Civic AC Compressor

Four years and 40,000 miles after replacing the compressor, expansion valve
and receiver dryer on my 95 Civic EX, the compressor blew up witht a half
dollar piece of the housing departing the scene.
Last time I replaced a weak compressor, I flushed the system, but I did
not replace the condenser. I noticed comments, after doing an extensive
search in the archives, that the condenser can't be flushed because of its
crossflow design. Also, I had a problem last June with the compressor's
head pressure being to high (350 psi), either frome me adding a few onces
of R-134A too much or the compressor having some sort of internal
malfunction. Prior to my adding 6 oz of refigerant, the car was not
cooling properly. I'm wondering if Honda spiral compressors are
prone to failure or if not replacing the condenser last time finally
caught up with me? Any assistance in this matter would be greatly
appreciated.

 

Compressor explosion can be caused by overcharge. Overcharge usually doesn't
show up as high head pressure (that suggests a problem with the airflow
through the condensor), but instead causes the evaporator to overflow and
"slug" the compressor with slugs of liquid. The compressor tries to compress
the liquid and something's got to give.

I've learned through experience that the stories are true: an R-134a system
can't be properly charged by any method except evacuation and filling with a
measured amount of refrigerant. I can charge an R-12 system with guages, by
ear, by sight glass or by thermometer, but there is something different
about R-134a. (The link below suggests it is the reduced total charge makes
the margin narrow.) When I tried it by ear and guage, I went completely past
the proper point and never saw the cycling settle down, never saw the low
side drop... even though I was going very slowly. Then I started hearing
little slugs hitting the compressor and I shut it down until a pro could get
to it. Sure enough, I was several ounces over and with vacuuming and the
proper charge the system worked great. I don't know why 134a reacts that
way, but it does. http://www.autoacsystems.com/_faqs/detail/quick.html has a
decent description of the situation under the Recharging & Refrigerant
section.

Anyway, you can replace the compressor yourself but you should take the car
to a pro for the refrigerant side of things.

Mike

 

Thanks Mike, you made some very good and informative points. I suppose I
should also change the condenser, the expansion valve, and figure out a
way to add an in-line filter forward of the compressor? I am very worried
about debris migrating to the new compressor which is on order. With all
of the Honda's on the road you would think there would be more discussion
in this forum about cracked compressor housings. A co-worker told me his
wife's 99 Civic cracked its compressor housing. Also, I'm still not
totally following what makes the evaporator slug liquid refigerant to the
compressor, too much refigerant? Thanks again.

 

For the rehabilitation part, that is beyond my experience. I bet you could
get free advice from whoever can do the recharge service, though. It may be
that the system will have to be flushed to ensure the right amount of oil is
added when the compressor is replaced.

Too much refrigerant will slug the compressor, although there are reports of
excess oil doing the same. The concept is that in operation the evaporator
should stay nearly full of refrigerant without being overfilled. The less
full it is the poorer the cooling, but if it is overfull the excess spills
into the suction line to the compressor (ouch!). From what I read, even
small slugs can damage the valves in the compressor and larger ones can
break the compressor housing. Since the refrigerant in the evaporator boils
when the compressor is running, the boiling action can splash little drops
into the suction line before the level reaches the point where liquid is
actually flowing. Tiny splashes are no problem as they evaporate on the
warmer metal of the suction line. It's the larger gulps of refrigerant that
do the damage.

The situation isn't restricted to Hondas and isn't even specific to R-134a.
It's just that it is so much easier to overfill an R-134a system than it was
in the days of R-12. As long as the system isn't overfilled it shouldn't be
a problem.

My daughter's '93 needs more R-12; after I put my last can in her A/C I am
hanging up my guages. I can clearly do more harm than good on the new
systems.

Mike

 

I'm an air conditioning novice but if a filter were to be attached to
the system, shouldn't it be placed on the return line just before the compressor?

TIA

JT

 

Thanks again Michael and you're right Grumpy, I should have said upstream
of the compressor instead of foward of the compressor.