Got a 97 Camaro over the winter. AC needed charged so a friend did it. We got it to a point it will cool to at 45 degrees out the vents on MAX when driving down road but after about a mile the comp. will kick out. At a standstill the pressures are 45/ 260 at 78 degrees ambient temps. What causes these systems to cycle when driving? As an fyi it will not cycle at a stop at idle and blows around 57 degree air on MAX.

 

It could be a few things, Most of the time ii is the low pressure switch turnning off the compressor because the low side has gotten too low. Most of the time it is caused by not enough Freon. It can also be caused by the high side pressure switch reading too high of a pressure. The could mean too much Freon or a part way plugged orfice tube. These system are not designed to cycle the system is protecting itself from damage unless it is just a loose wire.

 

can you advise where the orafice tube is at?

 

near the dryer but you're cracking open the system to get to it.

 

yep, no problem. if we start over I will check that tube. Here is a question. I notice when running the AC the cooling fans run on a pretty low setting. Most cars run the fans pretty high with AC on. could airflow across teh condenser be the issue and I ahve a fan issue causing this? THe wierd thing is it wont cycle idling and does on highway, which makes em think airflow should be ok, but maybe gettign too high of high side pressure as RPM is higher.

 

Step one should be figuring out if it is the high or low pressure that is turnning off the compressor. If it is the high side then yes the fans could cause it.

 

I am betting it is a high side issue and the system is over charged. Unlike R12, You have to charge the system based on the Ambient temperature of the area you are working in.

Take a look at this chart. http://www.ackits.com/aacf/ptchart.cfm

On the right, you can find out the temperature of your garage and charge the system accordingly.