The air conditioning works only intermittently. The fan comes on and off without apparent cause. Is this a common problem with a known cause? Is there a sensor that can be replaced?

It could be a dirty cabin temp sensor, except that I dont know where they are in the 70s.

Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)

It does go on and off as your temp. settings in the cabin control a thermostat. When the temp goes down to the thermostat setting (Temp you set in the cabin...68, 70, 72, etc.) then the A/C goes off until the temp rises and then it comes on again to cool down to that point. The fan will keep blowing during this time. If you have the vent wheel to the left of the center vents (closest to the instrument dash) turned all the way up, when the A/C clicks off, you'll get outside air inter your cabin. If it is extra hot outside, this air may feel hot and make you feel as if your A/C is not cooling. Try turning this wheel all the way down and off in that case. If all this doesn't do the trick and your A/C is cycling off and on rapidly then you are probably low on coolant and need a boost, or worst case senario is that your evaporator is leaking which could be a major repair and $$.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon

Thanx for the input. I am not sure if this is my problem. The FAN, not the air conditioner cycles on and off with no apparent cause. Is the fan controlled by an internal thermostat that is failing/failed or is there some other electical gremlin I need to look for?

Could be the fan relay or even motor with a short. Is there any rhyme or reason to the off and on?
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon

That is the confusing aspect. There is no apparent rhyme or reason to the intermittent action. I am going to check the cabis temp sensor to see if it is dirty as suggested by Klaus. Will somebody tell me where I find the sensors? It would be lucky if it were so simple.