with the electric fan failure a priority.

WolverineFW · **Posted:** Mon May 07, 2012 9:03 pm

If your electric fan is not functioning, your compressor is likely going to cycle on and off because your high pressure cut out switch will turn off your compressor when your high side pressure gets too high. With no fan moving cold air over your condenser at low speed, you have greatly reduced heat transfer capacity and will be running excessive head pressure.

When moving at speed, the wind moving over the condenser is allowing proper heat transfer, which is why your A/C is functioning when driving.

As for the fan, you are not necessarily going to get a high resistance short, as any short can easily cut the winding in the motor completely, rendering it non-functional.

Repair the fan problem first. I'll bet it fixes all the other symptoms.

galatron · **Posted:** Tue May 08, 2012 4:58 pm

Bill, as you know, I removed my mechanical fan, I will agree that the electric, and (arrgh) the mechanical fan are indeed needed for proper air conditioner performance. I say this because I was checking the pressures on my ac unit and noticed excessively high pressures at idle, but normal while driving. as stated previously this is because not enough air is passing over the condenser. So... I guess I'll be putting my fan back on. -

turbobill · **Posted:** Tue May 08, 2012 7:20 pm

Harlan, I PM'ed you. Please respond here if your CRD A/C compressor is cycling at idle. That could be a good clue as to what is going on. If yours is as well as mine is cycling then there is probably a PCM signal forcing the cycling of the compressor when the electric fan is disabled. Reving up the engine to 2000 rmp had no effect on the compressor cycling on my CRD. As soon I the Jeep starts moving as a resonable speed, 15 to 20 mph, the A/C works fine.

I have search the internet for replacement fans. Huge range of prices. It appears that the 3.7 ltr gasser and the CRD use the same fan. I have found several aftermarket sites that list a fan for both and refer to a "3 wire connector" which is what we need for the two speed fan. I am going to pull my fan tomorrow and see if there is an OEM part number on it somewhere.

Right now I have a strong suspicion that the number is CH3115143. I have found a dimensioned picture that I will also check against my fan assembly. Will post results.

papaindigo · **Posted:** Tue May 08, 2012 8:42 pm

I suspect the compressor is cycling because there is insufficient air movement across the ac condensor coil to keep reduce the coolant temp because your electric ac fan is dead. Reving the engine will have exactly zero impact unless you have Kap's fixed fan as the viscous clutch mechanical fan moves no air unless its clutch engages but the fixed fan runs all the time and might overcome the lack of an electric fan. Running the CRD down the road at a speed above 10-15 mph is probably moving enough air across the ac condensor coil to at least partially offset the lack of an electric fan.

IMHO quite chasing ghosts get the electric fan running or install the fixed fan and hope it's enough.

Caddis · **Posted:** Thu May 10, 2012 7:42 am

I've been reading this thread with interest and apologize for stealing it briefly with a couple of questions.
I too have noticed that my AC compressor cycles when at idle. It happens immediately when the engine is warm or not, if I have the AC on or either of the defrost settings, I can hear the cycling pattern while I'm stopped, and if I shut off the AC or switch to a non-defrost setting it stops almost immediately. Apparently this is not normal?
So after reading this thread it got me wondering abouy my electric fan as well, so I drove home yesterday with the AC on and fan setting 3, and noticed I got the engine temp up, (actually up to only where it's supposed to be since my tstat needs replacing), and when I parked in the yard and popped the hood, my viscous fan was running but not the electric. Can I conclude that my electric fan is defunct as well?

Joe Romas · **Posted:** Thu May 10, 2012 8:49 am

turbobill wrote:

I have search the internet for replacement fans.

The nylon fan from a 2002 KJ with towing package along with the Hyden fan clutch works very well for those that tried them.

check this thread :google:

viewtopic.php?f=5&t=65842&view=previous

Joe

turbobill · **Posted:** Thu May 10, 2012 3:41 pm

Yes, Caddis, it sounds like you have a fried fan. If you want to test it to be sure, you can pull either the high or low speed fan relays (fuse/relay box under hood in front of battery, relay locations on the lid of the fuse box) and put a jumper between pins 87 and 30. This should connect 12v directly to your fan plug, so if your fan is operational it should run. If it does not run stay tuned to this post for at least one solution to your problem.

Joe, yes I have heard good things about the Hayden heavy duty viscus fan clutch and the nylon fan from a 3.7 ltr gasser. I have chosen to go the fixed fan route as I believe it will give me better A/C operation in stop and go driving in central TX and it will provide better transmission cooling for the same driving pattern. I prefer the fan run all the time.

If I want to take a road trip when I am not towing I can pop the fan off and go "fanless".

An OEM replacement is available on line from Mopar Parts for $234 plus big shipping costs $40 or so?

I have found a two speed "Ultra Cool" Hayden fan, p/n 3814, that I believe can be retrofitted into the OEM fan shroud. The fan and fan motor can be removed from the OEM shroud by removing 3 10mm bolts, then it comes right out of the shroud.

