My electric fan comes on when it wants to, usually on low speed, but sometimes on high speed. The temperature gauge indicates that the cooling system is perfect. Even in 100 deg F heat today, the cooling system remained at the temperature it has maintained from new.

However, my A/C shuts down in temperatures over 95 deg F. I am trying to determine if it is caused by a defective superheat switch in the compressor or from inadequate cooling. (It is not low on refrigerant.) I am used to cars where the electric fan runs whenever the A/C is on, but since this car has 2 computers involved with the A/C, this fan behavior may be correct.

I know this is an old posting but....... my fan on my 99 V70 XC runs all the time. Now the AC is on, but I am surprised that the fan comes on as soon as the engine is started, or shortly htere after, (even when the engine is cold). My 740 fan usually takes a while and after you shut off the engine the fan stops; on the V70 the fan may continue to run for several minutes. Is this normal?

Today it was a hundred degrees. With my 98 S70 parked in the driveway
(and the AC on) the electric fan took about 90 seconds before it came on.
I rarely even hear the electric fan on my car and was wondering if it
was even working (which is why I just parked it in the heat to see how
long it would take).

Also, like your carm my 98 will no longer blow cold air for more then
about 5 minutes when the temp is over 90 degrees. I suspect low
refrigerent in my case, though.

The cooling fan should always be on with the AC on, compressor running when the high side pressure goes up.
If that's not happening, there's a problem. If the fan is running but the compressor won't run at higher temps, one should check the systems high side pressure (done via dealers Vadis PC on '99 on up). AC compressor will shut off if pressure gets too high (high freon temp, no fan will do that) or if the compressor temp gets too high (some model yr compressors, not all).

One other question:
I have had the A/C cut out in 98 deg weather while driving at 70 MPH. I would assume that a 70 MPH airflow across the condensor would cool the refrigerant even if the fan wasn't working? So I probably have a problem with the superheat switch?

Oh, BTW, when the A/C cuts out, there is still power at the connector that plugs into the A/C clutch wire, so the ECU thinks the compressor should be running. Under these conditions, the fan may or may not be running. This leads me to think that the ECU MAY be programmed to turn the fan on only under certain conditions even if the A/C is running.

I am trying to solve the exact problem with my 96 850. Today I replaced the oriface tube and found a lot of gunk on the screen of the old one. Tonight the cut-out still occurred. I also notice that the compressor cuts off when the vent air temp reaches 38-39 degrees. I am beginning to beleive that I need a new compressor/clutch. If there is voltage on the wire and the compressor clutch isn't engaging then there must be a cut-out in the clutch coil.
Let us know what you find.
--
Tom 69-1800S, 72-1800ES, 96-850T

The voltage is on the wire coming from the harness. Most likely it dodges into the compressor and through the superheat switch after that point, but before getting to the clutch.

Tomorrow, I am going to get under the car, unbolt the compressor and have a really good look to see if there is a superheat switch on this car or not. If there is, I am going to install a long jumper wire that I can cut later to restore the superheat switch if the problem proves to be in the fan controller.

The other day, it was 105 deg F, and the A/C cut out. The fan was running when I stopped the car, but it MAY have been running due to coolant temperature. After the car sat for 20 minutes, the fan and A/C worked. They both worked for about 10 miles (usually in hot weather, the A/C is only good for about 3 miles) and were working when I shut off the car to go into a store for 5 minutes. When I came out, neither the fan not the A/C worked. I drove home, and jumpered the fan to run on high. After 6 minutes, (99 degrees out) no A/C. I got the garden hose and watered the condensor for 2 minutes, then waited 3 minutes. Still no A/C. Then I turned the hose on the compressor for 2 minutes. After 2 more minutes, the A/C came on, but no fan.

So, I am sure that the superheat switch is disengaging the compressor, but still not sure whether it is due to a defective switch or intermittent fan operation.
That's why I am going to install a removeable jumper wire. I will disconnect the battery for 30 minutes to clear the computer fault codes that may have been caused by my troubleshooting and then get it onto a VADIS machine to see if there is a problem with the fan.