Do the easy inexpensive stuff first. h: What is the pressure on your low pressure side of the A/C? My wife's nissan had a very similar problem with the compressor switching on and off very often and never blowing very cool. Turns out it had too much refrigerant and built up pressure too quickly. Most A/C compressors have built in mechanisms to switch off if the pressure is too high to avoid damage to the compresor. So the switched on and then switched right back off since the pressure built up so fast. The result was exactly what you describe (you'll be lucky if it's that easy). The mechanic drained some refrigirant from the system and voila, worked like a charm, blows like the arctic breeze now . Get an A/C refrigirant pressure guage from the auto parts store and check it. Get the specs for you car from a hayes manual or the internet possibly. If it's a little higher it shouldn't be a problem but my wife's nissan was at about 60psi on the low pressure when it should have been around 32psi. Alot of people get those cans of refrigirant and pump their system up way too high thinking that more is better. Anyway, It's worth a try. It's not a bad idea to keep a pressure gauge around anyway to check your A/C to see if it's too high or low. It could very well be from a low refrigirant level too.