My wife brought our vehicle in for an AC check last week as it was no
longer blowing cold. The shop performed an electronic leak test and
found no detectable leaks. They evacuated & recharged the system,
(including addition of sealant, oil & dye) and "cleaned debris" out of
the compressor. The vehicle passed a 20 minute vacuum leak down test.
The AC worked great for about a week, then lost its cool almost
immediately. The shop is now saying that a black light leak test has
found dye on the evaporator core outlet indicating that a new core is
needed - cost $1200.
The shop is claiming that sometimes a re-pressurized system will cause
weak parts to fail (ie, evaporator core). I feel that they simply did
a poor job of testing during the first visit, and charged for
unnecessary services that didn't resolve the problem.
Would a core go that quickly without any warnings or indications during
testing? Do you think a black light test done on the first visit would
have identified the core as the problem?
It is not uncommon for a system to pass a vacuum leak down test but then
leak when the system is under pressure.
I don't agree with that statement. It had a leak when you brought it in
the first time, that's why it stopped working.
I feel that they simply did
Such as ????
The evaporator core was most likely leaking the first time the A/C stopped
working. The evaporator is buried inside the heater box and usually not
visible unless removed from the vehicle, this makes it very hard to diagnose
a leaking core. It would be almost impossible to find the leak with a black
light on the first visit as there would not be any dye in the system. Once
the dye is added to the system it takes time for enough dye to leak out so
that it can been seen with the black light. The smaller/ slower the leak the
longer it takes for the dye to become visible. A leaking evaporator is the
hardest type of leak to find. I would say that the shop who did the work
followed normal diagnostic procedures.
leak detectors will find false leaks and good parts can be replaced when not
needed. Normally when dye is installed, the shop should recommend that you
return in a week to see if any traces of dye can be found. (this should be
done at a no charge to the customer when you bring it back). Normally the
one time charge is an hour labor not including any failed parts found after
the completion of the dye test.
I have never heard of cleaning the debris out of the compressor, this was
probably something they just told you to make it look as if they did
something they didn't. If they did install a sealant, they may have caused
more problems down the road.
If the core is really bad it was bad when they first charged the system and
just didn't find it. That was more then likely your leak that caused the a/c
to quit the first time.
Either way you would have had to pay for the initial charge. Just
curious...how much did they charge you?
If they performed the testing in that order, they probably
wouldn't locate a leak electronically because there was not
enough refrigerant in the system to begin with.
I hope you mean 'condenser.'
Depends on how they measured vacuum.
A mechanical vacuum gauge is worthless. An electronic micron
gauge probably would have alerted them to a leak but not shown
them where it is.
Few shops use or know of using a micron gauge.
Very plausible. If it turns out that the bottom of the
evaporator is coated with leaves and other organic plant like
debris, you have no one but yourself to blame for the failure.
Locating a leak, especially an evaporator leak is a bit tricky.
Their procedures are not a bit outside the norm.
What do you mean "that quickly?" It was already leaking when you
first visited them last week. Why do you think the A/C wasn't
cooling to begin with?
It did. The dye is useless if there is no refrigerant to carry
it/if the system pressure is so low that the compressor won't
engage in order to circulate the dye.
Normal procedure on an empty system typically is, recover,
evacuate and recharge system, check for leaks with an electronic
sniffer, if none are found, add dye and send customer on their
way with the advice that a follow-up visit is likely necessary to
inspect for dye escaping the system.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.