I noticed, suddenly the air flow is worm. I guessed its a refrigerant leak and turn to refill center, those technicians pointed that the radiator fan doesn't work when I turn the AC on.

I checked the fan by disconnecting ECT sensor and fan runs smoothly.

So Volvo owners, does your fan turn on when the AC is on?

Also might this be a thermo sensor issue?

 

There are two fans, at least that's the case for my 2003. One runs when the engine reaches a certain temp. The other runs when the AC is on. The first has two speeds, the second does not. Not sure if that helps you.
















I would start by confirmed that your AC compressor turns on when the ac is turned on. If it does not, you either are low on refrigerant or you have an electrical problem (the former is way more likely). if the compressor comes on then that is good news. I'm pretty sure that the second fan should come on shortly after the compressor turns on...verify that as well.

 

Thanks for the reply, in 1999 model, there's only one fan. For both engine heat and for the AC. I figured out the AC compressor's clutch doesn't work automatically, However if I manually supply current, it clutched. I refilled the refrigerant and now clutching works and the fan works. The problem solved.

However one thing I learned and I explained to AC mechanic also. Compressor doesn't start, unless enough gas pressure inside the AC system, So the first thing would be to refill the refrigerant using a proper gauge. This will solve most of the issues.

ps:
I'm not exactly sure, is it same with the other car brands, because the mechanic always work with Japanese cars and he denied my explanation.

 

Pretty sure that is standard operating principles. I think your AC guy is a hack.

 

Every car you'd ever see uses low pressure cutout on the evaporator pressure, to turn the compressor off. This is for cold control. Cars require cold control or else the evaporator will freeze. If the Freon leaks out, then of course they won't run, because this pressure would be low.




Condenser fan control is a little more varied.