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2011 Alfa Romeo 159 SW 2.0 JTDm
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Discussion Starter · #1 ·
Hello,

I have recently repaired AC system (changed compressor, condenser and drier, expansion valve) and filled with 460 g required type of gas and oil at AC garage.

The high side pressure gets too high, 20 BAR and more. Low side stays on 2 BAR. System is cooling, outside temp is +15 C.

The AC garage says the engine electrofan is giving poor performance when pressure on AC system builds. The dealer checked electrofan performance and says it is a blockade in AC system - probably the evaporator. The dealer have no explanation why the electrofan is not working on 100% on 10 + BAR high side pressure. Dealer also checked the pressure sensor on AC system. Sensor gives 20 BAR, manometer gives 21 BAR so that is +/- accurate. AC garage says it can not be a blockade because the low side has 2 BAR and the system is cooling.

My Alfa Romeo 159 has dynamic electrofan - there are no 1., 2. speeds but frequency controlled as ECU requests. The RPM gets higher if I turn on the AC to max. AC garage says it is not enough. Dealer got it performing up to 70% of its max rpm.

The AC system high side should be no more than 15 BAR. (I guess, dealer did not specify yet)

I attach the image of my oem electrofan from dealer.

My AR model is Alfa Romeo 159 My11 (2010-2011) Sportwagon ((939_) Diesel 2.0 Jtdm (939Bxr1B) 100Kw/136Ps)

Any ideas what to look for and what to check? Electrofan performance seems a little off for me, but dealer says it is OK.

Line art Auto part Diagram
 

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They never go 100% for just AC. On cars with just 2 speeds for the fan, they use 50% only gor the AC and high speed is reserved for engine near over heating.

Did you fit original or aftermarket parts? from what you describe, there is too much gas in the system, as the 10:1 ratio between high and low side is spot on. If there is a blockage, the high side will go up, and the low side down. I am not seeing that from your figures. Too little gas and the low side would go down before the high side reaches 10 bar. but you have the high side rising and the low side not dropping.. too much gas.

Either they put more than 460 grams, too much oil (doubt that) or the new condenser/drier has a smaller content than the old one and the system isn't capable of 460 grams anymore. Simplest check: remove 50 grams of gas and see if pressures evolve in the right direction.
 

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forgot to add, I used to service big automotive Ac units, where the capacity of the system was unknown to me. I went with low/high pressure for filling after a repair t5o determine the correct amount. The smallest systems I did required 4.5kg of r134a, the biggest 30 kg. I would aim for 10 bar max in the high pressure side now that it's still cold, as pressures will go up some when it gets warmer.
 

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Discussion Starter · #4 ·
They never go 100% for just AC. On cars with just 2 speeds for the fan, they use 50% only gor the AC and high speed is reserved for engine near over heating.

Did you fit original or aftermarket parts? from what you describe, there is too much gas in the system, as the 10:1 ratio between high and low side is spot on. If there is a blockage, the high side will go up, and the low side down. I am not seeing that from your figures. Too little gas and the low side would go down before the high side reaches 10 bar. but you have the high side rising and the low side not dropping.. too much gas.

Either they put more than 460 grams, too much oil (doubt that) or the new condenser/drier has a smaller content than the old one and the system isn't capable of 460 grams anymore. Simplest check: remove 50 grams of gas and see if pressures evolve in the right direction.
Thank you! The parts were not from a dealer so they are aftermarket. Will give your ideas to the AC garage to try them out.
 

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Discussion Starter · #5 ·
The problem has been resolved. The electric engine fan was functioning normally. The amount of gas was right. The problem was dirty and damaged engine cooling radiator. It is located right between the cooling fan and the AC condenser. So the AC condenser was getting very little air circulation as engine radiator was not letting it through.

Thanks!
 

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Discussion Starter · #6 ·
Hello everyone!

This is a hot summer, so the cooling issues are more likely to occur. And the above mentioned engine cooling fan problem is still ongoing.

