A/C Troubleshooting - Clutch not engaging and fans not turning on -No ground to T4/2

[Keven]

So...I went through the AC Guide and slowly started figuring out what's not working. I need to recheck power at the T4 connector because I miss interpreted the guide. Regarding grounds I have continuity from T4 4 to ground but NOT from T4 2. How do I troubleshoot that? Is that my issue?

I have continuity through the clutch coil.

T14 connector checks out fine, I think that's ok.


Macro level issues : Fans and Compressor will not kick on. Freon level is ok. Fuses are ok. A/C button lights up. I have continuity through the coil (but no power getting to compressor). I swapped the G65 sensor and FCM with different units and no change (though both parts were used).

Any ideas?

 

[Keven]

Anyone?

 

[wrenchman30]

you have a older system, button, freeze switch, low pressure, high pressure, clutch, start checking in that order for power

 

[Keven]

So I'm only getting 5.5v to the clutch but after trying to jump it quickly with 12v, the clutch still doesn't engage. I do have continuity through the clutch.

 

[wrenchman30]

5.5 volts sounds like a relay is burnt up or a wire is green with corrosion, recheck your ohms in the clutch if you cant make it come on with power and ground it is open or the air gap it to wide, .015

 

[Keven]

Care to explain further? So just add 12v to the cluth and see if it clicks?

Air gap? I'll recheck the ohms.

 

[wrenchman30]

http://www.sanden.com/ model 4254 read the service manual will show how to check the air gap, sections 7 and part of 8,

 

[Bran Diezel]

You need to check for resistance on the clutch coil. Not continuity, it could be shorted out.

 

[Bran Diezel]

Btw, our cars have 12v( or more) at the clutch all the time, I went through this last year on here with a guy. Maybe I can search an old post to find what clutch should ohm out at but it was his coil shorted.

 

[TC282AVIATOR]

Chasing same problem as we speak, my clutch will not engage (2001 TDI ). Getting 8.8 V to the coil, coil Ohms out fine @ at 4.5 , Jumper coil direct from battery and it engages fine. Now chasing the lack of Voltage. Sanden .com sight very helpful thank you wrenchman30 .

 

[TC282AVIATOR]

Found S180 fuse (green 30A) above the battery had very slight terminal damage from overheating. A quick clean up of the terminals and my Rad fans are now operational as well as my AC clutch . Back on the road .

 

[Keven]

That fuse seems like a common problem, unfortunately mine seems to be just fine.

 

[Keven]

You need to check for resistance on the clutch coil. Not continuity, it could be shorted out.

I see. For the record, continuity and resistance are the same test? Just if the resistance is very low it's considered continuity right? I'll report back with the actual resistance.

Either way, isn't it strange that the voltage was so low?

 

[edjet]

This link was looking at the Basic Settings for the throttle needing to be reset due to power loss ( battery change / need of a jump start):

http://www.justanswer.com/vw-volksw...tle-air-conditioning-became-intermittent.html

Has to do with a NB, but should be similar to the Jetta.
Might be of some help....let me know

 

[wrenchman30]

follow the 12 volts in the wiring schematic check both sides of the switches somewhere you have a burnt up item or a wire that has been probed and is green on the inside of it, do a ten pound pull test on the wires to see if you can pull them apart, happy hunting