Jump to content

Joe Marconi

Pulsing Voltage To A/C Compressor, 02 VW Jetta

Recommended Posts

A 2002 VW Jetta arrived at our shop the other day, the customer complaint…no air conditioning. The system was fully charged so we started our diagnostic tests and found that there was a pulsing voltage to the a/c clutch. The fan control module would pulse a 12 volt signal every few seconds.


After a little research we learned that a faulty compressor clutch could be the fault. We ohmed the clutch coil and found it open. We replaced the compressor clutch and now the FCM sends a constant 12 volt signal and all is ok.


Maybe others have seen this, but it stumped me and my lead tech at first. Apparently, if there is a problem with the clutch coil, the voltage will pulse from the FCM.


It’s a good thing we did a little research to find how the system works before shot-gunning the problem.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Forum Topics

    • By ake11
      Curious which compressor you are using ? specs? happy with it?
    • By Junior
      Need to upgrade our spring compressor, older Branick model struggles with hefty springs and that’s just downright dangerous. Looking to upgrade but not sure about which unit to get. OTC-6591 StrutTamer or Branick 7400. The Branick unit looks stronger but I don't like how you can't get on top of the strut with an impact without using a swivel. Which one do you have, would you recommend something else? I'm wondering how these machines tame really high spring rates in things like Toyota Tundas and BMW SUV springs, things our current machine can't really do safely.
  • AutoShopOwner Sponsors