The A/C in my 96 850 works fine (has had the evap & compressor previously replaced). BUT, I have a question on how often the A/C compressor should cycle on and off.

When I'm stopped in traffic or at a traffic light, the compressor runs continuously in 80+ degree weather. However, once I start moving and RPM's increase, the cycle times decrease. When on a highway in 80+ weather, the A/C is on 6 seconds, then off a couple seconds, then back on 6 seconds.

I should say that by the time I'm on the highway, my car is cold and the climate control has the fan very low. But is 6 second cycling too fast? What is the norm cycling time range for highway driving?

Thanks!

With your key phrase being that your a/c "works fine," I would say quite loudly to leave it alone. If it is effectively cooling your car, then it seems unlikely that it is low on refrigerant!
If you're too curious, buy a gauge at Autozone $10-20 and check it out.
Point #2: too much refrig. is as bad (worse?) than not enough. People very often overcharge their systems . . . my 2 cents.
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Two 1995 854 GLT's (w/ manual transmissions)

cycling every 5-6 sec is not normal and indicates low refrigerant.

You probably have a leak in the system. Most like a hose, fitting or the recharge valve. I hope the repair shop added leak detector when they replaced the evap. That makes finding the leak easy.

The valve at the charging port is a common spot for leaks. Get a valve removing tool at the autoparts store (about $3.00) and tighten the valve as needed.
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'88 240, '92 745, '98 v70 -John, Tampa Bay

The a/c typically cycles for a couple of reasons, the most common is low refrigerant levels. It will also cycle if you have it set on a low fan speed to keep the evap from icing over. The reason it cycles when you are low on gas is that the low side pressures get to low and the cycling switch opens. At idle the compressor is not spinning fast enough to get the pressures low enough with the quantity of gas you have in the system. When you come off idle and the compressor spins faster the low side pressure drops, the cycling switch opens, and the compressor clutch disengages. Now if you had the correct amount of gas in the system it would not be able to get the pressures low enough to cause it to cycle. So with it on high fan speed, rev it up and see if it cycles, if it does you are a little low on refrigerant and need to either top up the system or do a complete evacuate and recharge of the system. You can try tightening the schraeder valve in the low side fill port or just replace the darn thing. I own a shop and have to guarantee my work so I do not dick around with tightening stuff, I stuff a new one in it an be done with the damn thing. Seeing as how you obviously have a leak, it would be nice if you could put some UV tracer dye in the system while you are servicing it.

Mark

I agree with the previous posts. Too much r134a is a bad thing, trust me!

I would get a recharge kit and measure the pressure, leave the gauge on while the car runs for a bit to stabilize the system. I think you will find you're a tad low on r134a.

In my mind, the AC should be so cold that I have to turn it off, not leave it running full blast all the time. You can get a thermometer to measure the air temp from the vents, too.

My AC was too cold yesterday, even in the 99 degree DC heat, I had to turn it down. That's properly working AC!

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