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Possible cooling fan problem?


 
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MAJ
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Joined: 03 Aug 2007
Location: Baltimore, MD

PostPosted: Fri Aug 03, 2007 5:38 pm    Post subject: Possible cooling fan problem? Reply with quote

Hi All,

I had my first couple of problems with my cherokee, which lead me here to my first post. I have 2000 Cherokee, 4.0L.

My questions is, should the electric radiator cooling fan come on when A/C is on? Mine does not. It only comes on when the coolant temp gets high (above ~88 C). If it should, what would be the most probable cause of this...relay, wiring?

I got into this because earlier today the jeep started vibrating in a pretty weird way, so I panicked and just brought it to the shop to get it checked out. They told me the fan relay burned up, which caused the fan to stay on all the time, which eventually burned up the fan motor...it sounded a little bogus to me so I drove it home and started poking around. I found that the fan actually cracked, which would explain the vibration.

So now I'm trying to troubleshoot the relays to see if there is anything else wrong. Like a said earlier, the fan kicks on when coolant temps get high, but no when the A/C is on.

Thanks in advance for the help.
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Brad The Best
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Joined: 14 Jan 2007
Location: Kamloops B.C Canada

PostPosted: Sat Aug 04, 2007 10:00 pm    Post subject: Reply with quote

look at the prongs on the relay are they all blue ?

does your ac work ?

sounds like the shop wasn't really yanking your chain thats a perfectly good explanation except for the fact that it turns on when its hot . have you actually went out and look at it spinning or does it just sound like its on ( could be clutch fan making all the noise )

kicks in at 88C ? hmm mine doesn't , it kicks in at higher then that . or maybe mine is just messed up .
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MAJ
Member


Joined: 03 Aug 2007
Location: Baltimore, MD

PostPosted: Sun Aug 05, 2007 5:40 am    Post subject: Reply with quote

In terms of relays, i'm guessing the only relay of concern is the cooling fan relay. I checked all the relays and they look perfectly fine.

I know for certain the fan is causing the vibration...i stood over the hood and watched the fan kick on as the whole front end started vibrating. So I bought a new fan yesterday, installed it, and no more vibration. When I bought the fan, one of the mechanics said the fan will kick on when the a/c system reaches a certain pressure, not as soon as the a/c is on. And you are right about the 88 C...i think it's more like 100 C.

As for my a/c, it's definitely an issue. for starters i've got leaks somewhere because i have to charge it now and then to keep it cold. What's weird is it will stay cold for about 20 minutes and then start blowing cool, but very humid air. So I haven't really checked into this problem yet.
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Teriod
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Joined: 19 Jun 2007
Location: California

PostPosted: Sun Aug 05, 2007 8:38 am    Post subject: Reply with quote

a poor working ac will definitly affect the operation of the fan, and eventually the heat of the engine will force the fan to come on, the mech was right in assuming the relay was the cause, but it probably has further problems with the ac not working properly
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ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Sun Aug 05, 2007 10:06 am    Post subject: Reply with quote

MAJ wrote:
When I bought the fan, one of the mechanics said the fan will kick on when the a/c system reaches a certain pressure, not as soon as the a/c is on.


Not exactly, but close. Once the clutch on the A/C compressor kicks in, the electric fan kicks on. The clutch will not kick on unless there is a minimum low side pressure. So the electric fan and A/C system pressure are related, but not directly.

As stated above, a poor charge on the A/C will cause the compressor to engage and disengage constantly, which will cycle the the fan on and off, which can eventually burn out the relay. If you fix the A/C problem, the electric fan/relay issues will probably clear up. Wink
_________________

97 XJ Sport with a bunch of stuff
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Never argue with idiots, they drag you down to their level and beat you with experience
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MAJ
Member


Joined: 03 Aug 2007
Location: Baltimore, MD

PostPosted: Sun Aug 05, 2007 1:54 pm    Post subject: Reply with quote

Phantum, thanks for clearing up the cooling fan and a/c relationship.

when i turn on the a/c, the clutch engages and i get cold air...the pressure on the low side stays at ~35 psi which i think is plenty. the cooling fan, however, does not come on until the coolant temp is ~100 C. i bought a new cooling fan relay for the heck of it, and same results. and since the a/c clutch is engaging, then the a/c clutch relay must be okay too.

so, if the a/c clutch kicks on, but not the fan, is it most likely just faulty wiring or is there another relay/switch/fuse that could be interrupting things?

thanks everyone for all the info.
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Brad The Best
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Joined: 14 Jan 2007
Location: Kamloops B.C Canada

PostPosted: Sun Aug 05, 2007 3:33 pm    Post subject: Reply with quote

you said you had some leaks , thats the first thing you want to fix .
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Cherokee00
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Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Thu Aug 09, 2007 12:16 pm    Post subject: Reply with quote

With the exception of a non-cracked fan and no confirmed a/c leaks, I have EXACTLY the same symptoms on my 2000! Cherokee

If A/C really is ok, I end up with the conclusion that A/C pressure sensors or ECU is the problem.

