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Discussion Starter · #1 ·
My daughter has a 2008 SE and the A/C is not working. Pressure is 90 psi on high and low side - I believe that's in spec with compressor not running.

Cooling fan does not come on with ignition on and AC button pressed. Doesn't coming on after running the engine for about 10 minutes either (didn't have time to run it any longer). She hasn't had any overheating issues though. Then of course she takes short trips and it's not too hot here yet.

Most of the threads I read about A/C are related to cars with two cooling fans - this one has one. I'm assuming the system works the same however.

Fuses and the fuse block on top of the battery box all appear to be good.

If I understand correctly the fan not coming on with AC button pressed points to an issue with the fan control module (or fan itself). But can a faulty thermo switch affect this portion of the control, or is the fan coming on with AC button pressed independent of the thermo switch?

When I read the service manual it suggests checking the thermo switch to verify fan operation, then if that doesn't work to replace the fan. Is the FCM on this car integral to the fan? I've seen FCM's sold without the fan that are allegedly good for my car, but then I've seen fan assemblies that appear to come with one.

I know I have some more troubleshooting to do, but I'm trying to get ahead of it with this thread as I have limited time before a trip to fix this, so any help is greatly appreciated.
 

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A/C system

Correct, 90 psi on both sides means Freon is charged to right level when compressor is not engaged & spinning.
I know a thing or two about the A/C system in the older model yr cars. Not too sure if I can help ya with an 08. I believe yours does have a control module in the fan itself and is a common failure for cars that have the one electric fan.
There is also an ambient temperature switch that won't let the compressor engage I believe it's mounted under the cowl & drains.
 

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Discussion Starter · #3 ·
Correct, 90 psi on both sides means Freon is charged to right level when compressor is not engaged & spinning.
I know a thing or two about the A/C system in the older model yr cars. Not too sure if I can help ya with an 08. I believe yours does have a control module in the fan itself and is a common failure for cars that have the one electric fan.
There is also an ambient temperature switch that won't let the compressor engage I believe it's mounted under the cowl & drains.
Yeah, I wasted two hours looking for the thermal switch shown in my factory manual, but that doesn't exist. Then I found this thread, which I revived to hopefully get some help.

I can't believe there is so little information about these 2.5L single fan control systems considering they've been out there since 2006. My factory manual, at least 2 years into this change, shows the right equipment diagram, but labels the parts wrong (e.g. calls the FCM J293, which its not), and then proceeds to give completely bogus repair/ troubleshooting instructions.

The fan assembly is minimum $350 (probably dodgy quality) and looks like a royal PITA to fix. I'd like to know exactly what the problem is before making that commitment, but I can't find any wiring diagram or any description of the control logic. That makes troubleshooting hard.
 

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Discussion Starter · #4 ·
Bumping this thread because I'm finally getting around to working on the car after being out of town a couple of weeks. I got the OBD Eleven and found I have code P2612, which is a problem with the AC compressor regulator valve. On the Ross tech wiki they say if you have the 2.5L beetle to also check the 4 pin connector near the starter, but give no other info. Anyone know what connector that is and how it's tied to this valve?

Back to the valve... this is just an on/ off valve, right? I.e. not proportional. Regardless of the A/C being on or off there's only about .3 volts coming from the wiring harness. I assume that means a wiring problem or the computer is not instructing it to come on. Would the fan not running prevent the compressor valve from being controlled?
 

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A/c

Bumping this thread because I'm finally getting around to working on the car after being out of town a couple of weeks. I got the OBD Eleven and found I have code P2612, which is a problem with the AC compressor regulator valve. On the Ross tech wiki they say if you have the 2.5L beetle to also check the 4 pin connector near the starter, but give no other info. Anyone know what connector that is and how it's tied to this valve?

Back to the valve... this is just an on/ off valve, right? I.e. not proportional. Regardless of the A/C being on or off there's only about .3 volts coming from the wiring harness. I assume that means a wiring problem or the computer is not instructing it to come on. Would the fan not running prevent the compressor valve from being controlled?
I'm not familiar with your 08 year system but I do know for a fact that if your electric fan is not running or if you don't have air flowing through your condenser it will disengage the A/C compressor it's a safety feature to keep your compressor's over pressure plug from opening & cause damage to the compressor.
 

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fan

other folks in this forum had the same issue as you I remember reading something about it just don't remember exactly what was the title of the thread. Might want to keep searching the forum or google it.
 

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Discussion Starter · #8 ·
Read all the ones I can find on the subject, which isn't many. I linked one in my first post. One guy solved his problem changing the fan. Another changed the fan and thought he solved his problem, but in a later thread he said he went to all the trouble, it appeared to fix the problem, but it didn't. I've checked tdiclub, vwvortex, here - there's just very little info on this fan circuit. Oh well, I bought a fan and will plug it in to test before I install it. Bought a new compressor regulator valve too. Hopefully one or both solve the issue.
 

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A/c

I wouldn't go changing the compressor or regulator valve or dryer just yet there might not be nothing wrong with your system
my first guess is the electric fan module that's part of the fan.
 

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Discussion Starter · #10 · (Edited)
I had no intent to change anything before having a better idea what was wrong. Working on these beetles is too much of a PITA to do that. I also initially thought it would turn out to be the FCM.

The problem turned out to be a broken wire (power to the N280 compressor regulator valve) on the 4 pin connector under the starter. I fixed that and everything works.

For others who have this system and ask all the questions I and the few others I've found with this system have asked, here is what I learned...

The fan does not run with the ignition on and AC button pressed. It does not necessarily run with the engine on and AC on. I do not know what AC system parameters cause it to turn on at low speed, but I understand high refrigerant pressure will result in high fan speed (at what pressure that is, I don't know). The fan will turn on at 99C coolant temperature.

The 4 pin connector coming from the FCM has the following wires:

Red is power for the fan motor. This goes to fuse S163 (not S164 like every other system seems to be and all the wiring diagrams show), which is 80 amps and always hot.
Brown/ Black is ground.
Blue/ Black runs to fuse 5, which is a 7.5 amp fuse and is hot when ignition is on. This is power for the FCM. The pressure sensor (not swwitch) G65 is also on this fuse (blue black wire as well is power to sensor).
The green/ red wire is the control signal to the FCM. It is grounded when the ignition is off. The FCM has no other inputs/ outputs to the system, other than the 4 wires to the fan motor.

There is no thermal switch on this system.

The N280 compressor regulator valve is on fuse 32, which is hot when the engine is running and AC is on. Power comes to the N280 through the green/ black wire and returns through the red/ black wire. These run through a 4 pin connector under the starter. I believe the other two wires in that connector (blue and blue/ violet) run to the alternator (and are unrelated to AC system), but I did not verify.
 
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