Hi i have a 2003 honda accord 2.4L automatic with 286,441 miles. I am going to atempt to charge my ac system. Upon preparation i have learned that if the refrigerant is too low the compressor will cycle off. But if i pull the low pressure cycling switch plug and attatch a jumper wire across the teminals of the electrical connector (on the harness side), this will keep the compressor on. Well i did that , had the ac on , fan on high , recycling button on but compressor clutch did not activate. Both the condenser fan and radiator fan came on and they both went off when i pressed the ac button while using the jumper wire and also while the plug was properly connected to the ac pressure switch. But compressor clutch never kicked in. I hoping your reply will save me the time and money that will surely be wasted if I charge the ac and then learn the compressor clutch is bad. I look forward to your advice. Thank you very much, knwood.
It should not be necessary to jumper the low-pressure switch. When you pull vacuum, or if the pressure is so low the compressor won't turn on, pressure from inside the can will push refrigerant into your AC system until the compressor can run. It helps to keep the can warm. I use a coffee can with hot tap water (about 120 degrees) on a hot plate set to just maintain that water temperature. You don't want the water to get too hot or the can may burst.
I just did this exact thing a few days ago on my old Jeep which has an evaporator leak. Pressure in the system was too low for the compressor to engage but I was able to charge in enough just from the can so it would turn on. (I really do have to replace the evaporator but the entire dashboard has to be pulled out. Maybe next spring.)
The ideal/right way to recharge your AC is to evacuate the system and charge in the correct amount by weight. What you can frequently get away with if the system isn't empty is to carefully charging in a little at a time and stopping when you have decent outlet temperatures. ("Close enough for government work.") Of course if you have a serious leak that needs to be repaired or the refrigerant will just leak out again in short order.
Use a manifold gauge set to monitor system pressures and always wear eye protection when working with refrigerant.
