Dear fellow "Brickboarders":

My A/C system works only intermittently (as outlined below). What are your thoughts / advice if my system charge is accurate, and there are no leaks? Symptoms outlined below:


My thoughts are that it must have something to do with the "ambient pressure", and the system's interpretation of that pressure. This is because of a) my system is properly charged, b) there is no leak, c) it cools properly and constantly when the outside temperature is below 75 degrees----approximately. Once the outside temperature climbs beyond that, I begin to notice the problem; and, the problem appears to escalate as the outside temperature increases. I also notice that if I turn off the a/c switch and leave it off for some time, then turn it back on, it will begin to cool again, but only for a short time until the problem repeats itself.

From what I've been able to gather, the problem would be with either 1) the pressostat / low pressure switch, 2) the high-pressure switch (Volvo refers to it as a MAPP sensor?), or 3) the compressor itself. NOTE: I've already checked the pressostat, so that leaves 2 or 3. Which is it? Or, is it something else altogether?

FYI: I've been told by one Volvo shop that it could well be the compressor, as the compressors that were installed in my particular model / year were notorious for this issue. the shop said that this compressor would exhibit this problem because once the clutch cycled "off", it wouldn't re-engage / turn back on.

Lastly, if it IS the compressor, do I HAVE to drain the coolant and remove the radiator----as the service manual says, or is there an easier way?


Thanks so much,

Sweating in Virginia