a/c compressor not engaging....

last year my a/c worked off and on. so far now its not working at all. compressor isnt kicking on. i bought a bottle of the EZchill refrigerant to recharge the system. I took the relay out and added 12+ to the pin to kick on the compressor. even with the compressor running the gauges are in the blue range which is the normal operating range. with the compressor running, the air is cold but when i stick the relay back in the compressor wont kick back on. i tested the relay and its fine. thoughts?

also the compressor is rattling.

verify the control signal to the relay; in other words, is the relay being told to turn on? from your description, it sounds like an electronic control issue.

Possible pressure sensor problem...

"also the compressor is rattling"

Agree on the control issue but in addition to that problem the system is low on oil,( the compressor rattling). You'll need to repair the leak and recharge with proper refrigerant and oil charge. If it still rattles you'll need to replace the compressor and drier.

I also noticed this. I have the electronic dual climate control and if it displays the correct outside temp then the a/c works. If it display the wrong outside temp then the a/c won't kick on. Like right now the real temp is 75. The dual climate shows 28 and the compressor isn't kicking on. Would that prevent the compressor from kicking on?

Well, if you are not reading Celsius, from the control head, that could be the problem........I think outside temp has to be a min of 45F to allow the compressor on.....

With the digital climate control the the controller thinks it knows what you want. If the temp is not reading correctly the climate control won't work correctly. It sounds like your outside temp sensor is going wonky and probably needs replaced.

The outside air temperature sensor is behind the grill in front of condenser. Went bad on my 98. Cheap and easy to replace.

yeap that worked. $12 part and a/c works good now. thanks guys