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Strange A/C problem

 
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  #1 (permalink)  
Old 07 Jul 2014, 03:04 pm
Young Cruiser
 
Join Date: Apr 2014
Posts: 76
Default Strange A/C problem

I have a 2001 Limited Edition. Fun car.
I live in Mesa Arizona. As many say around here, Mesa is only 10 miles beyond hell. I personally don't feel that way but it does get sizzling around here. Lately we have been above 105 during the day and around 80+ at night. Needless to say, air conditioning is vital around these parts.
Well, last week, I didn't feel my A/C was quite doing it's job. 105 and it was blowing out at 60 to 65 degrees so I got out my gauges and "topped it off" just a little. I started with about 50 pounds on the low side and brought it up to about 55. It didn't really make much difference though. Yesterday it just stopped blowing very cold. It was around 105 again but it was blowing out the vents at 80+ so I removed just a little freon and got it down to 50 pounds again on the low side. The air is blowing out around 70 now but still not very good.
The freon I used to "top it off" was 134A that Walmart had on sale. 3 12oz cans for just a little over 20 bucks. I'm wondering if that freon sucks.
Is there any difference between manufacturers of freon? Is one brand of freon better than others and if so, why?
So should I just evacuate the old freon and start over? All the pressures look good and all the equipment is functioning normally. Any ideas??????
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Old 07 Jul 2014, 03:11 pm
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Join Date: Mar 2012
Location: darien il
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Default Re: Strange A/C problem

that walmart 134a is the ONLY thing i buy from walmart and it always works great for me. i'm talking the stuff with no dye/oil/etc.. just the straight cheap 8.97 a can R134a.

i just added a can of the carquest stuff with dye to my mustang after the walmart stuff leaked out, and i can tell you that i immediately noticed my air is warmer with that in there.

i like the walmart stuff though. you'll never hear me say that again. i hate that store.
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Old 08 Jul 2014, 01:45 pm
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Join Date: Apr 2014
Posts: 76
Default Re: Strange A/C problem

I have about 50 lbs. of pressure on the low side and only about 70 or 80 on the high side. What should I have on the high side?
Did I somehow clogg up the orafice?
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Old 08 Jul 2014, 04:45 pm
Senior Cruiser
 
Join Date: Jan 2014
Location: SW PA
Posts: 1,354
Default Re: Strange A/C problem

Did you loose all your freon charge then try to recharge it?
__________________
Addicted to Mopar You can tell how old I am..
65 Dodge Coronet 6 cyl 2dr Post
66 Ply Satellite with 273 engine swap to 69 340 4spd
70 340 4spd Dart Swinger "Those were the days my friend"
73 Charger SE
Had a few Vetts on the way 69, 85
Several Neons some flips
01 Sebring flip
Cruiser's 01, 220K Gone to a new home
Cruiser 03 133K Gone to a new home
Cruiser 06 110K Project Gone to new Home
Cruiser 05 Ltd 120,809 bought with broken belt Oct2015
May 16 Resurrected to once again roam the streets.

20 Miles South Of Pittsburgh
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Old 08 Jul 2014, 05:38 pm
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Location: darien il
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Default Re: Strange A/C problem

Quote:
Originally Posted by 1AZPT View Post
What should I have on the high side?


i let my friend deal with real AC issues, so i have no clue about the oriface tube. i have him vacuum/fill it. if the compressor cycles like it's low I add more until its cold. if the car starts to idle rough or it gets warmer, i bleed some back out. if it's still warm i bring it back to him to pick his brain. that's as much as I know about AC. usually gets me by.

below is everything i could find about AC on alldata

from alldata about charging:

Refrigerant Charge Capacity
The R-134a refrigerant system charge capacity for this vehicle is 0.709 kilograms (1.56 pounds/25 ounces) .

Partial Charge Method

WARNING: REVIEW THE WARNINGS AND CAUTIONS BEFORE PERFORMING THE FOLLOWING OPERATION.

The partial charge method is used to add a partial charge to a refrigerant system that is low on refrigerant. To perform this procedure the evaporator inlet and outlet tube temperatures are measured. The temperature difference is measured with a temperature meter with one or two clamp-on thermocouple probes. The difference between the evaporator inlet and outlet tube temperatures will determine the amount of refrigerant needed.

