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 Post subject: Air Conditioner issue
PostPosted: Thu Aug 12, 2021 4:59 pm 
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Location: central ct.
Hi
2005 Liberty crd, around 140k, wifes daily driver. While I have done a decent amount of work on this vehicle in the 13 or 14 years we have had it, I have never been in the air conditioning system.

Symptoms: just recently it has turned in to a sauna at low speed in traffic driving, with the occasional glimpse of cool. On the highway the performance is closer to normal, but not as good as it use to be. Since Im not in it every day it is hard to gauge performance.

I have listened to it with the hood open and can verify both the engine and electric fans are working. I can hear the compressor engage for maybe 10 seconds at a time, and when parked if i rev the engine to about 2000 rpm the ac will work intermittently.

My first thought was that it was low on 134 , so i bought a can that has a digital gauge on it. So when I went to plug it in to the system I didnt turn the can valve on so i could see what the pressure was, surprised the hell out of me. Engine off my first pass had the pressure at 150/160 , and when the engine was running it may drop to 70 or 80 psi. I started to wonder if i was plugged in to the right fitting ! Please find the enclosed photo the fitting nearest my thumb is where i plugged the gauge in, is the the right location to do a low side pressure test ? Keep in mind I have never messed with the system and until recently gave her good performance.

If what i saw is correct im assuming it isnt normal.....anythoughts on what might be the issues? is it safe to run the system as is or will she wreck something ?

ps still trying to figure out how to post my pic ....the port im using is passenger side front next to washer fill

thanks, steve

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bought a 05 liberty limited crd with 47 k, 10/08 got a trans and steering on warranty
11/13, 89k, timingbelt ,waterpump tstat,alternator, cooling hoses,gde echo
5/16, 112k, cylinderhead, rockers, charge hoses, tstat, waterpump all hoses, euro converter
jba lift , 245/70/17. wifes ride want to keep it going as long as possible...


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 Post subject: Re: Air Conditioner issue
PostPosted: Thu Aug 12, 2021 7:12 pm 
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The can will only connect to the right port - the high and low side are of different sizes to prevent people from blowing themselves up.

When the compressor is off, the two sides will eventually equalize in pressure. That number is for all intents and purposes meaningless.

When the system is on, the indicator that it's generally working is a massive difference between the low side and high side pressures.

Unfortunately, modern cars are filled by weight and not by pressure, so those parts store kits really aren't super useful. The pressure guidance they include is based on worst case scenarios; most modern cars will run higher pressure than the kit indicates is safe. Further, AC pressures will be affected by outside temperature, so "system pressure" really isn't a meaningful number. You can use generic R134a charts to get you a sense of where you should be, but they are not conclusive:

Image


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 Post subject: Re: Air Conditioner issue
PostPosted: Thu Aug 12, 2021 8:49 pm 
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Location: central ct.
thesameguy wrote:
The can will only connect to the right port - the high and low side are of different sizes to prevent people from blowing themselves up.

When the compressor is off, the two sides will eventually equalize in pressure. That number is for all intents and purposes meaningless.

When the system is on, the indicator that it's generally working is a massive difference between the low side and high side pressures.

Unfortunately, modern cars are filled by weight and not by pressure, so those parts store kits really aren't super useful. The pressure guidance they include is based on worst case scenarios; most modern cars will run higher pressure than the kit indicates is safe. Further, AC pressures will be affected by outside temperature, so "system pressure" really isn't a meaningful number. You can use generic R134a charts to get you a sense of where you should be, but they are not conclusive:

Image




Thankyou for the reply.
So if I saw the elevated pressure on the low side after the vehicle hadnt been started in 3 hours, is it possible that the pressure i saw represented both sides of the system ? At this stage im wondering the higher pressures im seeing is a result of the compressor not being able operate for a long enough period of time to make the system fully pressurize ? I cant help but wonder if i put some refrigerant in and see what happens? Never added any before and by the looks of things the system will have to be opened up sooner than later.

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bought a 05 liberty limited crd with 47 k, 10/08 got a trans and steering on warranty
11/13, 89k, timingbelt ,waterpump tstat,alternator, cooling hoses,gde echo
5/16, 112k, cylinderhead, rockers, charge hoses, tstat, waterpump all hoses, euro converter
jba lift , 245/70/17. wifes ride want to keep it going as long as possible...


