Today, I took the radiator out of my Disco2 to flush it and the system. Upon putting it back together and thoroughly bleeding the system, I noticed a heavy ticking that seems to be coming from the aircon pump that was not there before I drained the cooling system to flush the radiator etc. I have ran the vehicle for near on an hour and bled the system twice now having drained the system for a second time in case I did something wrong in filling the cooling system. The heavy ticking will not go away. The vehicle will produce very hot air be it with or without the aircon. And it will produce cold air if I switch the aircon onto cold. I was wondering if the aircon system may have too much freon in it, but I have not put any more into the system either before or after the re-fill of coolant for the radiator.

Any ideas????

 

Well, I finally got to the bottom of the heavy ticking. It was the 80mm idler pulley. Replaced for around $45 thanks to Atlantic British and hey prosto, silence again.

 

There is a barely audible ticking from the ABS WABCO modulator as a rule. Why? I haven't a clue - but it's been there on all trucks I've listened to and even from new!