I have ordered a fan from http://autoplicity.com, cost <$117 in my door. I will supply a post with pictures and how-to guide when I receive the fan. This fan should have the same functionality of the OEM version using all of the CRD's controls for the fan when this retrofit is complete. My CRD shouldn't see the difference between this setup and an OEM replacement. Only my pocket book will know the difference.

I found a number of aftermarket fans that can probably work with costs down to <$60, but the less expensive ones were single speed. They could be wired in and work on the CRD's controls but you would get the same operational speed when either the high or low speed relays kicked in. I am spending more just to have a dual speed motor, and a little more for Hayden than some others because of the Hayden reputation for good products. Since my OEM fan ran for 107,000 miles I would like this one to make it to at least 200,000.

papaindigo · **Posted:** Thu May 10, 2012 4:12 pm

caddis - it is worth hot wiring your AC fan to make sure it is or is not working per turbobill's post

Several things though:
1. it's perfectly normal for the AC compressor to cycle at idle when in ac mode or the defrost modes as in all of those modes the ac is "on", see owner's manual. What's not normal is for it to cycle a lot, like every few seconds.
2. it's also perfectly normal with a failing thermostat, which runs cold in the winter, to see normal operating temps once you get warmer weather and turn on the AC. Mine did exactly that until I replaced the tstat.
3. what's odd about your post is you said your viscous/mechanical fan was running but the ac one was not. Was the viscous/mechanical fan running like a bat and producing a lot of air flow or was it just sort of spinning along without moving much air? I ask because the viscous/mechanical fan should not be engaged at normal operating temp so under normal circumstances it should just sort of be spinning along. On the other hand if it was spinning like a bat and moving a lot of air it's possible, I've never heard of it, that the viscous clutch is stuck in the on postion or is coming on way to early. In either case it's possible that the viscous/mechanical fan is moving enough air under those circumstances that the ac fan rarely if ever comes on.

Worth checking your ac fan but...

Caddis · **Posted:** Fri May 11, 2012 11:16 am

Papaindigo:

I did a little more observation last night after your recent post regarding my AC, fan, etc.
You're right, the viscous fan is simply spinning, it is not actively pushing air. After watching it last night it almost seemed that the serpentine belt was moving as much air as the fan.
I still haven't seen my electric fan function, so that may require more investigation. However, I wonder since my engine is running cool anyway due to my tstat, and being here in northern MN where we're still barely reaching 70 degrees, I doubt my AC is really getting a real test right now, in fact I've only had it on to experiment with this fan stuff. Maybe the electric fan does work and it just hasn't needed to be activated yet?
After your post I don't think my AC compressor is cycling unusually.
Thanks again for all your help (and everyone else too).

papaindigo · **Posted:** Fri May 11, 2012 11:38 am

I'm not much of an AC person but I suspect that electric fan is switched to operate only if the AC condensor needs "extra" air flow to keep the various AC systems sensors "happy". If that's the case I would not expect the fan to operate all that much if any at 70F. I suspect it runs mostly in around town type driving in hotter weather and maybe on the highway in really hot (TX or AZ) weather.

WolverineFW · **Posted:** Fri May 11, 2012 4:41 pm

papaindigo wrote:

I'm not much of an AC person but I suspect that electric fan is switched to operate only if the AC condensor needs "extra" air flow to keep the various AC systems sensors "happy". If that's the case I would not expect the fan to operate all that much if any at 70F. I suspect it runs mostly in around town type driving in hotter weather and maybe on the highway in really hot (TX or AZ) weather.

Most likely correct on operation as too low a condensing pressure can reduce capacity just like too high a condensing pressure can cause issues.

turbobill · **Posted:** Thu May 24, 2012 3:38 pm

I did replace my electric fan with an aftermarket Hayden 3814. This fan provides the same operation as the OEM fan, with higher airflow. Please see my post
"How I replaced my electric fan" for the details"

I also posted additional information concerning my Fixed Fan modification. Once installed my A/C problems were completely resolved. That post is
"My Fixed Flex Fan Mod"

SteamDonkey · **Posted:** Mon Jan 12, 2015 10:50 pm

Follow up question to Turbobill's relay testing advice above. I'm troubleshooting a fan that does not come on with a/c engaged and jumping pins 87 and 30 on both the high and low relays brings the fan to life. But here's what I don't understand: simply pulling either relay out (with key in the run position) also turns the fan on. I've pored over the wiring diagrams and haven't the slightest idea how or why this would happen. ????

flash7210 · **Posted:** Mon Jan 12, 2015 10:58 pm

Sounds like your fan is working and the relays are good.
I dont know where you live but it might be too cold outside to active the fan. Even with the AC on.
Check your freon level and pressures. If the AC pressures switches dont see enough pressure the fan wont come on.

SteamDonkey · **Posted:** Tue Jan 13, 2015 12:24 am

Definitely too cold to active them (interior Alaska) based on ambient temp but it hasn't been clear to me from the FSM whether they shouldn't just come on automatically for a minute, regardless of temp, when a/c is activated. Kind of academic anyway as I am mostly just trying to verify the electric fan in general as I run without a viscous fan in the subzero here but want to know it would kick in in a warm spurt. Still an all, why the heck would pulling a relay *activate* them? Really don't get that.

A/C and my electric fan

Who is online