Mechanics

AIR NOT COLD ENOUGH

2004 Jeep Liberty

Air Conditioning problem
2004 Jeep Liberty 6 cyl Four Wheel Drive Automatic 104000 miles

Air conditioning not blowing cold enough inside.

Checked vitals and found the following.

Ambient 88 °F

With A/C on high for 10 minutes
Clutch engages and compressor turns 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

The compressor is obviously doing some work.
Compressor Bad?
Orifice Bad?
Other?

Thanks for any help you can give me.

Thanks
Rick Hawkins
Avatar
Rick59
July 7, 2010.



Hi
By readings system is low on charge. Has system be opened? Any repairs? Low 35-40 high 250-350
Let me know
Thanks for donate

Docfixit
Jul 8, 2010.
Low on charge?

Wouldn't the low pressure be below the normal of 35-40 psi not way over at 63 psi if the refrigerant was low?

Tiny
Rick59
Jul 8, 2010.
That's why I asked about system beinging open and repairs. Low side is high due to moisture or faulty blend door allow heat to enter evaporator. High side to low either low charge or compressor fault. So has system been opened or repaired?

Docfixit
Jul 9, 2010.
System has not been opened or repaired during the two plus years I have owned the vehicle. Air conditioning worked great until the recent past.

Any easy way to check the blend door function?

Took a reading of the vent temp with the air off the other day and it was 105F even though the ambient was 88.

Tiny
Rick59
Jul 10, 2010.
Please add some 134A I believe you will see low side go down and high up

Docfixit
Jul 10, 2010.
I had originally added refrigerant, a whole can, and the suction pressure was still high. So then, thinking I had overcharged I let some out, now who knows how much refrigerant is in there.

So since the last poste I 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.
1. Directly after the evaporator (which is directly before the accumulator)
2. Directly after the accumulator
3. 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.

Tiny
Rick59
Jul 23, 2010.
I show a fixed Orfice tube not a TVX. Two possibilities for elevated Suction blend door not shutting allowing heater core to warm evap. so acess through glove box see diagram


http://www.2carpros.com/forum/automotive_pictures/198357_Graphic_526.jpg

see if motor operates from warm to cold. other but have not seen in CCOT is Orfice tube damaged not droping pressure entering EVAP. any TEMP differential befoe and after Orfice?

Docfixit
Jul 26, 2010.