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 Post subject: Re: Air Conditioner issue
PostPosted: Thu Aug 12, 2021 9:21 pm 
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Location: Central GA
Sounds like you are low in freon. If you have gauges, add some 134a until the low side pressure is holding steady between 30-40 psig if ambient temperature is in the 65-70 deg. range. Higher ambient temperatures will affect charge temperatures as shown in the chart riggler posted.
Another thing to check is the intake screen over the HVAC system when using the recirculating setting. Check it for being clogged with dust and lint. See first picture below.
Next, if you do the 11 blade GM fan conversion, the AC will cool much better especially at lower engine speeds. See second picture below.

Image

Image

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05 Jeep Liberty CRD Limited :JEEPIN:
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 Post subject: Re: Air Conditioner issue
PostPosted: Thu Aug 12, 2021 11:31 pm 
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Joined: Wed Nov 05, 2008 5:22 pm
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Location: central ct.
Thanks for the info ! Where do iI find that screen exactly?
I guess i will put some in tomorrow and see what happens, a little at a time

_________________
bought a 05 liberty limited crd with 47 k, 10/08 got a trans and steering on warranty
11/13, 89k, timingbelt ,waterpump tstat,alternator, cooling hoses,gde echo
5/16, 112k, cylinderhead, rockers, charge hoses, tstat, waterpump all hoses, euro converter
jba lift , 245/70/17. wifes ride want to keep it going as long as possible...


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 Post subject: Re: Air Conditioner issue
PostPosted: Fri Aug 13, 2021 12:27 am 
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riggler wrote:
Thanks for the info ! Where do iI find that screen exactly?
I guess i will put some in tomorrow and see what happens, a little at a time

Watch this YouTube video, it shows you how to get to it and clean it.
https://www.youtube.com/watch?v=Y2HZ4qSx1uM

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited :JEEPIN:
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Sasquatch BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 bld.fan/NAPAHDClutch
IronrockArms/wwdieselMount


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 Post subject: Re: Air Conditioner issue
PostPosted: Fri Aug 13, 2021 11:16 am 
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[quote="riggler"]So if I saw the elevated pressure on the low side after the vehicle hadnt been started in 3 hours, is it possible that the pressure i saw represented both sides of the system ?[/quote

Yes, the pressure will equalize after a period of time. This number is essentially meaningless. The only things that matter are the pressures when the system is running.

It is unreliable and potentially dangerous to fill only reading the low side port which is how all these parts store "kits" work. You really need to see both sides to get anywhere, and even that's not as good as the proper method of filling by weight. Don't get me wrong - filling by pressure is basically what you're limited to as DIY, and it's how I do it, but, seriously, you can't do anything useful with those parts store kits.

If you want this to work and be right, my advice is to have the system vacuumed out and refilled and replace the receiver/drier at the same time. Some of this you can do at home with about $150-$200 in tools. Most places it seems the going rate for a vacuum/recharge is about $250-$300 ... which IMO is short money for another 10 years of AC. Still, it's one of those things that first time you do it the parts cost puts you in the negative, but the second time you break even. :) Of course, you're always going to be paying someone $50-$100 to recover the existing refrigerant... *that* tool is a grand. :D


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 Post subject: Re: Air Conditioner issue
PostPosted: Sun Aug 15, 2021 10:56 am 
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As WWdiesel suggests, your issue does sound like low refrigerant. However, if the pressures are deemed to be correct, the symptoms could also be caused by a failing low pressure switch on the accumulator. If the switch has completely failed, the a/c compressor will not cycle at all, but if the switch is on it's way out it can demonstrate your symptoms. Section 24, page 43 in the FSM is the start of the pressure switch sections. Note, the low pressure switch can actually be changed without evacuating the system as there is a schrader valve on the accumulator.

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2006 KJ CRD, 2006 KJ 3.7L 6spd., 2015 Ram 2500 6.7L 6spd., 2013 Subaru BRZ 6spd., 1969 Dodge Charger R/T 4spd. (Yes it's a Hemi).


