A/C "explosion"?

You could shoot that block with a .38 and it would still be in one piece. The Camaro used these “H-block” expansion valves and these things are tough if nothing else. Very hard to visualize the amount of pressure it would take to crack one of these. I would really think some other part would pop first.

It is correct to conclude that overfilling would not lead a customer to comment on how well the system cools and for this to happen while the engine is off,well this is really an “X-files” type thing.

Expansion valves used to have that black tar like tape wrapped around them but I do not think it was done in an attempt to contain the flying pieces

OP you do write “I have bits of an AC expansion valve on my carport floor”

quote from previous link:

Some guy started a thread titled “Mystery object”, and he found this housing resting somewhere precariously in the bottom of the bay. Anyway, quote:

“Its insulation for aircon expansion valve. Indeed part 36. Less cooling from ac if its not on exp”.

“WoW, you can identify an expansion valve by looking at bits and pieces but profess ignorance in all other matters related to the automobile? I am starting to sense a bit of a troll.”

All right-thinking people await your apology to JudithHurst.

Points to oldschool and makes “people are pointing at oldschool and making drinky-drinky gesture” gesture.

Sometimes the people with “top” user ratings here need to be slapped down, and even more rarely it actually happens.

“a short while later there was a cartoonish sounding “explosion””

“the explosion was only in the creative mind of the writer.”

Right. Typical hysterical woman. You know how they’re always imaging explosions.

“I’d suspect lots of damage to the evaporator coil under the dash.”

I think it would depend on the car. On the Chrysler products I own, the TXV is fairly far removed from the evaporator, right up against the firewall. Looking at that solid machined hunk of aluminum, it’s hard to imagine it bursting. You’d think a rubber hose would go first. But I don’t know how VW does their aircon.

Did not the “expansion valve” … “expand” as it’s name implies?

I’m not familiar with this particular system but in general, I have seen some uncommon things happen. Anything mechanical can fail without warning at any time, friend of mine had an a/c pressure switch housing fail on his Ford truck with enough force to dent the hood. The key item described was the “copper color disc with green ring” which to me sounds like part of a pressure sensor, pressure regulator, blowout cap, ect…

As for the comments on the “cartoonish explosion” - that’s certainly highly probable. Given the structural failure under pressure with the low-frequency concussion being redirected towards the carport floor by the car body thus disrupting the attenuation and directional dynamics by the resultant reverberation it could very well produce a fairly impressive report.

My primary concern would be ensuring that none of the insulating or other materials got blown into the engine areas where it could produce mechanical damage, malfunction or catch fire. Also, do not ?run? the a/c pump (either in ?a/c? or ?defrost? settings) as it will likely be damaged or destroyed ? to allow safe operation in defrost/defog, the a/c pump clutch can be disconnected electrically if it is driven by a common belt.

I have an extra Merkur evaporator and expansion valve block lying around here and which I have stated is similar to the VW. A quick look at that assembly shows that the expansion valve can indeed pop out of the expansion valve block.

There is a small capillary tube on the expansion valve as per the norm and the other side has a short protruding tube about an inch long and if I remember correctly a reference has been made to a disc with a protruding tube.

On the other side of the block is a pressed in disc. Either one can come out so pick your poison.

But what if you “shoot that block with a .38”?

A .38 what? .38spl; .38-40; .38-55; .375 H&H; .375wtby? There’s all kinds of “.38’s” so how about being a little more specific.

Read up a few posts and take it up with him.

It is the refridgerant that expands not the valve itself, this is pretty funny. First and exploding expansion valve and now and expanding expansion valve.

I have no idea what so ever the revelance of this "quote from a previous link is’

What I do know is the OP professes no knowledge whatsoever about automobiles but then is able to call the bits and pieces she finds on the floor pieces from an expansion valve, I am commenting on the sudden accumulation of knowledge by our OP.If she is commenting on a story she read and simply thinks it may apply to her situation she should say so and not make it appear she has made some sort of expert identification.

