Replacing the Air-conditioning Compressor

The AC compressor is mounted on one side of the Scorpio engine, normally the nearside, and pressurises the low-pressure gas received from the evaporator inside the car into the condensor-radiator mounted in the airflow.

In December 2004 disaster struck - the compressor suddenly seized solid. This almost caused the engine to stall and a cloud of acrid smoke trailed behind the car, fortunately only for a few hundred yards before my wife got home. The smoke was from the drive belt - fortunately on the 24V the compressor has its own drive belt so the AA man took that off to allow the engine to run. On the DOHC and Diesel models where the AC compressor is on the same drive belt, he could simply have unplugged the compressor from the controller - the electrical disconnection would have prevented the compressor clutch from operating at all.

Okay, I knew this was going to be expensive - the compressor on the Ultima climate control is a hefty beast - but it had been rattling ever since I bought the car and had lasted through 6 years of hard use and several leaks, so I could not complain.

It was now December. Now that the hot weather was over we could have left the compressor disconnected, but we had finally sorted out the whole system so that it didn't leak, and I didn't want an extended period of non-running because it could cause the seals to start leaking all over again. So it had to be fixed.

I rang for a quote from the usual Ford Parts UK - but they had bad news. A new compressor and clutch would be about the £450 mark - and this was without labour and gassing - so I looked elsewhere.

My usual Airconditioning guys  - Aircon Direct - quoted me for a brand-new Visteon compressor and clutch (exactly the same as fitted but without the Ford label) for £245. They recommended changing the receiver/dryer as well to protect the new compressor (£31), while labour would be £50 and the gas recharge £60. The total with VAT came to £453, as much as Ford wanted just for the compressor, so I stayed with John and Mark Orford for the work. They ordered the parts and Mark came over to me once again to fit them.

On the Cosworth, most of the work done on the compressor is from the underneath, so I jacked the car up and put the front cross-member onto axle stands so that Mark could easily move underneath. Fitting the top two bolts through the compressor was easier with the air-filter and MAF removed, and that was the work of a few moments.

The compressor is secured to the compressor mounting on the engine by four bolts that pass horizontally through the compressor body. The high and low pressure connections are on the rear of the compressor body with built-in seals, secured by a single torx bolt.

A rear three-quarters view of the Visteon AC Compressor. The four mounting boltholes are clearly seen on the uppermost face, while on the rear is the low and high-pressure ports with the single mounting bolt hole between them. With the compressor disconnected or the aircon turned Off the drive pulley turned freely, but with the clutch engaged the compressor was seized absolutely solid. Fortunately, unlike some other makes, Visteon compressors rarely make a lot of swarf before they seize - they tend to keep the system clean when they fail.

The air filter box and MAF trunking removed, this is a view down the left hand side of the Cosworth engine. The upper two bolts securing the compressor to the engine mounting have been loosened. The Gas connector bolt is being removed from the rear of the compressor. On the upper forward face you can make out the multiplug connector - the plug has been removed.  If the compressor on your car seizes then removing this plug is the easy way to disable the compressor safely, especially if you have a DOHC model that only has one drive belt.

The new compressor was raised up to the engine mounting plate and the four bolts wound in finger tight at first, then tightened. The gas pipes were refitted.

Then the old Receiver/Dryer is removed. One mounting bolt faces in towards the radiator and is a pig to remove.

The compressor bolted up and connected and the new receiver/dryer in place, now comes the moment of truth - recharging.

The new liquified gas is added to the high-pressure side of the system - the new receiver/dryer. Then the system was run and the vent temperatures checked ;

0.8^oC in an ambient of 13 C - that's good enough for me! :-) And so quiet! Over the years I had become accustomed to a clatter from the gas compressor, now the engine idle is smooth and civilised, so although I'm £453 lighter in the wallet at least the car sounds great!

Perhaps now at last I can have the climate control operating right through 2 years without work? Time will tell.

Thanks to Mark and John at Aircon Direct - top work as usual guys.

EricR