1996 Vision TSI (LH) AC Compresser

My son came back from school and said the AC on his '96 Vision TSI (3.5L
DOHC LH) was not working properly. I took a quick look and the AC belt is
completely gone! Based on the fact that the belt was only 2 years old and I
found some of the belt's rubber left on the AC compressor pulley, I suspect
the compressor may have seized.

Since I have only limited experience with automotive AC systems, I'd
appreciate some info from someone in the know. Here are the symptoms:

- The pulley on the compressor and the idler pulley both turn fine/smoothly
by hand.
- The clutch still energizes when the AC control is enabled and locks up the
with pulley
- I can't turn the clutch on the compressor or the pulley when it is
engaged at all by hand.

I am reluctant to install a new belt without knowing if the compressor is
working properly. Specifically, should the outer clutch be able to turn by
hand before it is engaged? How much force should this take? Is there any
procedure to determine what specific component has failed?

Unfortunately, the FSM is away at the school so I don't have it here to help
diagnose this problem. At this point, I suspect the system is still
pressurized or else the AC clutch would not engage. I also suspect that the
compressor may be seized since I can't imagine why a 2 year old belt would
otherwise burn up on the pulley and then self-destruct.

Thanks in advance for your thoughts. He is going back to school tomorrow
afternoon, so I'd like to do further diagnosis and know what is bad before
he leaves.

Bob

 

The compressor should turn easily by hand. It doesn't really matter
which component in the compressor failed as they are replaced as a
unit.

The system will need to be flushed. Compressor needs to be replaced,
dryer needs to be replaced and the metering device cleaned well if not
replaced (I would replace it).

Steve B.

 

Steve B,

Thanks for the prompt reply. This is pretty much what I thought as well
when I saw the belt had self destructed. I'll look for a rebuilt or
salvaged compressor to hold down the expense and pick up new seals for it as
well. If there is good news, it is that the component is easy to remove
since it is right at the top of the front of the engine compartment.

As to the suggestion of replacing the dryer, can't I just pull and hold a
vacuum once the repair is made since the system will only be opened for a
brief amount of time and was working fine prior to the lock up? (The goal
here is to minimize the expense since he is a college student and will pay
for the repair himself ... he just needs a few more years out of this
vehicle.)

It is too late to try to do anything before he leaves for school
tomorrow...I'll ask him to bring back the FSM in Fall since it should have
info on how much and type of oil I will need to add to recharging the
evacuated system. By the way, I know I need to take it to a licensed
technician to do the evacuation before I do the repairs.

Thanks again.

Bob

 

The problem here is that the compressor locked up. Many times when it
does this shrapnel is spread through the system. If you don't get it
all flushed out one little piece can clog the metering device or,
worse yet, eat the new compressor. My concern would be if anything
has made it to the dryer... They are almost impossible to flush out
and the time that it was open for flushing would most certainly
saturate the desiccant.

Steve B.