Air-conditioning compressor
Q Next door’s 2015 Ford Ranger is playing up again. This time the aircon compressor clutch won’t engage. I can get it to by bridging the relevant relay terminals with some jumper wires. The problem seems to lie with the supply voltage to the relay as it is only reading 9.5 volts off load. It then disappears completely once the relay is connected. Do you think there’s a bad connection to the terminals inside the relay box?
I have found the system to be devoid of gas and 80-odd ohms of resistance between the negative terminal in the engine fusebox for the supply to the relay coil and the earth point on the nearside wing. I found a diagram online but it’s for a 2011 car and suggests a relay is being used to switch a relay which I thought was odd.
We got round the earlier eye watering cost of the EGR cooler failure by purchasing the manifold that allowed the fitment of the cheaper cooler. The manifold came from ebay at a cost of £80 and the cooler was an Amazon job at £60. Much better than the £650 plus VAT for the cooler that had a bypass valve that was redundant.
Incidentally, internet wisdom would have you believe the cooler we fitted is nightmarish job. Not sure why as I didn’t have any difficulty fitting it at all.
That reminds me, do you have a torque setting for the manifold nuts as they have worked loose once. Are you supposed to use new ones?
Anthony Pattinson
A The first move on Ranger would be to have the system leak tested using nitrogen and then if it does hold to have it re-gassed. The system will not allow the compressor to operate and so will not engage the clutch on the pulley unless all the criteria is met. This is a safety feature as spinning up the compressor without gas and the oil in the system would cause damage.
This would account for the second relay in the system. Autodata does only show one relay and this is in position either 4 or 7 of the underbonnet fusebox depending on whether the vehicle has the high or low specification system.
The exhaust manifold nuts should be renewed when refitting and the tightening should be done in three stages, 10Nm, 20Nm and finally 35Nm.