Jeep overheats only when A/C is on, cant figure out why

bench10

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Hey guys first time posting but i have been here in the forum for awhile, decided to ask here since I've found a lot of good info when i wanted to lift my Jeep (2.5 OME Lift) , but i can't seem to find answers to this problem i have, so as mentioned in the title i have an overheating issue on my 2005 Jeep Liberty Renegade with about 175k miles and it doesn't have the heavy duty cooling system. This only occurs when ac is on, at idle, so when I'm driving the jeep stays cool. This only started happening just recently since the weather started getting to the higher 90°F to 100°F here in northern California. Here's a list of things I've already done to the Jeep before it started overheating

Just did a coolant flush a couple of months ago and it had Peak long life universal 50/50. got all the old stuff out with a flush and distilled water and afterwards i installed a thermostat i bought from Napa and used Zerex HOAT coolant 50/50 mix, no leaks since I've done it. I burped the system but did it again yesterday since it seems like i missed a couple of air bubbles, still overheats

Replaced electric Cooling fan recently and whenever the ac is on that also turns on and it's pretty loud and gives out good airflow

Last year i replaced radiator and coolant reservoir since they were both leaking, and while i was at it i replaced both hoses

Water pump was replaced about 4 years ago, could be a possible culprit.


That's pretty much all I've done to the cooling system and i haven't touched anything on the ac compressor nor condenser. I've also noticed that the ac never cycles off, and whenever i start the car i hear a clunking/clicking noise that only disappears if i turn off the ac, i have video of it if anyone needs it

I checked the ac clutch relay and they seem to be working, I also checked the low side pressure of the compressor to see if freon needed to be added but it had a good reading, but im not able check high side though

What should else should i do to diagnose my issue? I am completely loss and any help would be great.

And by overheating, i mean the temp gauge would go pass the 3/4 mark. I did a little test with the ac on and according to my obd reader, normally when driving it reads 205°-210°F and when idle, it would creep up passing 230°F and a/c starts blowing warm, then i turn off the ac, and temp slowly goes down to about 210°F or less

Hope this information helps anyone who knows how to deal with this type of overheating issue and if anyone needs to know more about whats going on, just let me know.
 

tommudd

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NAPA thermostat , NO
MOPAR thermostat YES

first thing

Plus if it had that crap antifreeze in it would be tough to completely get all of that without a power flush
 

bench10

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NAPA thermostat , NO
MOPAR thermostat YES

first thing

Plus if it had that crap antifreeze in it would be tough to completely get all of that without a power flush
Putting in a mopar thermostat would be a good idea, Ill keep that in mind then next time it needs a flush but at the moment it seems like the thermostat is doing what its designed for and coolant is still pretty clean. Unless there’s something im missing?
 

DadOSix

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Hey guys first time posting but i have been here in the forum for awhile, decided to ask here since I've found a lot of good info when i wanted to lift my Jeep (2.5 OME Lift) , but i can't seem to find answers to this problem i have, so as mentioned in the title i have an overheating issue on my 2005 Jeep Liberty Renegade with about 175k miles and it doesn't have the heavy duty cooling system. This only occurs when ac is on, at idle, so when I'm driving the jeep stays cool. This only started happening just recently since the weather started getting to the higher 90°F to 100°F here in northern California. Here's a list of things I've already done to the Jeep before it started overheating

Just did a coolant flush a couple of months ago and it had Peak long life universal 50/50. got all the old stuff out with a flush and distilled water and afterwards i installed a thermostat i bought from Napa and used Zerex HOAT coolant 50/50 mix, no leaks since I've done it. I burped the system but did it again yesterday since it seems like i missed a couple of air bubbles, still overheats

Replaced electric Cooling fan recently and whenever the ac is on that also turns on and it's pretty loud and gives out good airflow

Last year i replaced radiator and coolant reservoir since they were both leaking, and while i was at it i replaced both hoses

Water pump was replaced about 4 years ago, could be a possible culprit.


That's pretty much all I've done to the cooling system and i haven't touched anything on the ac compressor nor condenser. I've also noticed that the ac never cycles off, and whenever i start the car i hear a clunking/clicking noise that only disappears if i turn off the ac, i have video of it if anyone needs it

I checked the ac clutch relay and they seem to be working, I also checked the low side pressure of the compressor to see if freon needed to be added but it had a good reading, but im not able check high side though

What should else should i do to diagnose my issue? I am completely loss and any help would be great.

