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Unread 06-28-2013, 04:39 PM   #1
BigJohn96ZJ
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using a/c makes my jeep run hotter?

So i recharged my a/c last week and been using it since its 95+ outside. But it makes the jeep run at a little over 210 which is too hot for my liking. It stays at 180-190 without the a/c on. I just replaced the water pump and thermostat (180) aswell. What can i do to keep it cooler?

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Unread 06-28-2013, 04:51 PM   #2
WhiteOut
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New rad, flush the system and make sure there is no air in the system.
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Unread 06-28-2013, 05:34 PM   #3
a70eliminator
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The a/c condenser when active is running has a design temperature of 30 degrees over ambient. Example- 70 degrees outside temp the condenser temp is about 100 degrees, if it's 95 outside then the condenser is running about 125 degrees. The condenser it situated right in front of the radiator so doesn't help that's for sure but where else you going to put it, it needs airflow that's real important.
With a 15psi cap you should be good to well over 210 my 5.9 lately with ac on is hitting 210 on a hot day.
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Unread 06-28-2013, 05:47 PM   #4
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mine is always right at the middle marking, so thats where i like it to sit and assume it is normal
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Unread 06-28-2013, 05:49 PM   #5
Candymancan
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its a known fact running the a/c makes the engine warmer...
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Unread 06-28-2013, 06:28 PM   #6
BigJohn96ZJ
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Thanks for all the input guys. It had a new rad 2 years ago. Im just dont like my motor running that hot. It hard starts and is a total dog when it gets that way. So i guess im having to choose Between cold a/c and jeep running normal.
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Unread 06-28-2013, 06:33 PM   #7
a70eliminator
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The a/c drains about 4hp from your engine, so yea it can make a noticable difference on how much you have to push on the skinny pedal, I can feel right away if my a/c is on, the extra drag may be what your feeling and it's not temperature related.
But again if your in need of tune up, running the a/c will certainly drive it over the top.
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Unread 06-28-2013, 07:00 PM   #8
JBrady5555
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Mine drops from 14 volts to 12-13 when I turn on the a/c. is that normal?
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Unread 06-28-2013, 07:26 PM   #9
coralman
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You are getting rid of the heat of compression, the heat inside the cab, before you even begin talking about ambient temperaure so yeah it may run a bit hotter. Some things you could check are to remove the upper radiator support and check for crap trapped between the radiator and condensor. It often has bugs, leaves and general crud there. My 4.0, sits at probaly { with guesstimate gauges} 195 with A/C off and 210 with it on. Check the condition of the end baffles on the radiator to make sure you aren't bypassing air. As Whiteout said make sure the cooling system is clean. Is the A/C charge correct? Is it cooling to your liking? The temps you are desribing aren't that out there.
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Unread 06-28-2013, 07:32 PM   #10
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Quote:
Originally Posted by BigJohn96ZJ View Post
So i recharged my a/c last week and been using it since its 95+ outside. But it makes the jeep run at a little over 210 which is too hot for my liking. It stays at 180-190 without the a/c on. I just replaced the water pump and thermostat (180) aswell. What can i do to keep it cooler?
Flush the system, change the coolant, don't use the aircon so much.

The aircon results in an increased electrical loading (fan, compressor clutch, cooling fan,) which increases engine loading.

Driving the compressor proper results in increased engine loading.

And, the aircon condenser is usually in front of the radiator core - which increases THERMAL loading by reducing heat rejection capacity of the system.

There are a few things you can do to pull your operating temperature down while running aircon (dumping in a bottle of Water Wetter certainly won't go amiss, either!) but your operating temperature will almost invariably rise a bit with the aircon on - simple physics.
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Unread 06-28-2013, 08:50 PM   #11
BigJohn96ZJ
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Well it did it again tonight at work. turns out the whole getting way too hot thing is cuz my friend that was there with me changing my water pump filled it up with only water!! Hence NO ANTIFREEZE!! It was sitting on his carport floor unopened where i left it a week and half ago. It wasnt just hot it was boiling in the reservoir.
Needless to say ill be doing a coolant flush in the morning and adding water wetter too. Thanks alot guys.
Ill be posting back if it doesnt fix it.
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Unread 06-28-2013, 08:55 PM   #12
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Actually.. Plain water cools better then antifreeze does... Antifreeze is just that... ANTI FREEZE.. its also to keep the metals in the system from corroding and from the system boiling plain water boils at like I think 212-220f ? Or something like that and with antifreeze it brings it up to around 260.... Other then that when you are in a very hot area like say Arizona its better to have a 70% water 30% antifreeze solution because water cools faster then antifreeze does..

Drain it for one because he probly used a garden hose to fill it up and you probably have all kinds of minerals now in the system which can cause calcium build ups.. You need to use distilled water.. They sell gallon jugs in the store for like 90 cents.. buy a bottle of pure antifreeze and mix it 50/50 yourself.. Buy one of those $10 gauges from the auto parts store.. they measure the mixture and tell you how cold it will get till it freezes and how hot till it boils.
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Unread 06-28-2013, 09:17 PM   #13
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Antifreeze/COOLANT raises boiling point, without it some boiling within the internals of the engine in the hottest places like combustion chambers and cylinder walls is eminent, water boils at roughly 240 @10psig pressure cap, the combustion chambers can run 5-600 degrees so water will flash off to steam under direct contact, water is the best heat transfer fluid under the right conditions but inside your engine isn't one of them, Antifreeze/coolant is a must have.
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Unread 06-29-2013, 11:08 PM   #14
BigJohn96ZJ
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This morning i went to oreillys with a friend and bought some coolant and water wetter.when i got home i ran the jeep up to temp took the hose and put it in the rad and pulled the drain plug on the bottom to flush out all the old water. Then after it was clear i plugged it back up and filled it up. Ran great and was at a normal temp all day but i forgot to turn on the a/c. Oops
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Unread 06-30-2013, 01:52 AM   #15
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Quote:
Originally Posted by a70eliminator View Post
Antifreeze/COOLANT raises boiling point, without it some boiling within the internals of the engine in the hottest places like combustion chambers and cylinder walls is eminent, water boils at roughly 240 @10psig pressure cap, the combustion chambers can run 5-600 degrees so water will flash off to steam under direct contact, water is the best heat transfer fluid under the right conditions but inside your engine isn't one of them, Antifreeze/coolant is a must have.
Er - "flash temp" in the combustion chamber is closer to 1600-1800*F, just so you know...
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