Before adding a partial refrigerant charge, check for refrigerant system leaks. Refer to Refrigerant System Leaks for the proper procedures. If a leak is found, make the necessary repairs before attempting a full or partial refrigerant charge.

Attach a manifold gauge set to the refrigerant system service ports.
Attach the two clamp-on thermocouple probes to the inlet and outlet tubes of the evaporator coil.

If a single thermocouple probe is used, attach the probe to the liquid line just before the connector block for the evaporator. The probe must make contact with the bottom surface of the liquid line.
If dual thermocouple probes are used, attach probe 1 to the liquid line, and probe 2 to the suction me. Attach both probes to the lines just before the connector block for the evaporator. The probes must make contact with the bottom surfaces of the liquid line and the suction line.

Open all of the windows or doors of the passenger compartment.
Set the heater-A/C controls as follows: Airflow control in Recirculation, Mode control in Panel, Temperature control to the full Cool position, Blower control in the highest speed position in the A/C compressor ON direction.
Start the engine and hold the engine idle speed at 1,000 rpm . Allow the engine to warm up to normal operating temperature.
The compressor clutch may cycle, depending upon ambient temperature, humidity, and the refrigerant system charge level. If the compressor clutch cycles, unplug the wire harness connector from the low pressure clutch cycling switch on the accumulator. Install a jumper wire between the two cavities of the switch wire harness connector.
Hold the engine idle speed at 1,000 rpm .
Allow three to five minutes for the refrigerant system to stabilize, then record the temperatures of the liquid line and the suction line.

If a single probe is used, record the temperature of the liquid line. Then remove the probe from the liquid line and attach it to the suction line just before the connector block for the evaporator. The probe must make contact with the bottom surface of the suction line. Allow the thermocouple and meter time to stabilize, then record the temperature of the suction line. Subtract the liquid line temperature reading from the suction line temperature reading.
If dual probes are used, record the temperatures of both the liquid line and the suction line. Then subtract the liquid line temperature reading from the suction line temperature reading.

If the measured temperature differential is higher than 22 C to 26 C (40 F to 47 F) , add 0.4 kilograms (14 ounces) of refrigerant.
Allow three to five minutes for the refrigerant system to stabilize, then take a second set of thermocouple measurements. Record the temperature difference to determine if an additional charge is required.

Fig.31 Compressor Discharge Pressure


Record the compressor discharge pressure. If the reading is higher than the pressure shown in the Compressor Discharge Pressure chart, the system could be overcharged. If the reading is equal to, or lower, than the pressure shown in the chart, continue with this procedure.
EXAMPLE: The ambient temperature is 21 C (70 F) . The evaporator inlet tube temperature is 12 C (54 F) and the evaporator outlet tube temperature is 10 C (50 F) . Subtract the inlet tube temperature from the outlet tube temperature. The difference is 2 C (-4 F) . With a -2 C (-4 F) temperature differential at 21 C (70 F) ambient temperature, the system is fully charged.
Add enough refrigerant to bring the refrigerant system up to a full charge.
Remove the jumper wire from the low pressure clutch cycling switch wire harness connector and reconnect the connector to the switch.

---------

for testing the high pressure switch it lists this:

Before performing diagnosis of the high pressure cut out switch, verify that the refrigerant system has the correct refrigerant charge. Refer to Refrigerant System Charge Test for the proper procedures.

Disconnect and isolate the battery negative cable.
Disconnect the engine wire harness connector from the high pressure cut out switch on the back cover of the compressor.
Check for continuity between the two terminals of the high pressure cut out switch. There should be continuity. If OK, test and repair the A/C switch sense circuit as required. If not OK, replace the faulty switch.

----------

for testing the low pressure switch it has this:

Before performing diagnosis of the low pressure clutch cycling switch, be certain that the switch is properly installed on the accumulator fitting. If the switch is too loose it may not open the Schrader-type valve in the accumulator fitting, which will prevent the switch from correctly monitoring the refrigerant system pressure.

Also verify that the refrigerant system has the correct refrigerant charge. Refer to Refrigerant System Charge Test for the proper procedures.