And by overheating, i mean the temp gauge would go pass the 3/4 mark. I did a little test with the ac on and according to my obd reader, normally when driving it reads 205°-210°F and when idle, it would creep up passing 230°F and a/c starts blowing warm, then i turn off the ac, and temp slowly goes down to about 210°F or less

Hope this information helps anyone who knows how to deal with this type of overheating issue and if anyone needs to know more about whats going on, just let me know.
My money is on low flow caused by bad water pump.

At road speed, with a/c either state, the engine runs cooler than idle with ac on due to that massive air flow thru the radiator.

There has been discussion on the poor impeller design on these pumps. Also, mopar stat, the right way in, with bleeder at the top.

Post up the start noise video. Sounds interesting!
 

tommudd

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^^^^^ this
Plus while many parts maybe new or fairly new does not mean they are working properly
Many new parts are not designed well in the world anymore which leaves to issues
One being cheap thermostats,
another being plastic water pump propellers
The main things I look at when someone brings in their KJ to me with symptom's such as yours is Thermostat, and then Water Pump
sometimes next is the cap
Both maybe brand new but means zip to me
 

JeepJeepster

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Overheating at low speeds is typically an air flow issue. Do you know if it has a two speed fan? Is the high speed working?
 

bench10

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My money is on low flow caused by bad water pump.

At road speed, with a/c either state, the engine runs cooler than idle with ac on due to that massive air flow thru the radiator.

There has been discussion on the poor impeller design on these pumps. Also, mopar stat, the right way in, with bleeder at the top.

Post up the start noise video. Sounds interesting!
Good to know then! Any recommendations on what water pump i should use? OEM? I'll probably order it and a Mopar thermostat and put in new coolant

^^^^^ this
Plus while many parts maybe new or fairly new does not mean they are working properly
Many new parts are not designed well in the world anymore which leaves to issues
One being cheap thermostats,
another being plastic water pump propellers
The main things I look at when someone brings in their KJ to me with symptom's such as yours is Thermostat, and then Water Pump
sometimes next is the cap
Both maybe brand new but means zip to me
I'm going to live by these words now, and I'm pretty sure the pump i bought was plastic, it was an AC Delco part i bought when i didn't know much about cars
Overheating at low speeds is typically an air flow issue. Do you know if it has a two speed fan? Is the high speed working?
It's a two speed fan, i haven't tested the high speed yet. All what i know is that it turns on right away. How should I test that before i buy anything else? Also yesterday i tried letting it idle while it was a bit cooler outside (85°F) with ac on and it didn't overheat,
 

bench10

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Here's the ac video and it was after i already started it, so i started off by reving it without the ac then i turned on the ac and did the same thing
The noise is a lot louder when starting then it slowly disappears, i can even hear the noise when I'm inside the Jeep, I'll try recording that again later today

 

JeepJeepster

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I'm not sure how the 05 Libertys work, but I know my 04 just has low & hi speed fan relays that are controlled by the PCM, very simple. Certain year liberty's (02-some 03's?) had a solid state relay under the battery. I'm not sure when the high speed kicks on (I want to say 230F) but I know my low speed always kicked on at 218F if I didnt have the A/C on. Its never kicked on since adding the HD cooling unless the A/C is on or the trans is getting too warm.

Easiest way would to be just listen, you should be able to hear when the high speed kicks on. I'm honestly not sure if my high speed has ever kicked on, but my engine has never been above 218F. Even idling and/or towing in 90F before I added the HD cooling.

Heads up, the 3.7 DOES NOT take well to overheating.
 
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bench10

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I'm not sure how the 05 Libertys work, but I know my 04 just has low & hi speed fan relays that are controlled by the PCM, very simple. Certain year liberty's (02-some 03's?) had a solid state relay under the battery. I'm not sure when the high speed kicks on (I want to say 230F) but I know my low speed always kicked on at 218F if I didnt have the A/C on. Its never kicked on since adding the HD cooling unless the A/C is on or the trans is getting too warm.

Easiest way would to be just listen, you should be able to hear when the high speed kicks on. I'm honestly not sure if my high speed has ever kicked on, but my engine has never been above 218F. Even idling and/or towing in 90F before I added the HD cooling.

Heads up, the 3.7 DOES NOT take well to overheating.
I'll do that then, I'll swap some relays too just to see if the high speed turns on

Also i noticed you added the heavy duty cooling system, would that be something anyone could do, or is it a bit complicated to pull off? Im doing some light towing atm but if i could tow a bit more that would be great.
 

