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A/C Problems

Steven.Ciaburri on Mon August 13, 2012 9:12 PM User is offline

Year: 2002
Make: Chevy
Model: Suburban
Engine Size: 5.3
Refrigerant Type: R-134A
Ambient Temp: 107
Pressure Low: 45
Pressure High: 280
Country of Origin: United States

Last year I went to get my A/C recharged and I had a guy who apparently was a good sales man, and sold me on some freon called Freeze-12. I was in a hurry so I let the guy do it.

It seemed to work pretty good all year long, come this summer the A/C performance was suffering pretty bad. So I went to him and had him service again because I had suspected a leak (which I had and he fixed). Again the A/C was working great and pretty cold. 3 days later half way to lake havau ( 110F weather) the system froze over. We turned A/C off and let it thaw. Once it thawed we tried it again.. by the time we got to havasu I had some chattering from the compressor.

We drove it for about a month like this, and it repeatedly froze, i knew the compressor was dying so I just let it go. This weekend, the tensioner basically ripped off its mount on a day trip, so I replaced it on the side of the road, and it was basically rocking like crazy due to the compressor but it lasted the rest of the day.


Fast forward to now.
Sunday I replaced the compressor, the accumulator, orifice tube, and condenser as it was kind of beat up. I had it charged up today, and despite the shop telling me they got it to 42F (which they claim is factory spec, maybe someone can confirm please?). I have not been able to get it that low.

At Idle, I am measuring 68F. In town driving I am seeing 60F, and highway I am seeing 50F. This is at 105F ambient. They claimed to measure at 107F ambient.

They gave me the following numbers:

High Side: 280psi
Low Side: 45psi
Ambient Temp: 107F
Vent Temp 42F

The rear AC in my measurement was about 7-9F higher than the front.

Before I go yell at someone, what do you guys think? I let it idle in my driveway when I read the 68F and the compressor basically ran non-stop. The fan clutch is a severe duty one that I replaced a month ago and is still working properly

GM Tech on Mon August 13, 2012 10:26 PM User is offline

They were probably on low blower speed recirc-- while you were on high blower outside air...big difference

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Dougflas on Mon August 13, 2012 10:31 PM User is offline

You're dropping 55*. You should be happy with that. That system is not a freezer; it is an air conditioner. You're also dehumidifying.

Steven.Ciaburri on Mon August 13, 2012 10:54 PM User is offline

GM Tech,
I was not on outside air, I as mid blower recirculate.

Prior to the freeze-12, the AC operated much better on 134a as it is now.

Leggie on Mon August 13, 2012 11:46 PM User is offline

Replacing the compressor without a flush is like playing in the mud with a snow white shirt. It will quickly get dirty from whatever was left and can fail anytime.

Compare the air out the vent against the tube going back to compressor. If the tube is much cooler than the air, you may have blend door issues causing air to go through heater core.
If that's not it....

Freeze 12 contains HCFC, a chlorine containing refrigerant. PAG is not supposed to be used with CFC or HCFC. Now you may have more issues due to ruined oil.
If I were you, I would have the system completely flushed, re-replace the drier accumulator and orifice tube.

Drain the compressor. Move it around as if you're washing the inside of it. Drain again. Finally, refill with correct amount of clean oil. This step is normally not necessary but , because you allowed old nasty oil to circulate into your new compressor you contaminated it.

Evacuate, check leak, fix as needed. Finally charge with 134a.

Steven.Ciaburri on Tue August 14, 2012 12:15 AM User is offline

That is a good suggestion, that tube is colder than the air coming out of the vents. I will check that tomorrow.
I was planning on having it flushed as you mentioned this week.

mk378 on Tue August 14, 2012 9:19 AM User is offline

I agree with Leggie, Freeze-12 is likely to cause major damage in a factory 134a system. Same with HC refrigerants ("Freeze-12" was a real HFC / HCFC product approved to replace R-12 in old cars. But there are also a zillion mysterious gases on the market with names that end in -12 which are typically HC).

Overcooling and freeze-up is controlled by the pressure switch on the accumulator. If you experience freeze-up again, unplug the switch and the compressor should stop. If it doesn't, there's an electrical problem. If it does, it is likely the switch is bad.

Edited: Tue August 14, 2012 at 9:40 AM by mk378

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