Does anyone have a 2008 VT880 wiring diagram?

Low pressure due to a leak and not enough refrigerant, or no refrigerant, will cause the a/c clutch to not engage. It is designed this way so the compressor is not burned up if/when the refrigerant charge is low. You may have a bad clutch. You can disconnect the wiring to the compressor and apply 12v to see if the clutch engages. Or, if you have not already checked, see if you have 12v going into the connector that attaches to the compressor connector.

 

Still did not say if you checked the pressure in the system? Usually 2 switches, a low pressure and a high pressure. Start at the compressor and follow the lines. Most times switches are outside of the firewall. If not, you will have to go behind the dash where the heater core and evaporator are. If the switch has 2 wires 1 is signal and 1 is ground. Low pressure switch should have continuity between the 2 terminals. Meaning that the pressure in the system is adequate and allows current to flow through the switch. 3 wire would be trial and error w/o a diagram. One 5v reference, 1 signal and 1 ground. Then there is likely an a/c control module.

 

this is because they are european design diagrams all volvos are same, your ac module is what connects to ac compressor and directly responsible for turning on or off. you pressure sensor on firewall line, also there is a freeze switch in the evaporator assy all these are inputs.

 

Psi is relative to temp ac off not running full charge roughly ambient temp for example at 70f should be around 72psi when ac running should be high side up to 300 psi and can comes on to bring down psi low side between 20 to 40 psi low side u can look up psi chart on Google for r134a. U can test freeze switch but it’s a pain cuz u need to put in ice and measure resistance or u can replace it I think it’s around $50. Or so sold separate behind blower.

 

Might be module most like freeze switch or I think it’s called evaporator temp have u checked if there is power coming to your compressor with ac running maybe possible compressor clutch went to ####.