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manifold gauges both going in vacuum

slodub2 on Mon May 30, 2011 9:05 PM User is offline

Year: 1999
Make: vw
Model: jetta
Engine Size: 2.0
Refrigerant Type: r-134a
Ambient Temp: 80
Pressure Low: -15
Pressure High: -15
Country of Origin: United States

ok i dont know to much about a/c systems, but i replaced a compressor and charged the system while running on high with manifold gauges, (i did not have a vacuum pump to remove everything from the system) but i charged the system and when its off it shows pressure but when its running both high and low sides go the whole way into vacuum. Can some one point me in the right dirrection with this?

slodub2 on Mon May 30, 2011 10:33 PM User is offline

also i dont know much about a/c or the componates, but its frosting from the expansion valve on the high side down to the cylinder thing behind the front bumper where where it goes into the a/c condensor and has some kind of switch or something with wires on it. sorry i dont know much at all about a/c. im here to learn

mk378 on Mon May 30, 2011 11:17 PM User is offline

Where is the high side port? There is an obstruction between it and the compressor, thus the pressure drops into vacuum. Your condenser and/or receiver drier is probably stopped up with debris from the old blown compressor. Frost should not appear on the receiver drier (the cylinder part) or the other high side lines before the TXV.

slodub2 on Tue May 31, 2011 7:34 AM User is offline

both service ports are at the firewall right befor the expansion valve

slodub2 on Tue May 31, 2011 9:28 PM User is offline

also it sounds like the engine rpm drop really really low at idle when it is on. im just wondering if its the compressor? any thoughts?

mk378 on Tue May 31, 2011 10:06 PM User is offline

It's a variable compressor it's not supposed to pump below 20 psi in any case. Clearly the receiver drier and likely also the condenser are obstructed. At a minimum the receiver drier should always be replaced with any major service like a new compressor. It is also essential to remove air from the lines before charging. Replacing the entire system is not out of the question at this point.

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