Should the shop have known? (AC)

I'll admit... I don't know anything about car AC.  So learn me...

A friend's AC wasn't working (RX8 if it matters).  She dropped it off at a repair shop. They said it needed a compressor. 3 days and $1200 later it was fixed. 
 

1 week later it stopped working.  She took it back and the shop said it needs a new condenser.  $300 more.

Shouldn't a professional shop be able to diagnose the entire system at once when it is brought in?  Is the right way to do this to replace 1 part in the system then a few days later have to replace another?  Would a proper diagnostic have tested the entire system, or is it impossible to foresee that the condenser may have issues without first replacing the compressor?

Was this bad diagnostics, normal practice, or just bad communication?

Inquiring minds want to know...

Ac problems are really hard to diagnose. I work in automotive and did a fair bit of warranty analysis for AC systems.
 

there can be many weak points in a system, and the first one to show up gets fixed, when can then expose another weak point. Sometimes they're easy to find, sometimes they really are just guessing/firing parts. Compressor is pretty common, condenser is pretty common. 

AC systems failures can damage parts downstream from the failure. Kinda like if you wipe a cam, a new cam will get you down the road until the metal from the old cam causes its mayhem.

The knee jerk reaction for some AC repair shops is to replace the whole system. 

In reply to classicJackets (FS) :

That's fair. 
 

Just seems it would be easier if the pro would communicate that to the customer at the initial contact. 

IF the compressor was unable to create pressure prior to the initial diagnosis I can see the condenser being missed. Personally I have tested condensers independently with quickly built plates that fit the manifold, a vacuum and gauges dozens of times, production shops frequently do not go that extra mile. 

I think it's a combination of shop not thoroughly testing the rest of the system (likely the condenser was bad killing compressor 1), lack of setting expectations to accommodate their lack of thorough testing and lack of communicating that the vehicle is a 15-20 year old car that may exhibit secondary failures and even beyond.

All of that being said $1200 is steep for an AC compressor in my book, yet $500 is cheap for a condenser... $1700 for both WITH A WARRANTY seems pretty fair.

Also kinda surprised the leaking condenser wasn't found when the whole system was put under vacuum to dry it prior to recharge.   But if it worked for a week that's a reasonably slow leak.   I'm assuming they used dye or similar to diagnose the bad condenser and it isn't just infant mortality on the new Compressor. 

The newest RX8 is 12 years old now. IT's not uncommon that parts that passed pressure tests in the shop, out on the road under full pressure again fail. AC systems are some of the worst to try and diagnose without a come back. If you quote it all, you're ripping people off. If you don't, you half assed and can't fix a sammich. Damned if you do, damned if you don't. 

In reply to SV reX :

The flip side of the game is that I can make good coin if I just charge you $1200 to install a compressor and accept the risk of you returning with a failure; I will figure how to make it your problem. Odds are that a good system flush does save the rest of the components. But they are not going to guarantee it like the person who replaces the whole system will. 

I have had this conversation with someone who does AC for people who build hot rods. He recommends buying full kits like from Vintage Air, but will piece together a system from used OEM parts if that is what must be done. No warranty on plan B.

It is apparently not leaking- they think it's a blockage. I totally understand how a new compressor could increase the pressure and knock something loose that created a blockage. I just assumed there was a way to flush out the system and/or pressure test before installing the new compressor.

I think if I need one done I may consider installing all new parts for the whole system, then asking a shop to pressurize and charge it properly.  It would have been about a third of that cost (and it would be a whole new system)

I have heard that when a compressor goes it can send all manner of shrapnel through the system and that condensers and evaporators have developed passages that are so tight that it's nearly impossible to properly flush them out.  I can totally see that they tried to "get away" with flushing the condenser to save some money but something got knocked loose.  My concern would be that if there was enough of something still in the system to cause a blockage, has the system been pushing grit through the brand-new compressor?  If they recommended replacing everything and it was declined then I wouldn't fault them for that.  But if they didn't mention the possibility, I think they failed in properly informing the customer.  I'd ask them to eat the portion of the labor for evacuating and re-filling the system and I would want them to write a parts and labor warranty extension on that compressor.

In reply to wae :

They did not make a recommendation. Their only instruction from the customer was "fix my AC".

nocones said:

Also kinda surprised the leaking condenser wasn't found when the whole system was put under vacuum to dry it prior to recharge.   But if it worked for a week that's a reasonably slow leak.   I'm assuming they used dye or similar to diagnose the bad condenser and it isn't just infant mortality on the new Compressor. 

