A/C issue with 2005.5 a4

[jfiggins]

Just bought my first Audi, and the a/c sorta blows cold, but not really. Decided to pick up a set of gauges from Amazon to see exactly what was wrong. Here is what I found:

Car off on low pressure side - ~70psi
Car off pressure on high pressure side - 90psi

Car on no a/c low side - 100psi
Car on no a/c high side - 100psi

Car on with compressor running low side - 80psi
Car on with compressor running high side - 120psi

Any idea on what exactly is wrong? Condenser from the outside doesn't look clogged, and the fan is turning on and off when the AC is turned on and off, but I was reading that the low side should be around 30-40psi with the compressor on and 200 for the high side. Is that correct?



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[a4lownslow]

Low on Freon meaning you have a leak. Recharge see how long it lastd


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[jfiggins]

Low on Freon meaning you have a leak. Recharge see how long it lastd


Sent from my iPhone using Audizine (http://r.tapatalk.com/byo?rid=87676)I'm totally new to doing anything with a/c, what should I charge it to? It seems like when the car is running, the low pressure is too high? I've read many places that it should be around 40psi when running.

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[a4lownslow]

I'm totally new to doing anything with a/c, what should I charge it to? It seems like when the car is running, the low pressure is too high? I've read many places that it should be around 40psi when running.

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Your low pressure should be around 40. I’m not sure what your ambient temperature is but if you look up a pressure temp chart you can determine where high side should be. The easiest place to start would be to add Freon seeing if you can reach the correct high pressure side and get the compressor to cycle and bring down the low side


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[jfiggins]

Your low pressure should be around 40. I’m not sure what your ambient temperature is but if you look up a pressure temp chart you can determine where high side should be. The easiest place to start would be to add Freon seeing if you can reach the correct high pressure side and get the compressor to cycle and bring down the low side


Sent from my iPhone using Audizine (http://r.tapatalk.com/byo?rid=87676)What is considered "too high" for the low side? i.e. when should I stop adding freon in case it doesn't start cycling? Thanks for all your help!

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[wding2000]

This video explains how HVAC system works, and has Lo-Hi table.
https://www.youtube.com/watch?v=QKmbO3rAd3Q&feature=youtu.be

Lo and Hi pressures depend on ambient temp. Lo can be anywhere from 25 - 55 psi, Hi 80-200 or even 300. Your refrigerant may be low. but at least it allows compressor kick on. Your main issue is: Lo is too high and Hi not high enough, when AC on.