Question about 1999 Volkswagen Passat

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AC not cooling for 97 Passat TDI

System evacuated.Originally charged through low pressure side. Read in manual later that all procedures are supposed to be performed on high side. Evacuated system again, and charged system thru high side.
Before starting, 70 lbs high and low. Start engine, put on AC and both sides go down to about 20-25 lbs and clutch disengages. Pressure rises a little and clutch engages. Noticed high side pipe gets cold and low side pipe no change. No cooling present.
Already replaced compressor with no change.
Any suggestions or ideas?

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First recharging throug the high side is extremely dangerous and is discouraged by most HVAC mechanics.
High side pressure should read approx. 5x the low side. Low side pressure should read in the 40-45psi range unless otherwise specified by the manufacturer. Guess here is the system is overcharged is you're getting 70psi on the low side. Overcharging will damage the compressor and will underperform. Below is a link to a great source of information on AC.
http://www.cyberbright.com/autobin/air_conditioning.htm
Best of luck with your problem.
Greg

Posted on Aug 01, 2009

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A/c should be charged on the low side while engine is running. Make sure high side valve is turned off. Low side reading should be around 32-35 psi at idle high side should not go above 250. I hope this helps,good luck

Posted on Aug 01, 2009

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