DadOSix

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Here's the ac video and it was after i already started it, so i started off by reving it without the ac then i turned on the ac and did the same thing
The noise is a lot louder when starting then it slowly disappears, i can even hear the noise when I'm inside the Jeep, I'll try recording that again later today

Listening, i only hear it when ac is on. Says to me - possible a bit overcharged - or a marginal compressor.
 

bench10

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Listening, i only hear it when ac is on. Says to me - possible a bit overcharged - or a marginal compressor.
The ac compressor hasn't been serviced, so I'm assuming i would have to have someone vacuum and recharged, and, if i have to, replace the whole thing? Would it be possible that the ac itself can cause the overheating? I'm going to check the fan to see if the high speed is working first and see what I'll do afterwards
 

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The ac compressor hasn't been serviced, so I'm assuming i would have to have someone vacuum and recharged, and, if i have to, replace the whole thing? Would it be possible that the ac itself can cause the overheating? I'm going to check the fan to see if the high speed is working first and see what I'll do afterwards
I don't see the compressor as overheating your jeep unless when the ac kicks in, it puts much extra load on the engine. If the compressor failed to the point of locking up, you would likely snap the serpentine belt, and maybe have a locked up clutch.

That rattle could also be a weak compress clutch that 'chatters'.

To service a/c - you (r) tech would need gages and a recovery and recharge unit.

If you are familiar with the system, you can tell with the gage readings if the system is overcharged as ell as low. It is possible to overcharge with those kits sold in auto parts stores, etc.

But still - would not be likely to cause an overheat.
 

bench10

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I don't see the compressor as overheating your jeep unless when the ac kicks in, it puts much extra load on the engine. If the compressor failed to the point of locking up, you would likely snap the serpentine belt, and maybe have a locked up clutch.

That rattle could also be a weak compress clutch that 'chatters'.

To service a/c - you (r) tech would need gages and a recovery and recharge unit.

If you are familiar with the system, you can tell with the gage readings if the system is overcharged as ell as low. It is possible to overcharge with those kits sold in auto parts stores, etc.

But still - would not be likely to cause an overheat.
I haven't charged it up at all but I'll have someone who has gauges help me check the ac system.
Yeah it only overheats when ac is on while idling, any other time Jeep runs fine and driving (30mph+) with ac on doesn't cause overheating. Both speeds for the fan also work. So at this point I'm guessing water pump will be our culprit and I'll replace that and the thermostat for once with a Mopar part.
 
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JeepJeepster

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Does your Jeep have a small or large fan shroud? If it has a large fan shroud, you will not be able to touch the oil filter from the top side. For some reason, most 04's already came with the bigger fan shroud, so all I had to do was add the clutch and fan, very easy. I most recently found out that the HD cooling MIGHT have also included a larger transmission cooler, but I've not verified that.

No, the AC cannot directly overheat the engine.
 

bench10

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Does your Jeep have a small or large fan shroud? If it has a large fan shroud, you will not be able to touch the oil filter from the top side. For some reason, most 04's already came with the bigger fan shroud, so all I had to do was add the clutch and fan, very easy. I most recently found out that the HD cooling MIGHT have also included a larger transmission cooler, but I've not verified that.

No, the AC cannot directly overheat the engine.
I'm able to touch the oil filter and the fan shroud is pretty small. But if it's just adding that then I'll look more into it and I'll try to pull it off.

But thank you guys for your input, I'm going to buy a Mopar water pump and thermostat and hope they work
 
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bench10

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Bit of an update, water pump was the culprit, when i took it out, it felt A LOT more looser and had a squeak noise compared to the Mopar water pump i bought. And it had a bit of rust on the propeller, and I'm sure that's not a good sign.

The Mopar thermostat i bought didn't even arrive and I'm pretty sure it's not even shipped yet, and nobody local had one so i tested the thermostat i already had and dipped it in boiling hot water, opened and closed just fine, so i installed it but i will probably replace it in the near future (if the part even arrives), I'm in a pinch since I'm heading camping tonight and I'm taking this jeep.

Anyway the jeep was running at idle on a hot day and was at 237°F with ac on, took it more than 30mins to get there instead of 10mins before the fix. Didn't move any higher than that and ac blew cold. While driving it was at 205°-210° so all is good now. Thanks guys for your help i really appreciate it!
 

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