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Volkswagen New Beetle: 1998 and later Air Conditioning clutch Does not Kick On ?


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Last Post: Jul 26, 2014 12:25 PM Last Post By: marcotopez
betty bug

Posts: 30
Registered: 03/17/07
Air Conditioning clutch Does not Kick On ?
Posted: Mar 25, 2007 7:15 PM
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Hi Guys,

Bought the Bentleys book as suggested...Nice...

Where should i look first or what component for the air not to kick on ?
System is holding a charge .
Plug to compressor has NO power to it ??

Where would i go to next ?

Thanks............
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 25, 2007 11:21 PM   in response to: betty bug in response to: betty bug
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I don't have a wiring diagram in front of me, but trace the wire from the compressor back to the control head. If there are any components in between, work your way back and see if you have power to one, but not out of it. I have needed to replace a couple pressure switches. It purpose is to shut off power to the compressor if the charge is too low.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 26, 2007 5:30 AM   in response to: budpalumbo in response to: budpalumbo
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On the top pressure switch i have power to fan and can jump that but other point i would imagine to compressor does nothing...this has three point plug ???
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 26, 2007 9:36 AM   in response to: betty bug in response to: betty bug
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Sorry, but I'm at work now and looked a little more at the system. The car probably uses a digital pressure switch that sends a square wave signal to the fan control unit(also the compressor clutch). You need an osilliscope to test it properly. I have replaced several of those switches. It is located in the high pressure hose, near the firewall on the passenger side of the car. It can be removed without discharging the system. Make sure all the fuses are good first, there are about 6 that you need for that whole system.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 26, 2007 2:10 PM   in response to: budpalumbo in response to: budpalumbo
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Hi,

You say SIX fuses for the air ???
I only see one in the fuse box # 28 unless you mean
fuse links in a line ?
Do you know where all six are located ?

Where did they hide all these ????

Thanks so mucch !

betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 26, 2007 5:27 PM   in response to: budpalumbo in response to: budpalumbo
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Hi,
Do you know where you can get AC parts such as the pressure switch on the web ?
Thanks.
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 26, 2007 11:37 PM   in response to: betty bug in response to: betty bug
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Sorry, I'm at home again, there are several fuses in the system, playing major or minor parts. There will be a couple 30A fuses for the fan control module, and several smaller ones. They may not run just the a/c, so the diagram on your fusebox won't be good enough. If you look at the wiring diagram in the bentley manual, you can see all of them in it. It will be easiest if you locate one or find its symbol in the key, and look at ALL the diagrams you need to, looking for a similar symbol. Remember, the fuses that say #3 and the ones that say #233 are in the same box. The first is 3, the second 33. The "2xx" number designates that the fuse is in the lower part of the fuse panel.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 27, 2007 1:14 PM   in response to: budpalumbo in response to: budpalumbo
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Hi,
I checked all the fuses and appear to be good !
What would you check next or what would be likely
to be the problem ???

Question- do the pressure switches just screw off ???

Thanks.....
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 27, 2007 1:23 PM   in response to: betty bug in response to: betty bug
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yes it does. it has a valve under it to keep the freon in.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 27, 2007 2:44 PM   in response to: budpalumbo in response to: budpalumbo
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So just put a wrench on it and turn it left...not right handed thread ??
Should this pressure sensor cost $60.00 ??
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 27, 2007 3:37 PM   in response to: betty bug in response to: betty bug
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Tried to jump the compressor like the book says ...
book says there is four prongs..
Mine only has three...
This is off the pressure switch...
One is power....good.
one is for fan...turns on..
one must be for the compressor...lights up but does not kick
the compressor ???

Does this mean it is shot ???

Thanks...
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 28, 2007 5:15 PM   in response to: betty bug in response to: betty bug
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The 3 wire, component g65, is digital. You need an osilliscope or digital meter to test it. The 4 wire one is a simple on/off switch. You have the 3 wire one, it is a tiny computer that has power, ground, and a digital square wave signal going out of it. The fan control module(also AC compressor control) processes the signal, and knows based on the frequency of the signal from the pressure switch if there is enough freon in the car, and when to turn the fans on. Jumping it or using a test light can damage it and/or the fan control module.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 28, 2007 5:29 PM   in response to: budpalumbo in response to: budpalumbo
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Wow... glad i talked to you....could have damaged it !!!!
Which fan is for the air ?
When i did jump it the passenger side fan came on and when the engine gets hot the same fan comes on.

Do i have a fan problem too ???
Thanks so much...
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 28, 2007 6:08 PM   in response to: betty bug in response to: betty bug
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They may both run, it depends on temperatures and pressure in the ac system. The control unit "sees" a change in the pattern that sensor puts out. If it was 90 outside and your engine was hot, both fans would probably run.
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 28, 2007 6:43 PM   in response to: budpalumbo in response to: budpalumbo
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Pressure switch--- Removed it today like you said to.
Do not understand why my Bentley book shows the four prong and the Chiltons and its a three prong plug ?

