I have a 2000 s2k. 108k. I recently started to have this problem, My a/c lately has been turning off and on when im on the highway. But when im sitting or cruising around in first to 3rd gear it will remain on. As soon as i go into 4th and above a/c will blow hot and turn back on after 10 to 15 min. I live in az so its hot and its a drag to not have a/c out here. Any ideas?

 

It is normal for the a/c system to cycle; about every 30 seconds or so. It may cycle off during acceleration and other pre-programed situations in the compressor built in ecu/relay.

If the cycling is occurring faster, say every 5 seconds or so it could indicate several things. Most likely you are low on coolant. You may have a small leak. Cycling increases as the coolant drops but if the pressure is too low, the compressor clutch will not engage. On the flip side, there is also a high pressure switch. (You have a low and high pressure sides.) You fill on the low pressure side. If the pressure increases too rapidly, somewhere north of 350-400 psi, the compressor will cycle off. When the pressure drops quickly, it will go on again only to be shut down again. That is probably not your case as you did not mention servicing it. That is why you do not want to over pressurize (overfill) with coolant.

Your solution depends on your budget. The least expensive way to go (you have some cooling left so the system is not empty) is to get some coolant with a gauge to measure how much to add. Any auto parts store/ Wal Mart has it. However, sooner or later, you will need to find the leak. You can do that a number of ways, but the bohemian way is to look for oil residue and get a soapy spray bottle and see if you can find something bubbling. Next step up is to get a light for leak checking. After that is take it to shop.

If the system is empty, you will have air and moisture in the system. A vacuum purge should be used to get that out, the longer its on the better. Consider replacing the dryer too. If you don't and water or air remain in the system, it will not be as efficient. Good luck!

 

Its super cold when im just idling. I can be driving at 50 mph. And ill put in neutral or simply just hit the clutch and my a/c will turn back on. Also i feel when the car kicks the a/c on when im on the highway. Ill be cruising with the a/c on and all of a sudden i feel the engine change and my a/c throws hot air. And then evemtually the engine will change again and throw cold air. Is that still a leak? Or is it my compressor going out?