Obvious thing to do to test is to turn temp down to minimum and see if it blows cold. (air con working) Then to max, if it blows hot then blend motors are working. My air con condenser has a leak so I've switched air con off (light on!) until I can find a good one. Perhaps I don't need to. Is there a cutout that stops the pump coming on if gas pressure is low?Nah, it won't kick in if it's too low.