Waiting for switch i ordered and will try that and see if compressor kicks on !

If not, where would you suggest to go next ?

Thanks again for your time !!!
wohlfarth

Posts: 1,745
Registered: 10/31/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 29, 2007 10:43 AM   in response to: betty bug in response to: betty bug
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Attachment M87-0012.gif (19.1 KB)
Seen and noted. This is a good thread and I have already made a note to add details on the 3-pin pressure sensor (G65) in the next edition of our New Beetle paper service manual. I'll add a little bit to the good information that budpalumbo has already shared.

I'm going to attach a gif file showing the 3-pin A/C pressure sensor (G65).

Below is the factory information for testing the 3-pin sensor. It came from our eBahn subscription product.

---------------------------

High Pressure Sensor G65
Function

the High Pressure Sensor G65 transmits a square wave signal to Coolant Fan Control (FC) Module J293 at a rate which varies according to the refrigerant system pressure.
The signal from High Pressure Sensor G65 is processed as follows:
Based on the pulse rate transmitted by the High Pressure Sensor G65 , the Coolant Fan Control (FC) Module J293 determines the A/C refrigerant system pressure and controls the function of the A/C Clutch N25 and Coolant Fans accordingly. For example:
Switches the Coolant Fan V7 to the next higher speed when pressure in the refrigerant circuit increases.
Switches off A/C Clutch N25 when pressure is excessive (for example when engine cooling is insufficient).
Switches off A/C Clutch N25 off when pressure is too low (for example with low/no refrigerant).
The signal generated by High Pressure Sensor G65 is also provided as an input to the Motronic Engine Control Module (ECM). As the amount of torque needed to drive the A/C compressor varies according to the refrigerant system pressure, the ECM processes this signal in order to enhance engine performance.

High Pressure Sensor G65 , multi-pin connector assignments Contact 1: Ground (GND)
Contact 2: Square wave signal (output) to Coolant Fan Control (FC) Module J293 and Motronic Engine Control Module (ECM) J220
Contact 3: Terminal 15 (ignition on)
Note:
A/C Clutch N25 is switched off when connector - B - is disconnected.
(sw note: Connector B is the 3-pin harness connector for G65)

High Pressure Sensor G65 , electrical checks Check voltage and ground supply to sensor using wiring diagram.
Check wiring for short to one another.
Check wiring for short to B+ and ground.
Check wiring for short circuit between High Pressure Sensor G65 and Coolant Fan Control (FC) Module J293 using wiring diagram.
If no wiring faults can be determined, replace High Pressure Sensor G65 .

--------------------------

I'd like to find out if the G65 was installed from a certain date, or with a certain A/C system (digital climate control?).

Betty, let us know what year your New Beetle is and if it has digital climate control. Also what engine size and transmission type?

Also, be sure to replace the O-ring on the pressure switch. The factory specifies "always replace". The spec for the O-ring is "10.8; 1.8mm". Tightening torque of the switch is 5 Nm (44 in-lb).

I'll continue to watch this thread and contribute if I can.

Stan Wohlfarth
Service Manual editor
Bentley Publishers

Message was edited by: wohlfarth

betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 29, 2007 4:12 PM   in response to: wohlfarth in response to: wohlfarth
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Hi,

Lots of good info in this Post !!!
I kept looking back and forth from book to car
for the four prong plug ...

Its a 2000 Beetle
2.0 engine
Five speed transmission.

As for digital air system , how do tell ?

Thanks SO much again !
betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 29, 2007 4:15 PM   in response to: betty bug in response to: betty bug
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If you mean DIGITAL readout inside the car then the answer is no.
Its the old push button , turn dial !
wohlfarth

Posts: 1,745
Registered: 10/31/03
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 29, 2007 4:21 PM   in response to: betty bug in response to: betty bug
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Digital A/C systems would have a digital temperature display in the A/C and heating control panel on the dash. From what I can determine, New Beetles did not get this system, known as Climatronic. The Golf/Jetta/GTI and Passat models did though.

Check and see if your control panel looks like the one on page 87-21 of the New Beetle service manual.

Whoops, just saw your last post, it sounds like you just have the mechanical A/C controls.

Does "five speed transmission" means it's a manual transmission?

Thanks, Stan

Message was edited by: wohlfarth

betty bug

Posts: 30
Registered: 03/17/07
Re: Air Conditioning clutch Does not Kick On ?
Posted: Mar 29, 2007 4:31 PM   in response to: wohlfarth in response to: wohlfarth
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Sorry about that...
Five speed is a MANUAL transmission... My car....!
Did not think about the automatics ....

Thanks..

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