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Old 05-26-2010, 03:57 PM   #1
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Default Intermittent A/C

So I put a new (reman) A/C compressor in last week and now I am having intermittent A/C. I flushed the system, replaced the accumulator, orifice tube, lubed the compressor, pumped it down (held pressure for 40+ minutes) and filled it with R134A to the correct pressure. At first startup I had ice cold air....32* when driving. Sunday I was driving and it was blowing 77*...wtf? So I checked the pressure just to make I didn't have a leak that didn't show up when I pumped it down. Pressure read 55 psi (running at max) which was right going by the chart (it was in the 90* range outside). Compressor was spinning (not just the clutch) the cold side of the lines had condensate on them and they felt cold, but my A/C sure wasn't blowing cold. Last night I checked it again, about 80* outside and my pressure was 38 psi. Seemed a bit low according to the chart so I added a little more R134A with system safe leak fix and dye and gave it a few minutes to run. Pressure was now 45 psi and the A/C was 54* at idle and 38* cruising...right where I should be. So this morning I head to work and the a/c feels normal (was running on low whole time). I stopped to get gas and decided to look under the hood. My cold side lines had a layer of ice on them....not frost, but ice...like 1/16" thick! Today at lunch I decided to go for a drive....felt like the A/C was at like 70* degrees again! WTF? I don't have my gauges with me so I couldn't check it (will check when I get home from work), but the cold side lines had condensate on them and felt cold, compressor was running, everything seemed to run as normal, but the A/C coming out sure wasn't as cold as it should be. Checking around I found that my vacuum line running from the vacuum "blimp" in front of the passenger tire had broken off, but as far as I understand that will only effect my ability to switch where the air comes out of (which takes forever to switch, so I know that is a problem and will fix it today). Evap is getting cleaned out today as well, but my air velocity seems acceptable, so I don't think that is it either Vehicle has ECC and the display does not blink or anything like that. Any ideas on what to check next?
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Old 05-26-2010, 09:11 PM   #2
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Update: On the way home, the A/C never got below 72.5*. This included a 25 minute span at 70 mph on the e-way. Ambient (based on the ECC) was 94*. Pulled in the driveway (left A/C on the whole car ride at max) and checked the pressure. 52 psi.

I fixed my vacuum line to allow me to switch which vent the air comes out of. I ended up having to put a new line from the 'Y' fitting in the harness all the way to the vacuum module under the bumper. The original line was REALLY brittle the entire length. Anyway, it'* fixed now, and the vents change when I tell them to!

I also cleaned the Evap out. Looked fairly clean and not much came out, but it did seem to help my passenger side airflow.

Got it all back together and ran the A/C on max while I was finishing up. Sitting in the driveway idling (Ambient at 88*) the A/C got down to 62*. Went for a drive. After 10 minutes at 60 mph the lowest the A/C got was 54*. When I got home and checked the pressure again, it was still 52 psi.

Don't know if any of that helps diagnose, but it'* all I got.....why can't it be consistent?!?!??!