More so than any thing else I don’t want other readers to believe that "explosions’ involving their AC systems are anything more than a very,very remote technical possibility.In fact I would not call them explosions at all,simply a rapid loss of charge. Never in 35 years of AC work have I come across such a situation. This situation is simply nothing to loose any sleep over. My objection is the overly dramatic attention getting technique used by the OP. You do not need to scare people by making them think their parked car is going to explode, and there is nothing they can do about it. Some responsibility should have been shown when using the word “explosion” as people with even less knowledge than you read thes posts and get concerned. Take the post from the man that thought the expansion valve expanded, these are the type of people I don’t want to get the idea that exploding AC systems are something to waste one second of time pondering.Use some discretion in your choice of words as impressionable people are reading and we have a responsibility as not to alarm them unnecessairly.You could have made your case without using any reference to an explosion, this is my point.Perhaps it is because I do know the power of the printed word I do refrain from using inflamatory language, it is simply not called for.Perhaps you take this time and expalin why you chose to use the word explosion. I do agree that it is an attention grabber and may get more people to read your post but the use of these type of words when not required is very irresponsible. You could have left “explosion” out of the title of your post and simply said you heard a loud nosie. Going for the benifit of the dramatic does have consequences.

I’m surprised that no one knew that a sidearm is an approved service tool. :wink:

Summer hasn’t even started yet…

Another case of a missing OP. Do you guys really need the caliber and bullet type explained? I suggest you take a weekend a pop some rounds off and see the difference in performance between pistol and rifle ammo. When you get tired of that you can work with jacketed and non-jacketed ammo, it is tons of fun but based on how many of you post about cars a little warning about where you will be shooting would go far.

She’s not missing. She got some information and some answers as well as a heaping helping of attitude from you-know-who.

Which post was it that gave her some type of answer,could not be one tied to your name because you are in the “stir up trouble” business not the car businesI figure my post telling her not to be so dramatic in describing what happened to be the best piece of advice she recieved. Going to a mechanic spewing drama does not help the mechanic find the root cause of your situation, this is the time to be factual and not embelish,not even a little.

I took about 2 months off from this board because I was sick of reading drama and arguments on what I assumed was a car message board. On my first thread back, I see I have missed nothing.

Once again, a newbie comes on with a car question and someone`s gotta give out the gears.

I think I`m going to stick to Tom and Ray and leave the message board alone.

What makes you think I was talking about you? Did you go back and compare your posts to everyone else’s in this thread?

Post comparison is how I came to the conclusion that I gave the OP the best advice, I certainly do not want to ignore someone or not give due credit.The mystery attitude person is your little secret.

Please stick around. We will in all honesty try to help you as much as possible. Granted, it can be tough at times without car in hand but we try.

The details about A/C not working originally or this O-ring problem that was allegedly found are not known to us but let me propose the following theory anyway.

You have seen the reference to a block type expansion valve and I mentioned having an extra A/C evaporator and expansion valve block for a Merkur. Same thing.
I took at look at the expansion valve block this evening and disassembled it.
This block is aluminum (soft metal) and the expansion valve is steel. The valve screws into the block and the threads are extremely fine cut and very shallow. As a matter of fact, it only takes 4 full turns in the threads to fully seat that valve. This is not much at all when those threads are so fine and shallow they can barely be seen from any kind of distance.

This valve is sealed with an O-ring in the block. What if someone replaced that O-ring and either overtightened it or did not tighten it enough? This could mean that the system will take a refrigerant charge and cool fine but it’s actually hanging by a thread. (pun intended)
At some point the aluminum (again, soft metal) just gave up and the valve blew out of the block. This discharge will be over in a couple of seconds and will be noisy in a muffled thump kind of way.

Just something for consideration anyway. If you could provide details about the original repair and which O-ring was involved that theory could be either proven or discredited.
Hope that helps anyway. :slight_smile: