Automotive Air Conditioning Information Forum

tbirdtbird wrote: ↑Tue Jul 06, 2021 1:54 pm " I read that it was a way of checking correct charge volume"
Not really.

If you have an accumulator and thus an orifice tube, the flow is like this, as Detroit diagrammed:
comp-->condenser-->OT-->evap-->accum--> back to comp

OT and TXV are very different expansion devices

My apologies, you are correct. it is comp-->condenser-->OT-->evap-->accum--> back to comp.

Thank you all.

Paul,
I've read again the whole thread, I think it's undercharged. I know you've said the correct charge by weight is being installed, I think maybe it's not being done correctly.

If you are SURE the correct charge amount is being added, I think the orifice tube screen is clogged with debris.

In either case, I guess the actions I'd recommend are the same:

Recover the refrigerant
Open the line at the orifice tube, pull it out and look at it, clean the screen or install a new one.
Pull a good, deep vacuum
Charge to the vehicle sticker amount by weight

DetroitAC wrote: ↑Wed Jul 07, 2021 8:14 am Paul,
I've read again the whole thread, I think it's undercharged. I know you've said the correct charge by weight is being installed, I think maybe it's not being done correctly.

If you are SURE the correct charge amount is being added, I think the orifice tube screen is clogged with debris.

In either case, I guess the actions I'd recommend are the same:

Recover the refrigerant
Open the line at the orifice tube, pull it out and look at it, clean the screen or install a new one.
Pull a good, deep vacuum
Charge to the vehicle sticker amount by weight

I appreciate what you are saying. But I'm fairly sure it was charged correctly. Firstly I went to my usual guy, who is the most honest mechanic I know. But just to be on the safe side I went somewhere else the second time, but the result was exactly the same. I've ordered a new orifice tube (as they are low value anyway) when it arrives I'll evacuate the system and remove the old one (fingers crossed I can get it out without issue), and I'll post a photo of what I find, good or bad. And if you guys are willing, we can discuss it from there. Thanks very much.

DetroitAC wrote: ↑Wed Jul 07, 2021 8:14 am Paul,
I've read again the whole thread, I think it's undercharged. I know you've said the correct charge by weight is being installed, I think maybe it's not being done correctly.

If you are SURE the correct charge amount is being added, I think the orifice tube screen is clogged with debris.

In either case, I guess the actions I'd recommend are the same:

Recover the refrigerant
Open the line at the orifice tube, pull it out and look at it, clean the screen or install a new one.
Pull a good, deep vacuum
Charge to the vehicle sticker amount by weight

So it would appear you are correct...





But now the next question, what is this light brown coloured flaky substance that is the vast majority of the blockage (circled)? My first thought, could it be the drying material from inside the accumulator?? Your thoughts, as always, would be gratefully appreciated.

Why is the background color blue?
How much of that stuff is upstream from the OT you have to wonder

You can attach pic files directly here, no need to use photobucket

Piston coating is my guess, personally I'd put in new orifice,, pull good vacuum and charge up to sticker weight refrigerant. Maybe get few more years out of that compressor? Others might have a different opinion, it's just a money question, how long will you keep this car will inform your decision.

Oops, just re-read it's light brown, might be miracle in a can stop leak?

JohnHere wrote: ↑Wed Jul 07, 2021 7:18 am I was thinking all along that this was a TXV system. But it appears to be a CCOT system. If so, it's time to recover the charge, pull the OT, and examine it. If it's full of black gunk and particulates, then we have more problems to address other than replacing just the OT.

My thoughts: The debris came from your original compressor. Before replacing parts, you'll need to start with a clean system. That means flushing everything that can be flushed (evaporator, lines without mufflers) and replacing the rest. After flushing, I would install the following new parts: OEM compressor, condenser, accumulator, lines if necessary, and orifice tube. Then add the correct amount of DEC PAG, distributing the oil properly throughout the system, reassemble, evacuate well, and recharge to specs.

DetroitAC wrote: ↑Thu Jul 08, 2021 9:46 am Piston coating is my guess, personally I'd put in new orifice,, pull good vacuum and charge up to sticker weight refrigerant. Maybe get few more years out of that compressor? Others might have a different opinion, it's just a money question, how long will you keep this car will inform your decision.

Oops, just re-read it's light brown, might be miracle in a can stop leak?

Thanks for your reply. I will fit the new orifice tube when it comes and go from there. Whether I continue will depend upon the outcome. If I'm able to get some A/C, (even short term before it blocks again) will effect whether I spend any more money or not. We'll see.

Thank you all for your help, I feel I've learnt a little about how this system works as a result of your input.

If that stuff was in your bloodstream going to your heart. Would you want it to last just a few days. System flush is needed, or this will repeat itself and not be related to defective import parts.

It won't take long to clog a new OT