Transit mk6 bus 2.0tdci (FiFa) aircon problem

[_Anders_]

So I took my van to a garage to get the aircon fixed. The system had 3bars of pressure so it seems its not leaking horribly. So now they have changed the pressurehoses, dryer and the expansion valve. The issue now is that the high side pressure builds up too high and does not cut off until you have to switch the aircon off so it wont blow up.

My question is that does anyone know what the problem could be?

[knobby1]

Do they not have a high and low pressure switch..?? If so, the high pressure switch must not be working.

Lord Knobrot

[_Anders_]

Do they not have a high and low pressure switch..?? If so, the high pressure switch must not be working.

The high and low pressure switches both are new. So it seems the problem is somewhere else.

Does anyone have information what components control the high side switching? My two theories are a relay gone/going bad or a corroded earth somewhere. But if someone has first hand experience with this type of problem any advice is appreciated.

[_Anders_]

Now im sort of at a loss. The system is filled, new parts, and the diagnosis was that the radiator cooling fan control module might be broken. Or specifically one of the speed adjusting resistors inside is broken for the lower speeds. The only thing im puzzled about is that if the high side pressure switch is new and low side also, how does the system still operate without the fan and rising pressure? Shouldnt the high side pressure switch cut the power to the AC compressor when the pressure gets too high regardless of the issue?

[Altransit]

how does the system still operate without the fan and rising pressure?

It shouldn't operate, (except for a few seconds) without the fan running

the high side pressure switch cut the power to the AC compressor when the pressure gets too high regardless of the issue?

Yes it should

[wojciech]

If the fans are not running when the AC is turned on, the AC will not work properly, it will only turn on for a moment. To find out if this is the case, you can propel the van to high speed 60-70 mph and then turn on the AC. The natural rush of air then cools the condenser properly and the AC works properly.
The problem with repair is that Ford takes the fan assembly, resistors and housing as one piece, extremely expensive. You have to look for resistors - they are probably damaged - on ebay or buy some replacements. But first connect the fans directly to + 12V and check if they work.

[_Anders_]

Now its finally fixed.

And the culprit was the fan resistors.

So there is a pack of two huge resistors between the two fans for the air-conditioning condenser/cooling radiator. The power for the fans goes through few relays and get the signal from the PCM (and the other switches related to the system) i assume to power on. I tested both the fans with 12v so they were working. Then i removed the resistor pack from the fan casing and it was clear right away that its a gonner. It was so corroded that you could not see the parts in it. I tried to clean it gently but there was a component inside it and it was held only by corrosion and it fell off. I also tested the power to the resistors from the plug and there was almost instantly 13v in two of the three pins in it after i powered the ac on, so i assumed that that part was ok. Now to hunt a new resistor and It was harder than i thought. I could not find it new anywhere and had to resort to buying it from a scrapyard and i had to get the whole fan shroud with the fans to get the resistor. It seems the 2 fan model with 2 resistors is almost rare as hens teeth. But now its installed and the fans kicked right up after i powered the ac. So i call that a partial win.

But in conclusion it seems that the fan control does not have any logic to it regarding to the fans spinning or not in this model. If the voltage is going out it seems to think the fans are on. I still don't know if i have some part bad in the system because the compressor did not power off after the high pressure rising (or did the tech just play it safe at the garage and the high pressure switch didn't reach the maximum pressure limit? who knows..), but the both pressure switches are new, so now the system works and i am happy.


If someone knows where to acquire these resistors new, please tell me so ill get one for the future (2 fan model with 3cables/pins).


I just wanted to post this for future transit owners struggling with similar issues. Thanks for the suggestions and comments!

[wojciech]

If someone knows where to acquire these resistors new, please tell me so ill get one for the future (2 fan model with 3cables/pins).


I just wanted to post this for future transit owners struggling with similar issues. Thanks for the suggestions and comments!

New fan resistors? These resistors do not exist as a separate part - and that's it. You can't buy only resistors for any treasures. You carry a sack of gold luidors to the Ford workshop and come out with the entire kit: case, fans and resistors. The elegant gentleman usually has an expensive car. This is the only positive point on this matter.