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2004 Liberty A/C Not Cold Enough
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rick59
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Jul 7, 2010, 10:14 PM
Post #1 of 11
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2004 Liberty A/C Not Cold Enough
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2004, Jeep, Liberty, 3.7L V6, 108K,
Air conditioner not cold enough.
Checked vitals and found the following.
Ambient 88°F
With A/C on high for 10 minutes
Clutch engages and compressor engages without unusual noise. (maybe too quite)
Low Side PSI 63
Hi Side PSI 210
Center Vent Temp 70°F
Turned AC Off and got the following
Hi Side PSI 130
Center Vent Temp 105°F with fan on high
The compressor is obviously doing some work.
Compressor Bad?
Orifice Bad?
Other?
Thanks for any help you can give me.
Thanks
Rick Hawkins
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Tom Greenleaf
Ultimate Carjunky
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Jul 8, 2010, 2:22 AM
Post #2 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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Rick,
Take vitals with a raised RPM and measure "ambient" temp as the air temp right in front of the grille not the day's temp on the news or elsewhere. High is high enough now and the low of 63 would yield only 70F outputs.
Is the fan for condenser working properly AND is it good an clear of dirt, bugs or whatevers?
Right now need the known incoming temp at what RPM observed. I'm leaning toward condenser not cooling well enough. Misting it with water will drop high pressure normally but if that alone puts all #s in perfect order than we can concentrate on that.
The other maybe is heater is blending in some heat making system work way too hard to blow cooler air.
Any history? Has any refrigerant been added? Those #s depending on other observations could also be an overcharge,
T
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rick59
Novice
Jul 8, 2010, 7:38 PM
Post #3 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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Thanks for the great reply. Went out this evening and found the following.
Engine at Idle
Ambient (right in front of condenser) 85 F
Lo 49
Hi 200
Vent 59
2000 RPM Constant
Ambient 80 F Temp was dropping rapidly with a storm near
Lo 59
Hi 300
Vent 50
Still 2000 RPM and sprayed water on condenser Ambent 78 Lo 59 Hi 275 Vent 54
Condenser fan running entire time and condenser does not look unusually dirty or buggy.
Saturday will check again and try to repeat with ambient more constant.
Also will find second thermometer as I was moving one between vent and ambient.
Turned off car and pressure equalized at 75PSI much lower than yesterday.
Yesterday noticed a leak at the high port but thought cap would seal it
Will see if static pressure goes down more.
Rick hawkins
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Tom Greenleaf
Ultimate Carjunky
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Jul 9, 2010, 2:55 PM
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Re: 2004 Liberty A/C Not Cold Enough
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Having puter problems but working on a real old wreck of one while it lasts and get other taken care of so if I,m not fast to reply I'm without puter.
OK - Static is just that - it would read the same with 2 oz or a pound too full. It's only relevant that it has enough pressure to show it should be able to try then about done with that.
Your pressure are all too high suggesting an overcharge. How did it behave when you misted down condenser with water? If that made every # perfect for the temp there's an airflow or heat exchange problem with the condenser.
If there's ever been a chance this thing has been overcharged I'd have it reclaimed and charge with specified amount EXACTLY as that's really the only way to know how much is in there. Gauges are a great diagnostic tool and when all is well you leave things alone. They can't tell but rather suggest where the problem area is likely. Both pressures too high is consistent with you output temps.
Side note: Neat thermos I use is the cheap automotive or household WIRED in/out thermometer. They are fast and you can just place the wire end in a duct and bring the main unit out and switch to see both temps without jumping thru hoops. I usually use two and place on on dash so I can see it. No joke - on sale they are like $5 - $10 bucks not on sale! I have the expensive ones and like those things better!
T
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Hammer Time
Ultimate Carjunky
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Jul 9, 2010, 3:11 PM
Post #5 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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I don't really think you have a problem at all. Assuming you had it set on high blower, if you can pull 50 degrees without the car moving in these temperatures, your not going to get any colder than that. Your pressures aren't that far off considering the outside temp. They will come down when it's not so hot out. Your getting all your going to get out of it.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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rick59
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Jul 10, 2010, 8:46 PM
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Re: 2004 Liberty A/C Not Cold Enough
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I'll admit that the temp did read 50 on one reading. Or maybe I misread or wrote down wrong that one reading. In fact there is a problem. Today, rolling down the highway I was getting a vent temperature in the 60's. I really appreciate the help I am getting here. Will get out and get some more numbers when the ambient temperature is stable.
At Idle
At 2000 RPM
At 2000 RPM while misting the condenser
Vent temperature while cruising with A/C full blast then with A/C off.
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Tom Greenleaf
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Jul 11, 2010, 6:29 AM
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Re: 2004 Liberty A/C Not Cold Enough
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IMO while misting condenser which is more effective than air could be should yeild maximum performance. Granted sitting still and revving engine is not real world performance so we take that into consideration.
I think the condenser MIGHT have some issues of dirt hidden perhaps between it and radiator if not seen. I can get all but a couple known fussy cars/vehicles into the 40s for vent temps without too much trouble without driving them. If it will hold 50F that's no terrible but think it can be better.
Take thermo with you for the road and watch the temps change at assorted speeds and conditions - full sun over hot pavement, and cool country roads will bounce performace up an down a bit.
Each day you have multiple factors playing on readings so they can be right for given conditions. Full sun, warm/hot engine, hot pavement, NOT LEVEL, and humidity some of the things that factor in.
We may have totally different conditions by climate. It can get hot and humid here (Eastern MA) but it's not the same as Southern heat and humidity or the dry high heat common to the SW of US.
If super humid the poor evaporator is so soaking wet with condensate (water) it doesn't exchange heat at it's best. I swear a little helps but tons doesn't.
