[Supras] AC finally working right

[Bob Schultz]

I sent this information to the MR2 List but I believe the information is
relevant to the Supra also.

 

Bob

 

 

I just learned all kind of neat stuff the hard way with my wife's 91 Mr2.  

 

A little more than a year ago the original compressor died.  I think it
froze up due to a lack of lubrication, it was 14 years old with a couple of
recharges but no oil was added to the system.  I figure if refrigerant can
get out of the system so can some oil ant this is probably were it went.

 

Anyway the retrofitted system with a new compressor worked fine for about 3
months then suddenly quit on a drive to Atlanta.  I assumed that I must have
a leak but when I returned the system suddenly started working so I just
ignored the problem.  It is kind of hard to diagnosis a working system but
in hind site I should have looked deeper into it.

 

Last month the compressor started making some noise and suddenly failed.  I
checked pressures and of course there was none.  I called my supplier and
told him of the problem and he nicely agreed to warranty the unit and
shipped a compressor and a dryer.  Of course the compressor didn't come with
o rings and after several hours on the phone I had o rings and installed the
compressor.  Upon first firing up the compressor the unit made around 150
psi on the high side and a vacuum on the low side.  Obviously the expansion
valve was stuck so now I have to replace that too.

 

Every time I work on a Toyota I gain more respect for the engineers.  The
evaporator core can be removed by pulling the glove box, 7 screws and nuts
and a couple of lines.  

 

Some one out there asked if the core could be cleaned without recharging the
system and the answer is no.  The core on the car had a bunch of leaves that
somehow got through the cowl but really for 15+ years of use the core was
clean.  I wouldn't even consider looking at the core but I bet you could get
a vacuum cleaner into the core area if you removed the glove box and the
blower motor. but I digress.

 

There was a recall for corrosion on the expansion valve back in 1993 and
mine supposedly had the valve replaced but upon further reading of the
recall the dealer could inspect the valve (how the heck they were supposed
to do this without removing it is beyond me) and if the system worked they
could bill out an hour, install some oil and move on.  I doubt they did
anything but bill the hour because the expansion valve was rusted shut and
it had a date of late 1990 on it.

 

After a little of reflection and a New Castle or two I came up with a theory
that the reman compressor was probably ok but while it was trying to
compress the refrigerant it was pulling a vacuum on the low side and that
was too much for the compressor to take causing the failure.

 

I just finished the job and pressures are right were they belong and 40
degree air is coming out of the vents.

 

Long story short.  If you are retrofitting the system replace the expansion
valve.  They are $35.00 and I was going to do it when I first did the job
but I got lazy.  It only took an extra couple of hours to do the job right.

 

Bob