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Low side screen AND high side filter?

barnabas1969 on Wed September 21, 2011 11:20 AM User is offline

Year: 2005
Make: Saturn
Model: VUE
Engine Size: 2.2L
Refrigerant Type: 134a
Country of Origin: United States

Hi there. I'm new to the forum, but an old-hand at DIY automotive stuff. My compressor finally failed. I've been expecting it for a while because the pressures looked like the TXV is plugged up and the evaporator was freezing up. If I added enough refrigerant to get the low side pressure high enough so that the evaporator would not freeze, the high side pressure was WAY too high.

So, now that it has finally failed, I'm looking at replacing the compressor, TXV, drier, and condenser (I've read that they're almost impossible to flush and the new one is only $75). I'm planning to flush the system, but an in-line filter really seems like a good idea (and is recommended by GM).

I know some folks think a low-side screen is useless because they don't believe that debris could make it past the TXV or the evaporator. However, I've read that when a compressor has a catastrophic failure, the high side pressure can blow the debris backward through the compressor and into the low side tubing and even into the evaporator.

So... as an added insurance after doing a flush, I'm thinking that it might be a good idea to install a high-side liquid line filter AND a low-side screen on the suction side of the compressor. But, I'm wondering if this might restrict the flow of refrigerant and oil too much (because there would be TWO filters in the refrigerant path).

Anyone have any experience with installing BOTH a liquid line filter AND a low-side screen?

Thanks in advance.

Brian - Melbourne, FL USA

mk378 on Wed September 21, 2011 11:30 AM User is offline

The TXV can't cause the evaporator to freeze up. Freeze-up in automotive systems is always a control problem. Your car has a variable compressor that is supposed to internally slow or stop pumping before the low side pressure gets low enough (
Edited: Wed September 21, 2011 at 11:35 AM by mk378

barnabas1969 on Wed September 21, 2011 12:33 PM User is offline

Well, if it was contaminated with air, it must have been there from the factory because the system was never opened before the freezing problem started. I've owned the car since it was new. It worked fine for the first 150,000 miles. It has 191,000 miles on it now. The compressor is definitely shot now and needs to be replaced, so there's no point arguing about the original cause of the problem.

My question was about installing BOTH a liquid line filter AND a low-side screen in the suction port of the manifold. Any experience with doing so?

Brian - Melbourne, FL USA

GM Tech on Wed September 21, 2011 12:56 PM User is offline

Low side screens are installed in suction port on all service V-5 I use them everywhere with no issues.....

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......

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