Basics: engine electric fan cools down the engine if needed, everything seems OK. But when turning on AC on warm engine, the cooler fan does not kick in on a speed needed to cool down the AC system and as a result the AC blows warm air and the AC system pressure rises. The engine electric fan should be kicking in on high speed (I dont have 2 speed fan, it has dynamic resistance by %) but it periodically stops and starts on very low speeds that are not enough for AC system to function properly.

When driving it is OK, everything cools down as it should. But when stopped at red light or stationary, the cooling fan should sense the extra heat and kick in on higher speed but it wouldnt.

Garage has by now: a. checked the fan with MES, b. changed the fan control module (new and from another 159), c. electrician has checked and redone fan electrical connections, d. electrician has changed the AC system sensor on dryer.
AC garage has: a. checked the AC system, found the same engine fan "poor performance", b. tested the car stationary, AC pressure drops only when engine is held on 2000 rpm for a while and it seems electric fan kicks in to cool the engine and it cools the AC system as well. c. put the exteral fan in and extra cooling fan made the difference for AC system to function normally.

Next step seems to be engine electric fan change, although MES test shows that the fan can be turned on manually on full speed.

Any ideas what to look for?

Thanks!
 

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Discussion Starter · #9 ·
Hi, is there any update on this? I have pretty much the exact same issue
Right now we are changing the engine electrofan to another used one for tests, I will let you know if we succeed (or not).
 

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Right now we are changing the engine electrofan to another used one for tests, I will let you know if we succeed (or not).
How did changing the fan go?

Mine has been in the garage and they were unable to find any mechanical faults. They also tried changing the fan relay but the problem is still there.
 

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Discussion Starter · #11 ·
How did changing the fan go?

Mine has been in the garage and they were unable to find any mechanical faults. They also tried changing the fan relay but the problem is still there.
For 3 weeks the car was at the Alfa garage, they tested the fan, the ECU and other wiring for error but found none. After that we got another one my11 with 2.0 jtdm and normal AC/compressor performance and compared them both at the same time. The other one has oem fan and (hopefully) the compressor too. Both AC systems got 18 bar and were working fine. After a while my AR dropped the AC pressure to 9 bar and the cold from AC was gone. The other one was still holding on 18 bar and producing cold.

The latest thought for now is the compressor fault - there is a valve which lets more or less cold in the system and it gets stuck. Electricians say that AC system is getting either too high or too low temperature - and rarely just as much as needed.

Next week I have booked AC garage again. There is a big chance that my 1 year used AC compressor will be changed to a new one...
 

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For 3 weeks the car was at the Alfa garage, they tested the fan, the ECU and other wiring for error but found none. After that we got another one my11 with 2.0 jtdm and normal AC/compressor performance and compared them both at the same time. The other one has oem fan and (hopefully) the compressor too. Both AC systems got 18 bar and were working fine. After a while my AR dropped the AC pressure to 9 bar and the cold from AC was gone. The other one was still holding on 18 bar and producing cold.

The latest thought for now is the compressor fault - there is a valve which lets more or less cold in the system and it gets stuck. Electricians say that AC system is getting either too high or too low temperature - and rarely just as much as needed.

Next week I have booked AC garage again. There is a big chance that my 1 year used AC compressor will be changed to a new one...
Thanks for the update, I really hope this solves it for you. Please let me know if it works as I will no doubt instruct my garage to do the same if it works for you.
 

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For 3 weeks the car was at the Alfa garage, they tested the fan, the ECU and other wiring for error but found none. After that we got another one my11 with 2.0 jtdm and normal AC/compressor performance and compared them both at the same time. The other one has oem fan and (hopefully) the compressor too. Both AC systems got 18 bar and were working fine. After a while my AR dropped the AC pressure to 9 bar and the cold from AC was gone. The other one was still holding on 18 bar and producing cold.

The latest thought for now is the compressor fault - there is a valve which lets more or less cold in the system and it gets stuck. Electricians say that AC system is getting either too high or too low temperature - and rarely just as much as needed.

Next week I have booked AC garage again. There is a big chance that my 1 year used AC compressor will be changed to a new one...
Hi again, just checking in to see if you have an update on your AC issue. Did a new AC compressor fix the problem?

Thanks
 
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