well its just one more thing, yesterday started using ac, compressor seems to run non stop, then will overheat and shut down for long periods of time. when i can get it to work again works fine but will not circulate on and off. get overheated and shut down. dose anyone know what it is? how to fix, if not fixable how much volvo will carge to fix. thanks, kelly

greetings,
i had this exact problem, it got fixed when i replaced the compressor. FCP groton has about $325, plus fliter. do it yourself not too bad a job.
i replaced the cycling switch etc etc. to no avail tried everything spent lots of $$$.i wish i would have replaced the compr. first,
mine would work for 10-20 minutes then shut off for 10 minutes got worse over time, has overheat device and timer i believe when temp of refrigerant (or compressor?) overheats it shuts down the compressor till everything cools, maybe this type of compr wears more quickly because it cycles? not sure, typical Volvo money pit,
good luck
frankd, south florida

Wouldn't a low level of refrigerant cause it to overheat and
shut down? Since slow leaks are so common as to be considered
normal I would have a look at that. My 98 is low on refrigerant
and will run about 5 minutes then blows hot air for 15 then
will run again for 5 minutes. My plan is to have it recharged
(soon) for this summer.

The local dealer sometimes runs a special where they remove the
existing refrigerant and add back the exact correct amount along
with a dye pack (for detecting future leaks). Cost was around $100.

Look for the pressure switch on the upper A/C line close to the firewall. That switch lets the compressor run if there's enough refrigerant (pressure). Unplug it and see if the compressor stops. I'm guessing the pressure switch is defective or maybe there's a short somewhere.

thanks will give it a try. kelly