AC stops working after 10-15 minutes - Volvo, S70 SE, year 2000

There are 2 common causes of the A/C working fine for a while - typically 30 minutes - then cuts out and doesn't work until the car has cooled off.

One is a superheat switch that turns the compressor off when it gets too hot. This switch is on the backside of the compressor. You need to join the 2 wires going into it together. The best way is to follow both wires to a connection about 6" (15 cm) away, disconnect the superheat switch wires and connect the 2 other wires together. (The connectors will just plug into each other.) Do not remove the superheat switch, as the refrigerant will come blasting out. Note that the design idea of the superheat switch was to save the compressor from overheating, its setting is too low, causing the compressor to turn off when there's really no problem.

The other cause is that the gap in the compressor clutch being too large, and the magnetic force is not strong enough to engage the clutch. (Removing the superheat switch from the circuit as described above will help this problem, as it will increase the voltage available to the clutch a small amount.) Others have used the wire going to the clutch to engage a relay that is fed power directly from the battery.

I had the very same problem this week with my 98 V70. Took it to the shop and they sucked out the freon and found it significantly low. They recharged with the right amount of freon and added a leak detector dye. The system has been working perfectly since then.

Bill

Bob135 wrote:

Hi, I've got the other problem with my AC. My clutch doesn't engage. I'll try the fix this weekend and post an update

Thanks

Eric