I had a 2002 Nissan and they are very sensitive as overcharging it by less than a Lb made it into a heater. It blew steaming hot air.
You can't really just let out some and hope for the best as modern r-134a systems are very sensitive as you have found out. Shops make mistakes and it happens so if you took it to have it serviced and they did this, take it back and ask that they fix it. Shops take a lot of time with come-backs as they do not want to see them again or have bad complaints posted on the web about them as complaints tend to carry a lot of weight when potential customers see them.
If you did it yourself, make sure you get the right specs for both cycles and make sure the right amount of oil is in it if you have never changed it yet. You may want to completely flush and fill it if you have never done that as old r-134a can stay in the system and make it less efficient. Also old or insufficient amounts of oil can ruin a compressor. Have a shop do it that has the proper equipment and expect to pay at least $50.00 or more. It is worht it as it is hard to get r-134a to give you more than a 20 degree difference in temperature from ambient, so every degree counts.
Sunday, August 26th, 2012 AT 12:14 AM