AIRBAGS WONT DUMP

Hi,
I have 2013 Volvo and I'm trying to fix the airbag problem. The airbags are not dumping from the dump switch, however it shows on the instrument cluster that the airbags are dumping and it also makes a little hissing noise when I turn the switch ON. I manually gave the air supply to the airbag dump line on the suspension valve and it is dumping the bags just fine. I followed the dump airline that goes from levelling valve to the solenoid valves and changed the "ASAP SOL VALVE" but still the problem remains the same. I checked the main air supply on the solenoids it is good because the air horn and the diff. locks are working just fine. Help me if anybody knows about this please.