I've got a 98 pickup with a 318. I was having trouble with my AC so I took it into a shop to have it fixed. They filled the freon and checked for leaks and everything seemed fine. After driving for 15 minutes the air stops blowing cold and just blows air. After several minutes the air will kick back on blowing cold. After this, its 5 minutes on 5 minutes off etc.. I took it back to the shop and they told me that the freon was fine and there were no leaks. The guy told me that after warming up, the clutch disengages because it moves slightly forward. When the clutch cools down it reengages. He gave me the option of letting him try to rig it, or buying a new compressor/clutch. Needless to say, I didn't let him rig it. Any ideas on how to fix this?

Sounds lik the clutch needs to be replaced to me. The switch inside the vehicle could also be messed up. I had that happen to my Grand Caravan.

Josh Hi... My 97 did the same thing. I had to have a new clutch put in. Also it was cheaper for me to buy the whole compressor/clutch unit together. It is easy to replace yourself. Donald

I went on a trip this weekend with my truck and found that the A/C works great in cooler weather and at speeds around 70 mph. Is there a sensor or something that might need replaced or perhaps the engine compartment needs more air circulation? I hate to replace the whole compressor/Clutch only to find the problem is still there.

I had a similar problem with my truck. there is a preasure switch that controls the clutch, to keep the preasue in the system at a certan leval. if I remember correctly, it is located on top of the can shaped thing on the firewall. when I took mmine in, they found that the connection for the preasure switch had just come loose, and didn't need replacing. not sure if this is your problem, but it might be worth having the switch checked.

I checked the connection, and it seemed fine, I'll monkey around with it a little, I'm replacing the plenum gasket this weekend so I'll probably replace the ac compressor/clutch while it's apart.
Thanks for the info!