So my AC has been slowly going down hill. The clutch kicks on and off every 3 seconds or so. I figure it must be low on coolant. I get a new can with a gauge and the gauge at first reads into the full. As soon as the compressor kicks on it drops to almost zero and remains there. I keep the trigger pulled on the can. The can gets cooler, but the compressor kicks off every 3 seconds still. It keeps cycling and the gauge jumps up and down, but the can is still very heavy, and nothing is going in. the high pressure line is cold, but the air inside the truck is still warm. Any ideas?

 

I wonder if the blend door might be be to blame? You might want to either buy an engine stethoscope (bout $10.00 at the parts store, and much safer I think) or a screwdriver and place it on the compressor housing. Listen to make sure that you can hear the cylinder pumping. If it isn't, more than likely your gonna be looking at a new compressor.... You could possibly try adding a can of AC Oil and see if that works. (Slim chance though.)

 

Use a paper clip to make a jumper for the low side pressure switch. It's on the accumulator by the firewall. This will keep the compressor running and will drain the r134a can. Only do it with the one can for now . And wear gloves and eye protection!!!

 

It sounds like the orifice tube(expansion valve) is clogged. to fix it though you would need to open up the system which will deplete all of the freon in your system. If the orifice tube gets clogged then it will prevent the coolant from passing through the system efficiently enough to allow the system to be effective. It does also sound like you are low on freon based on the compressor cycling every few seconds.

 

That could work, but I wouldn't recommend doing it unless he wants to take it to the shop to get the lines vacced to a negative pressure again, or if he has a way to do it at home.

 

best thing to do is find the leak and fix it. most of the time the evap canister inside the dash is the blame. go get a dye kit from parts store and a new can of freon. and ditto on the paper clip trick it will fool the compressor until you get the freon in.

 

Hey I forgot to mention how to vacuum the lines out again. If you pull the schraeder valve out of the high side port and run the engine for about ten minutes you will create the vacuum necessary to refill the system. My father taught me that trick about 20 years ago and I just used it on a vehicle a few weeks ago so I know it works on newer systems. If you can't remove the valve just depress the schraeder so that the air can escape. It will take a few more minutes but does the job.