07 Liberty overheating, so far only with a/c on?

incucrash · **Posted:** Tue May 24, 2011 2:02 pm

07 Liberty, 3.7L

A few months ago I noticed my jeep temp was almost in red while idling with ac on. Shortly after I changed bad water pump and radiator cap. Problem solved? no! it has happened twice
since, fan was on with ac on, but maybe it is cutting off/on?

Any ideas?

liquidxit2 · **Posted:** Tue May 24, 2011 2:34 pm

Im assuming you did a thermostat and full fluid change as well.

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

^^^^^
x2
Plus not only that you need to use HOAT coolant and get all of the air out of the cooling system.

liquidxit2 · **Posted:** Tue May 24, 2011 10:58 pm

BugginKJ wrote:

^^^^^
x2
Plus not only that you need to use HOAT coolant and get all of the air out of the cooling system.

Yeah I usually run the vehicle for a while with the cap off and the heat on full blast. Systems usually take 15-30 min to burp fully and even then I check over the next few days as they surely need a top off.

incucrash · **Posted:** Wed May 25, 2011 7:24 am

Used Mopar coolant for vehicle, did not change thermostat but the issue had only happened 3 times, unable to reproduce last night. Seems like on humid days, with ac on only when idling, moving slow? Fans moving alot of air and coming on.
I used a 8mm allen and undid screw on top radiator hose to bleed air, there was air after water pump install, but yesterday none.
Ill do the burp technique of topping off and letting run.

Ill probably change tstat and top off, burp her like a baby

Any Suggestions for upgraded fans and radiators ?

liquidxit2 · **Posted:** Wed May 25, 2011 10:23 am

If the system is burped fully, new working thermostat, correct fluid and the fan is working 100% the only thing I would say at this point is a bad coolant temp sensor or there may be a blockage in the system. Leaning more towards the sensor as a blockage would cause issues all the time.

incucrash · **Posted:** Thu May 26, 2011 8:42 am

The fan comes right on with ac on, blowing good.

Each time that its happened, the ac cycles and blows warm, then temp goes up.

I think thermostat would be causing it to overheat more? I can change it, any recommended brand and model? I like my stuff from napa, but wondering whats best?

The hoat coolant from napa was added with mopar and distilled, maybe after tstat, flush and use all same coolant.

I thought sensor but once I started driving, turned heat on, it went down, so I think its reading right.

ill try update solution if I find it.
Thanks for help everyone

liquidxit2 · **Posted:** Thu May 26, 2011 2:53 pm

I wouldnt reuse the coolant. Too much opportunity to get contaminants in it when draining.

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

Thermostat from NAPA is fine but while it is out I would do a complete system flush of your cooling system then install your thermostat using ONLY HOAT coolant. Bleed air properly and your problem should go away.

incucrash · **Posted:** Fri May 27, 2011 6:01 am

Ok, ill see what happens. I never would reuse... I getting the coolant at napa for half off compared to mopar stuff.

Where is a good place to plug up the prestone flush on liberty?

jimymc · **Joined:** Thu Dec 17, 2009 7:51 pm **Posts:** 248

When you say that the fan is blowing do you mean the inside fan that blows in the cab or are you talking about the radiator cooling fan? I had this problem and it was an intermittent radiator fan. A loose connector at the fan was making contact sometimes and not others. I replaced the fan and the relay before I realized that it was the connector. A little tweeking of the connector and everything is fine now.

jimymc · **Joined:** Thu Dec 17, 2009 7:51 pm **Posts:** 248

When you say that the fan is blowing do you mean the inside fan that blows in the cab or are you talking about the radiator cooling fan? I had this problem and it was an intermittent radiator fan. A loose connector at the fan was making contact sometimes and not others. I replaced the fan and the relay before I realized that it was the connector. A little tweeking of the connector and everything is fine now.

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

incucrash wrote:

Ok, ill see what happens. I never would reuse... I getting the coolant at napa for half off compared to mopar stuff.

Where is a good place to plug up the prestone flush on liberty?

I would never use one of those Prestone flush things, they never flush the system properly. Take it to a radiator shop and have a proper power flush done OR if ya don't want to take it to a radiator shop, remove your thermostat, reinstall neck/hose, fill your system with water, turn your heater on and run the engine for a time. Drain the water and repeat untill the water comes out clean, I would suggest cleaning out your coolant resevoir also. Then install the new thermostat and fill with HOAT coolant, bleed the air then top off. Doing it that way is much better than a gimmick flush "t" if you don't want to pay to have a proper power flush done. My :2cents:

KJ_Dave · **Posted:** Fri Jun 03, 2011 8:02 pm

The problem is the thermostat. Your test by turning the heater on proved it. The reason is your tstat failed in the closed position, not allowing coolant to flow to radiator. The heater core is just a small radiator allowing the heat exchange to occur. Go to Napa and get a fail safe one that when it fails it does so in the open position to allow the coolant to flow freely. Factory ones are not like that.

incucrash · **Posted:** Sun Jul 24, 2011 9:41 am

With this heatwave, I was able to duplicate the issue.

I was going down interstate, ac on. Temp gauge sitting normal.
Within 3 minutes of coming off at a red light, needle started going up.

Was able to pop hood, fan barely turning.
spun fan later, spins ok, swapped blower motor relay with rad fan relay, both same p/n, both worked fine. probably mental but fan seemed stronger with swapped relay?

on 2007, I have a fuse and relay box, is there an external relay or is that only older liberties?

Im leaning towards coolant temp sensor, but why only when ac is on? Just from making engine work harder?

A thermostat would cause issue to happen always, not just when ac is running going slow,

jimymc · **Joined:** Thu Dec 17, 2009 7:51 pm **Posts:** 248

I can't speak for your newer model, but the the older Liberty's have a fan relay that is mounted below the battery on the wheel well. The wiring diagram shows that it is controlled by the PCM which looks at several things such as the engine temperature sensor and whether the AC is on to decide to turn on the radiator fan. When you turn on the AC the radiator fan should also come on. The PCM is programmed to do that even if the engine is cold. When you are going down the road at a speed above about 35 mph there is enough air going through the radiator to properly cool the engine. It is when you are going slowly that you really need the radiator fan, particularly when it is hot and you have the AC on. I replaced the fan and the relay on mine, before I found that one of the problems was a faulty connector to the fan. I believe that the radiator fan was going bad too. Like yours, I could turn it by hand and it seemed to be OK. I did hear a slight grinding like bearing noise, but I guess it had to get hot before it failed. You might want to wire the fan directly to the battery and see if it will run OK without the sensors, PCM and relays. If the fan runs OK this way then it is something else like a fuse, relay or engine heat sensor.

incucrash · **Posted:** Mon Jul 25, 2011 11:53 am

fan comes on when cold and ac on.

Its just when shes hot and humid causing fan to move slow.
Dont know where to start

JL Rockies · **Posted:** Mon Jul 25, 2011 1:42 pm

I've had the same problem since day one. My solution was buying a 4Runner. I'm in Moab right now and let me tell you, it's such a pleasure to drive around without the heat on!

incucrash · **Posted:** Tue Jul 26, 2011 10:26 am

what did you change? Beem eyeballing a yota, are the 4 runner engines interference?

incucrash · **Posted:** Mon Aug 01, 2011 4:12 pm

jeep doing fine with cooler temps....
ran the a/c today for about an hour off and one driving around...

anyone suggest some things to try?

I wished they made the heavy duty fan kit...*&^^&*

07 Liberty overheating, so far only with a/c on?

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