The condensor in my Volvo leaked badly enough to need a complete recharge after two days.  The top of it looked like I'd roadkilled a Predator from all of the dye from me adding refrigerant every so often (going on a weekend road trip and it's hot out? Charge it) before I had time to drop the cooling stack out to replace it.

It always passed a vacuum leak test.

Now let's say they never recharged it... and the compressor died in the fall or something, and they drove it all winter where wet weather washed away all the dye traces.  Where do you start?  Replace what isn't working, see if it works, and go from there.

In reply to wae :

You can't flush a modern condensor, sadly.  The tubes aren't tubes like a radiator, they are more like a grid inside.  Some of them have passages about hair sized.  Combine that and the fact that all of the tubes are in parallel... you can't flush, just replace.

Here's an older one.  The newer high efficiency models are much finer!

You might be able to catch that with a thermal imaging camera.  My $1400 camera is almost useful enough to see blocked tubes, but I'd really like one of those $5000 FLIRs.  That costs money though and my crappy camera was a gift.

Thanks guys. This has been helpful. 

I helped a friend service an ac system that had cratered the compressor. He pulled a screen out of the system that had caught a huge amount of shrapnel from the compressor disintegrating. Any service is only as good as the tech doing it.

In reply to TRoglodyte :

Most compressor failures I see are leaks or failed clutches.  That said, the general rule of thumb is that the condensor generally acts as a good filter at catching crud, but you should replace every component outside the firewall, and flush the bejayzus out of the evaporator and cross fingers that the condensor and expansion valve did catch it all...

Rx8s also have a valve under the dash that fails.  It's a crazy difficult job that shows as the compressor not having a delta p across it.  I'm about to do that myself.  

It shows as a bad compressor.  It isn't.

Good luck!

In reply to Olemiss540 :

Some people have the mindset, and some people TEACH the mindset, that if you sell work with the caveat that there may be more underlying issues, that makes you look incompetent.  Which IMO is completely bullE36 M3.

Vehicles are NOT simple things, a lot of things are interconnected.  That bad O2 sensor may have been hiding a failed converter that the computer wasn't testing for because it won't run the catalyst monitor if fuel trims are out of whack.  That dead fuel sending unit may have been hiding a light misfire caused by a worn camshaft, or an evap code caused by a leak or a failing solenoid, because misfire monitors and evap monitors don't run if the fuel level is under 15%.   The failed A/C compressor may have been hiding a failing expansion valve or a fan that won't run on high speed because nothing worked when the vehicle arrived.

You have to address what you know is faulty with the expectation that you ​​​​may uncover another weak link in the chain.

As we used to say, our crystal ball is at the crystal ball repair shop, so we can't know everything.

In reply to SV reX :

You are assuming the shop is both honest, and actually knows as much as they think they do. 
My experience, sadly, is that the average car owner, stands less than a 1% chance of finding a shop that's both. 
I know there are a few guys on here that run or work at shops that are, but using my personal experiences as a data point, well, it ain't likely. 

In reply to 03Panther :

No, it's the opposite. I'm not assuming the shop is honest and capable, I am assessing whether or not they are honest or capable so I can offer advice to a friend.

Based on the advice here, I'm gonna assume the best. Looks like it was pretty much normal practice (though the communication could have been improved)

It's not uncommon for any refrigerant system to have a secondary issue come up after the first part of failure is fixed. 

I will say it this way from the persepctive of a former shop manager and service writer.

If you take a look at the book time for a full diagnosis, dye test, leak test, etc, it's usually the same or more than the labor to just replace the condenser during the service.  I have to read the customer.  If they're a college student who just wants it to work for the loose change in his center console, you slap a compressor on it and explain to them that this might not fix it, or there might be something wrong.  Some people like the one-step-at-a-time approach to limit their potential investment.  (even though it almost always costs more in the end) Others just show up with a checkbook and say "replace my A/C"

I think the disconnect here is that the shop gave your friend the impression that this was "it."  It's fixed now.  Done.  That is a big no-no.  Customers need to know, and I mean KNOW that nothing like this is ever fully guaranteed to be a forever fix.  I can understand something like an oil change, new tires, or a fuel gauge sender having an expectation of being a once-and-done fix, but not A/C stuff necessarily.

The shop may have ignored an obvious thing, and shame on them, but I wouldn't jump to that conclusion.

In reply to Curtis73 (Forum Supporter) :

I'm not saying they did a bad job. I'm saying they did a bad job communicating and managing the customer's expectations. 
 

That's still their job. 

In reply to SV reX :

Effective communication and expectations management is one of the more difficult yet important parts of this field.