Watch at second highest blower speed and vent temp will drop some as "residence" time for air going thru evap is a bit longer.
There's stuff published as to what is NORMAL but should always be a range as so many factors play into it,
T
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rick59
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Jul 23, 2010, 9:20 PM
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Re: 2004 Liberty A/C Not Cold Enough
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OK
Finally got off the dime and did a complete recharge on the system.
Followed all of the correct procedures, using a very good vacuum pump and high accuracy vacuum guage.
Actually weighed the refrigerant going in and the charge is about 10 grams short on an ~ 650 gram charge. (I don't remember what the exact number was but I charged per the number under the hood)
The system now has the correct charge.
To diagnose the system I connected several temperature probes to the system lines.
The temperature probes were taped down on metal lines and insulated.
Following the system from the compressor.
The discharge line travels about 12 to 18 inches and enters the condenser.
The DISCHARGE PRESSURE port is in this span a few inches from the condenser inlet.
The CONDENSER INLET TEMPERATURE was taken a couple of inches from the condenser inlet.
The CONDENSER OUTLET TEMPERATURE was taken a couple of inches from the condenser outlet.
From here the line travels about 8 inches to the orifice tube.
The SUCTION PRESSURE port is a few inches after the orifice tube.
The SUCTION TEMPERATURE was taken adjacent to the SUCTION PRESSURE port.
From here the line travels (uninsulated) about 2.5 feet to the evaporator inlet.
The line exits the evaporator and goes directly into the suction accumulator.
The line out of the suction accumulator travels about 12-18 inches to the compressor.
The EVAPORATOR OUTLET TEMPERATURE was taken just after the suction accumulator.
The following are the readings taken after the recharge.
-At Idle
-Fan on high
-System running for 10 minutes or more
-Several sets of readings taken and remained constant.
DISCHARGE PRESSURE 225 psi
CONDENSER INLET TEMPERATURE 171°F (About 32° Superheat)
CONDENSER OUTLET TEMPERATURE 120°F (Good heat rejection across condenser)
SUCTION PRESSURE 64 psi (This is too high right?)
SUCTION TEMPERATURE 71°F (Chart says says PSI should be 71 so maybe slight superheat here but maybe
temp and/or pressure gage slightly off)
EVAPORATOR OUTLET TEMPERATURE 102°F (This shows that the evaporator is absorbing heat)
CENTER VENT TEMPERATURE 76°F (My Plymouth van was making 62° immediately prior in the same ambient conditions.)
AMBIENT TEMP DIRECTLY IN FRONT OF THE CONDENSER 93°F
Later I went out and took temperatures in three places. - Directly after the evaporator (which is directly before the accumulator)
- Directly after the accumulator
- Directly before the compressor
This showed about a 10°F rise in this span which may indicate that the refrigerant is leaving the evaporator as a gas and picking up superheat along the way to the compressor.
The compressor is quiet and doesn’t seem to make excess noise.
Sure would like to know for sure what is wrong with the system so I can replace the right thing the first time.
For what it's worth,
This system is somewhat different from my Plymouth Van which is as follows.
The compressor outlet goes into the condenser
From the condenser the line goes into some kind of small vessel. Possibly a drier.
From there the line goes into a TX valve which is directly before the evaporator. The high pressure port is located in this line after the condenser and before the TX valve.
The line then goes directly to the compressor with no accumulator. The suction port is in this span between the evaporator and the compressor.
(This post was edited by rick59 on Jul 23, 2010, 9:57 PM)
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Tom Greenleaf
Ultimate Carjunky
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Jul 24, 2010, 4:49 AM
Post #9 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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I'm good and confused as to what the current knowns are. Proper performance is the objective and will vary based on an algorithm of data, pressures, temps and know accuracy!
****************
al·go·rithm (āl'gə-rĭ th 'əm) 
n. A step-by-step problem-solving procedure, especially an established, recursive computational procedure for solving a problem in a finite number of steps.
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Now with known weight of charge thought to be correct the #s don't add up but so many factors are involved you won't get exactly the same results based on several factors.
Now we seem to have sketchy belief of accuracy of gauges and I don't know how you recovered refrigerant and if refrigerant is pure. Air, even some from unpurged lines will throw the exact knowns off. Air doesn't condense to a liquid so doesn't evaporate. {yes it can but at some insane 1,000s of PSI so forget that}
*Don't compare one car to another. Too many variables color, glass exposure to sun and tons more. Even if parked at an angle it can change performance.
*When thermos or gauges are in doubt compare them with known accurate ones.
*Refrigerant must be known pure or all bets are off. When new it should less than .0010% !! It goes downhill from there and performance is compromised.
*Taping a temp probe to a line and even insulating it: Nice idea but can't trust that or see how well that was done. Infrared touchless thermometers just tell you instantly. Worth the $20 to get a small one or go for higher end stuff.
________________________
There may not have been a problem as Hammer mentioned back several posts. This thread is long and now hard for me to know right where this is right now. I suggest a new thread condensed with knowns and the observations when taken. About always, the output temp performance we seek will be when you are driving the vehicle in real world conditions not while sitting still working on it,
T
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Hammer Time
Ultimate Carjunky
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Jul 24, 2010, 5:30 AM
Post #10 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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OK, I just have one question for you.............
Are you an engineer by trade?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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rick59
Novice
Jul 24, 2010, 1:16 PM
Post #11 of 11
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Re: 2004 Liberty A/C Not Cold Enough
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Not Exactly, Have a 2 year associates degree in mechanical engineering but currently work as a lab technician.
Thanks for the help I have received here. I truly apreciate all who have taken the time to help.
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