Air conditioner blows hot air......any advice? Volvo S80 sedan

 

Year, engine?

Compressor coming on?

Any experience or knowledge of how an automotive electrical/ac system works to be able to understand things to check?

 

2011 Volvo s80......husband changed the relay switch, compressor not kicking on.

 

Only engine option in the US that year is the FOMOCO 6 cyl with or without turbo. Either way the AC compressor clutch on that engine has a "dampening ring". I have replaced several of those clutches because that ring comes loose and prevents the clutch from closing. If that ring is loose you can loosen the compressor, take the inner part of the clutch off, remove and discard the loose dampener ring, reassemble and the clutch should work fine (might make a noisier click when it engages) Or purchase a new $300 or so clutch and install that. However a more common problem with the compressor on the 6cyl cars only - is the compressor displacement valve stops working properly. That valve controls the displacement of the compressor by changing the angle of the swash plate. They tend to get stuck in the - "sorry not making any cold air today mode". Easy to replace, recover freon, replace valve, evacuate and recharge system.

Have you checked to make sure there is 12 volts getting to the compressor clutch? (by unplugging the compressor and testing the voltage at the connector) If there is power and the clutch is not turning - I would inspect the compressor clutch. If the clutch is actually spinning the compressor and the big pipe on the compressor does not get cold (careful the small pipe can get very hot) the next step would be to check ac pressures, and scan the car for any self diagnostic codes. With a good scanner you can verify all sorts of parameters - for instance if the ac evap temp sensor thinks the ac is too cold - the ac clutch won't turn on. I have replaced a few bad ones of those. Other incorrect temp/pressure values can do the same - outside temp too cold, or ac pressures too low or high. You would want to verify all sensors are working correctly and make sure the system is fully charged (easiest sometimes to simply evacuate and recharge with the correct volume) - before guessing on a ~$150 part +labor+freon.
Here's a picture of a sample displacement valve

 

Same problem here. My issue is the climate control module mounted on the dash center console which needs replaced. Part was 800$ US last I checked and dealer may need to program a code into it for it to work. Part is easy to install, but expensive if needs programmed. I have chosen not to replace mine as my defroster and floor air work well enough. Good luck to you.