Anyway, I will have the car checked by a A/C expert tomorrow. Letīs see if he solves this problem.

Will share all findings..

/Fredrik (Stockholm, Sweden)
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Cherokee00
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Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Fri Aug 10, 2007 1:06 pm    Post subject: Reply with quote

OK. A/C expert has given his verdict.

Causes;

1) Pressure sensor (high pressure side near compressor) not working properly

2) Compressor clutch worn. Clutch operation becomes intermittent when hot

Problem one was solved easily and el. fan is now triggered by both A/C pressure and engine temp.

Problem two is requiring either new clutch or shim adjustment of present clutch, depending on amount of wear. This operation is not difficult in itself but requires special tools so I canīt do it myself :-(

Regards,

Fredrik
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MAJ
Member


Joined: 03 Aug 2007
Location: Baltimore, MD

PostPosted: Sun Aug 19, 2007 6:17 pm    Post subject: Reply with quote

Hi Fredrik,

I've been away from the forum for a little while, and was very interested to see your posts. I wanted to follow up to see if you had the a/c clutch repaired/replaced, and if so did it fix the problem?

Also, when you said you were experiencing the EXACT same problems, did you also experience the scenario where you get cold a/c for about 20 minutes and the it starts blowing warm air?

Thanks.
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Cherokee00
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Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Tue Aug 21, 2007 12:13 pm    Post subject: Reply with quote

Hi,

Iīm still stuck with a non-functioning AC. I am also getting more and more irritated over AC-repair shops and their lack of interest to REALLY solve a customerīs problem.

The first A/C garage I went to concluded that the problem was the clutch but wanted to replace both clutch and compressor because "it was easier". The mechanic didnīt seem to care that it would be more expensive for me (and that he would throw away a functioning compressor).

I contaced a few other repair shops of which one said that they could repair the existing clutch. Good! Consequently. I turned in the car to this shop for clutch repair.

When the mechanic called me in the afternoon he told me that he had not repaied the clutch but pressure tested the system and filled it up. This was something that had already been done by the first repair shop which I obviously had told this second mechanic. Anyway, the mechnic told me that the fill up had fixed the problem and that I could now fetch the car.

I actually fetched the car this afternoon and went for a short ride to test it. Problem NOT solved! After 15-20 minutes warm and humid air starts to flow from the outlets. Just as on your car.

I still beleive that something is wrong with the clutch. To eliminate that there is something wrong with the computer (or relay) I checked that 12 V was feeded to the clutch with engine running and non-functioning AC. It was. No electrical errors, it seems. Electrical fan is also functioning.

Clutch is supposed to keep going for 200.000 km while compressor should stand 350.000 km before failure (all according to A/C repairman). Searching the internet I have found three owners describing this problem. All cars concerned are 1999 or 2000 XJīs. Could there be a clutch manufacturing problem these years?

Will visit repairshop tomorrow again. So far, this has costed me 4000 Swedish Kronor (600 USD) and absolutely no progress has been made. I will probably not very polite...

Brgds,

Fredrik
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BTO
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Joined: 24 Aug 2007
Location: MO

PostPosted: Mon Aug 27, 2007 7:39 pm    Post subject: Reply with quote

Any new findings to report Fredrik? My '96 XJ is experiencing similar problems with overheating when AC is on.
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Cherokee00
Member


Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Fri Aug 31, 2007 10:34 am    Post subject: Reply with quote

Hi BTO,

No news yet, but the car will be re-checked by the a/c repairshop next week. I will keep you posted.

Brgds

Fredrik
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Cherokee00
Member


Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Tue Sep 04, 2007 11:18 am    Post subject: Reply with quote

Hi, all A/C fans Wink

Latest news;

The A/C garage has now checked the car again. It has - once again - been concluded that the system is leak-free.

The latest theory is that the engine temperature sensor is faulty. The logic behind this theroy is that if the engine temperature sensor signals that engine is overheating, it shuts off uneccesary load, such as the ac system.

If this is correct, it is good news. Replacing the tempsensor is a cheap job. But I am not sure they are right. According to Jeepīs service manual, there is no function that switches off loads when engine is overheating (or, as in this case, when the computer thinks so due to false signal from faulty sensor).

This seems to be a never ending story....

Brgds,

Fredrik
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Cherokee00
Member


Joined: 09 Aug 2007
Location: Stockholm, Sweden

PostPosted: Tue Sep 04, 2007 11:47 am    Post subject: Reply with quote

...and if the computer gets a signal that the engine is overheating, wouldnīt that mean that the electrical fan would be running constantly?. It doesnīt..
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