Last edited by SNK SKNR; 05-26-2010 at 09:13 PM.
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Old 05-27-2010, 07:54 AM   #3
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Being low side pressure, that sounds high. The best thing to do is have one of us with FSM'* get the pressure/temp chart posted so that you can know if 52 is too high for the temp/humidity outside.
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Old 05-27-2010, 08:26 AM   #4
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Quote:
Originally Posted by BillBoost37 View Post
Being low side pressure, that sounds high. The best thing to do is have one of us with FSM'* get the pressure/temp chart posted so that you can know if 52 is too high for the temp/humidity outside.
The pressure could be a tad high, I was going by the chart on my gauge which says I should be in the 45-55 range at 90* ambient (which it was, really humid too, like 90%+). I know I put in enough R134A that it could be a little overfull, but I expected the pressure to reflect that. When I originally filled it, I put in exactly what the sticker under the hood says, 2 lbs. Then I added more when the pressure only showed 32 psi. Anyone have those FSM'* that could post the chart or give me some idea of where it should be? The other thing I am pondering is that it could it be my air-mix actuator. I spent some time digging around the forum and found some people who looked like they had the same condition and it was the actuator (though they mention the ECC blinking or showing ---. Mine does not do that). So, I pulled the glovebox liner and watched the arm move. It moves what seems to be all the way to both sides when it should, but at 2 locations along the travel it seems to "hiccup", almost like there is a tooth missing (or the gear is split). Also, on the drive in today, my a/c was blowing at 75* at max cool when outside it was 67*. So I ran the temp to max heat and it climbed to 130*. Then, I turned it all the way back down to max cold. My A/C was now blowing at 45*.
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Old 05-27-2010, 09:08 AM   #5
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  1. Important: Record the relative humidity and ambient temperature conditions at the time of the test.
    <LI type=1>Park the vehicle inside or in the shade. The ambient temperature must be at least 16 C (60 F). <LI type=1>Open the windows in order to ventilate the vehicle. <LI type=1>Vent the engine exhaust. <LI type=1>Open the hood and install the J 39183-C <LI type=1>Record the ambient temperature where the vehicle is parked. <LI type=1>Record the relative humidity. Use a psychrometer or consult the local weather bureau. <LI type=1>Close the doors and windows. <LI type=1>Set the A/C control assembly to MAX mode with the blower speed set to high, the temperature to full cold. Ensure that the vent button LED is not illuminated. <LI type=1>Open the A/C air outlet deflectors. <LI type=1>Place a thermometer in the left center A/C outlet. <LI type=1>Place the transaxle in PARK. Start the engine. Let the engine idle. <LI type=1>Run the A/C system until the outlet air reaches a stabilized temperature (about 3 minutes). <LI type=1>Record the outlet air temperature and the high side and low side pressures. <LI type=1>Turn the engine off and compare the readings with the data in the A/C Performance Table. Normally operating A/C systems should not exceed levels shown. <LI type=1>If the readings exceed the table limits. Refer to High Side vs. Low Side Pressure Table and Gray Area Diagnosis and Service in Cooling Insufficient.
  2. If you were sent here from a DTC diagnostic table be sure to clear the DTC upon completion.
<A href="http://gsi.xw.gm.com/si/showDoc.do?laborOpCode=&docSyskey=297105&cellId=48 723&pubObjSyskey=297105&from=sm&pubCellSyskey=4872 3#tab1-297105">A/C Performance Table

Temperature
Humidity
Low Side Service Port Pressure in PSIG
High Side Service Port Pressure in PSIG
A/C Discharge Temperature
16C (60F)
Less than 40
28-34
110-130
6-8C (42-46F)
High
32-38
160-190
7-8C (44-46F)
21C (70F)
Less than 40
30-34
190-210
3-6C (38-43F)
High
34-40
200-220
7-9C (44-48F)
27C (80F)
Less than 40
28-36
160-180
4-7C (40-45F)
High
38-36
170-190
6-9C (43-48F)
32C (90F)
Less than 40
34-40
180-200
6-9C (43-48F)
High
34-40
190-210
7-10C (44-50F)
38C (100F)
Less than 40
38-46
200-220
9-12C (48-54F)
High
42-50
210-250
13-17C (56-62F)
43C (110F)
Less than 40
48-60
280-340
16-20C (60-68F)
High
54-64
340-360
21-23C (70-74F)
49C (120F)
Less than 40
56-64
320-360
17-22C (62-72F)

Darn thing didn't paste very well.
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Old 05-27-2010, 10:20 AM   #6
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Going by that, it says I am a little overfull. I'm not surprised (I added an extra can that I didn't need to when I first had this issue), but the more reading I do about the airmix actuator, the more I am thinking that is the problem. If the door controlled by the actuator isn't closing all the way when I start the car on full cold (because of a bad actuator), I will be pumping in some heat with my A/C. I guess one way to test it would be to to pull the glovebox liner, pop the rod off of the actuator and push the door all the way to one side and see if the temp drops to where it should be.
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