Disconnect and isolate the battery negative cable.
Disconnect the headlamp and dash wire harness connector from the low pressure clutch cycling switch on the accumulator fitting.
Install a jumper wire between the two cavities of the headlamp and dash wire harness connector for the low pressure clutch cycling switch.
Connect a manifold gauge set to the refrigerant system service ports.
Connect the battery negative cable.
Place the heater-A/C mode control switch knob in any A/C position and start the engine.
Check for continuity between the two terminals of the low pressure clutch cycling switch. There should be continuity with a suction pressure reading of 262 kPa (38 psi) or above, and no continuity with a suction pressure reading of 141 kPa (20.5 psi) or below. If OK, test and repair the A/C switch sense circuit as required. If not OK, replace the faulty switch.
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Last edited by rob342; 08 Jul 2014 at 05:59 pm.
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Old 08 Jul 2014, 07:37 pm
randyincctx's Avatar
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Join Date: Jun 2013
Location: Corpus Christi,Tx.
Posts: 3,485
Lightbulb Re: Strange A/C problem

If your PT has it's original drier(13+ years old?),it may need to be replaced due to air or moisture contamination.
You can do a simple smell test.....With the engine off you can depress the low side service valve slightly,just to get a smell(you may need to use charging hose,so you can control the refrigerant flow).
All you want is a small vapor sample,don't blow the charge or try to freeze your nostrils,use common sense.(and NO huffing freon!)
Typically,a healthy system should have almost no,to very little odor.
A burn't oil or acidic smell may indicate the presence of air and moisture in the system and should receive further attention.(probably drier replacement).
A neutral to slightly sweet smell is also normal.
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Old 09 Jul 2014, 12:00 pm
Young Cruiser
 
Join Date: Apr 2014
Posts: 76
Default Re: Strange A/C problem

I have the proper charge in there.
I talked to a couple of A/C guys and it's beginning to look like the compressor is weak on the high side. I thought the compressor had just one piston. Apparently they have two or more. The low side has it's own piston/s and the high side has it's own piston/s. If that is the case, then I could understand that one side could be weak.
Any thoughts?????

The A/C is working, just not very well. If I'm idle and the outside temps are 100, the coldest it blows is about 75+ degrees. If I drive about 10 miles on the freeway, it will get down to about 63 degrees but in town with stop lights, it won't go below about 72.
I'd hate to spend the money on a compressor if that isn't the problem. I hate just throwing parts at something.
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Old 09 Jul 2014, 10:08 pm
Senior Cruiser
 
Join Date: Jan 2014
Location: SW PA
Posts: 1,354
Default Re: Strange A/C problem

You may want to clean the condenser with special foam cleaner then rince the outside of the condenser with water, don't blast it with hi pressure,
Don't damage or bend the thin aluminum cooling fins andYou may want to check to see if the coolin fins are still attached to the coils
Surly you don't have bugs in that heat blocking the cooling fins.

As the out side temperature goes up, system pressure goes up too and you need more air going through the condenser located in front of the radiator to cool the freeon for the compressor to liquify the gass for the system to work properly. Since your cooling ok at highway speed there is nothing wrong with your system, you just need more air going through the condensor. Try locating another half size fan to blow through the front of the condensor. and make sure it is pushing air the correct direction or you could end up with the AC working not as well as it is now.

You could tap off your cooling fan wiring hi side to run an auxilary fan relay to control the power for the extra fan wired and fused from the battery. Trouble is there is not much room to put one.
__________________
Addicted to Mopar You can tell how old I am..
65 Dodge Coronet 6 cyl 2dr Post
66 Ply Satellite with 273 engine swap to 69 340 4spd
70 340 4spd Dart Swinger "Those were the days my friend"
73 Charger SE
Had a few Vetts on the way 69, 85
Several Neons some flips
01 Sebring flip
Cruiser's 01, 220K Gone to a new home
Cruiser 03 133K Gone to a new home
Cruiser 06 110K Project Gone to new Home
Cruiser 05 Ltd 120,809 bought with broken belt Oct2015
May 16 Resurrected to once again roam the streets.

20 Miles South Of Pittsburgh

Last edited by JoeX; 09 Jul 2014 at 10:13 pm.
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