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 Post subject: Re: Air Conditioner issue
PostPosted: Sun Aug 15, 2021 1:24 pm 
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There is a High side pressure switch that can also affect AC clutch & fan operation. It can also be changed without discharging the system.
AC Pressure Transducer -- 05072138AA
Operation, Testing, and Diagnosing is covered in the 2005 Factory Service Manual in section 24, page 22 to wit:

FACTORY SERVICE MANUAL wrote:
24 - 22 CONTROLS ---------------------------------------------------------------------------------------------------------------KJ
A/C HEATER CONTROL (Continued)


A/C HIGH PRESSURE SWITCH DESCRIPTION
The A/C high pressure switch controls both A/C compressor clutch engagement/disengagement, and electric cooling fan operation when equipped with the 2.8L diesel engine. The A/C high pressure switch is mounted on a fitting located on the A/C discharge line near the A/C compressor. The A/C high pressure switch turns off the A/C compressor if the refrigerant system pressure exceeds 3100 - 3375 kPa (450 - 490 psi). The fitting for the A/C high pressure switch on the A/C discharge line is equipped with an O-ring seal and contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant system.

OPERATION
The A/C high pressure switch is connected in series electrically with the A/C low pressure switch between ground and the engine control module (ECM). The contacts in the A/C high pressure switch open and close causing the ECM to turn the A/C compressor clutch on and off. This prevents A/C compressor operation when the discharge line pressure approaches high levels, and also reduces electrical surging from A/C clutch engagement.
The A/C high pressure switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the A/C discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the A/C discharge line pressure drops to 1600 kPa (235 psi).
The A/C high pressure switch contacts open when the A/C discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The A/C high pressure switch contacts close when the A/C discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi). The A/C high pressure switch is factory-calibrated and cannot be adjusted or repaired. If the A/C high pressure switch is faulty or damaged, it must be replaced.

DIAGNOSIS AND TESTING A/C HIGH PRESSURE SWITCH
Before performing diagnosis of the A/C high pressure switch, verify that the refrigerant system has the correct refrigerant charge (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE) For circuit descriptions and diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
(1) Disconnect and isolate the negative battery cable.
(2) Disconnect the wire harness connector from the A/C high pressure switch.
(3) Check for continuity between both terminals of the A/C high pressure switch. There should be continuity. If there is not continuity, replace the faulty A/C high pressure switch. If there is continuity, test the A/C high pressure switch sense circuit (Refer to 8 - ELECTRICAL/WIRING DIAGRAM INFORMATION - DIAGNOSIS AND TESTING). Repair as required.

REMOVAL
NOTE: It is not necessary to discharge the refrigerant system to replace the A/C high pressure switch.
(1) Disconnect and isolate the negative battery cable.
(2) Disconnect the wire harness connector from the A/C high pressure switch (Fig. 20).
(3) Remove the A/C high pressure switch from the A/C discharge line and remove and discard the O-ring seal.

INSTALLATION
NOTE: Use only the specified O-ring as it is made of special material for R-134a. Use only refrigerant oil of the type required for the A/C compressor.
(1) Lubricate a new rubber O-ring seal with clean refrigerant oil and install it on the A/C high pressure switch fitting. (2) Install the A/C high pressure switch onto the A/C discharge line. Hand-tightened the switch securely. (3) Connect the wire harness connector to the A/C high pressure switch. (4) Reconnect the negative battery cable.
(2) Install the A/C high pressure switch onto the A/C discharge line. Hand-tightened the switch securely.
(3) Connect the wire harness connector to the A/C high pressure switch.
(4) Reconnect the negative battery cable.


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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited :JEEPIN:
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Sasquatch BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 bld.fan/NAPAHDClutch
IronrockArms/wwdieselMount


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 Post subject: Re: Air Conditioner issue
PostPosted: Sun Aug 15, 2021 5:26 pm 
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I missed that you have a 2005 model.

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2006 KJ CRD, 2006 KJ 3.7L 6spd., 2015 Ram 2500 6.7L 6spd., 2013 Subaru BRZ 6spd., 1969 Dodge Charger R/T 4spd. (Yes it's a Hemi).


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