AC Quick Disconnect

[Beach_Dude]

My newly rebuilt AC system is clogged, again. Perfect time for summer.

I'm fully charged with High PSI being well over 350 and Low is -10, clearly indicating blockage or failed expansion valve; which is brand freakin new!

Pretty ticked off in consideration that every time I do an evacuation then recharge, I'm paying for labor. Not forgetting how difficult it is to dissasemble the front razor grille to get to the dryer, removal of radiator for enlarged condenser, etc, all just to do a flush.

Removing of the evap & expansion vale is easy. But, to do it all over, again, and again, WTF am I missing?

Two questions:

1. I removed the internals of what seems to be a Ford/Cougar/Mustang Disconnect. I assumed this is only for assembly at the factory and serves no purpose for us?

2. On the new York Compressor, I did flush the compressor with the PAG/ESTER oil multiples of times, until no signs of the PAG was visible. Isn't that enough?

Does anyone has any ideas?

Should I simply flush the system, replace the dryer & expansion vale again, with fingers crossed, or is there something else I'm missing?

[wiley-moeracing]

what are the high and low pressures? 350 is high but you may not be getting enough air flow over condenser if front of radiator. Ideally your high should be 175-225 area with lows 30-40 area. if there is a clog in the system your low should have a vacuum or close to it.

[Beach_Dude]

Exactly. I have -10 psi, being a vacuum on the low.

[Beach_Dude]

I should say one other note to make.

During startup of compressor, you can see flow start on the sight glass. Then obviously turns solid/fluid, no bubbles.

Being that the clog or expansion failure is clearly past the sight glass.

[Mikel]

If you minimize exposure from the outside to the dryer, you can probably keep it. IIRC the expansion valve is just outside the firewall. You could remove it, blow it off, reassemble/vac/recharge and hope for the best.


I'm puzzled as to why a system with all new parts keeps generating debris, but you could probably install an inline filter.

https://www.zoro.com/supercool-ac-compressor-filter-universal-13128/i/G2718441/

[Beach_Dude]

The expansion valve is directly connected to the evaporator, under the dash. It requires dropping the entire ac unit, undoing the black tape, removing/reinstalling unit.

I ordered another drier just in case... Better safe than sorry, especially since it has a filter built in. This is why I don't think a filter would help.

Could there have been left over pag oil which causes the clogging?

Only reason why I don't think it would is because I cycled the oil at least three or four times to make sure it was all flushed.

Anyone else ever use one of those filters?

[Mikel]

Stupid question - Could you blow high pressure air from the low pressure side and hopefully send whatever debris you have fly out the high pressure hose, without having t disassemble everything under the dash?



I've never used that particular filter, but I've used others that go on the suction side.

[Beach_Dude]

No... Ac systems are close off from the outside environment, being filled with R12-134 Freon.

Any oxygen, nitrogen or moisture with cause the system to loose performance or deteriorate.

Also, I can't blow 350+ psi compared to what the compressor is putting out. Lol

Also, the dash is the easiest part to disassemble.

[SJTD]

I think he means through the refrigerant system. Maybe worth doing just to see.

Disconnect at the pump and at the sight glass and blow through into a coffee filter to see whatcha get.

[FSJunkie]

You don't normally flush compressors. The York compressor has oil fill plugs on the sump and is just like the oil sump on your engine. They are filled with 12 oz of oil into the sump and that is the only oil added to the entire system. All you have to do to drain it is loosen one of the sump fill plugs and turn the compressor sideways to drain it.

Flushing the rest of the system is easy. The compressor, expansion valve, and receiver/dryer just have to be removed since none of those items should be flushed. I just pour some flushing solution into the line and blow it through in both directions with shop air. I let the air blow through for a while to dry out the solution.

The expansion valve is basically just an orifice....a jet. It changes its size based on temperature. They sometimes have a thermal sensing capillary tube that must be installed in a certain location on the evaporator coil or evaporator outlet tube. Some expansion valves sense this temperature internally and do not have an external capillary tube. I believe most FSJ expansion valves are this type. There is no difference between an R12 expansion valve and an R134a expansion valve, though it is always good practice to replace the expansion valve when doing this conversion since expansion valves cannot readily be flushed.

Fully evacuating the system before charging is highly important. Remaining moisture will freeze in the expansion valve and cause a blockage. FORGET about the recomended charge level by weight. 2.4 pounds or whatever.....forget it. Leave the system off but let the vacuum in the evacuated system suck in refrigerant until it registers 80 PSI or so before you run the system. Then with the system running let it suck in refrigerant until most of the bubbles dissapear from the sight glass. A few little bubbles here and there is fine.

Honestly 90% of the problems I have seen on these older A/C systems are because the A/C technicians who were trained on the newer A/C systems don't know what the f^$k they are doing on these older systems. This is why I went down to Harbor Freight and paid $250 to buy the entire A/C servicing setup to do it all myself from then on.

[Beach_Dude]

Wait, Harbor freight has a full AC service setup for $250!?!?!

Do you have a link? That's cheaper than having AC techs evacuate then recharge!!!!

[FSJunkie]

Wait, Harbor freight has a full AC service setup for $250!?!?!

Do you have a link? That's cheaper than having AC techs evacuate then recharge!!!!

Uhhh, yeah. That is why I bought it.

Also because I took my Wagoneer to a shop to have them evac and recharge it and the tech tried to do it without even opening the service valves on the compressor because he didn't know you had to do that on older systems. I had to stand there and tell him how to do his job. He also ran my compressor with no charge in the system and ruined the shaft seal on the brand new compressor. $250 for the labor and another $250 to replace the brand new compressor he ruined. THAT convinced me to start servicing my own A/C.

All you really need is a manifold gauge set, a can tap valve, and a vacuum pump. You can do any A/C service you need to with that other than recover the refrigerant from an already charged system...you have to just vent it to the air. If you will be serviceing systems often, I recomend getting a 30lb drum of R134a rather than doing it with the little cans. It's easier than the cans, but the cans work perfectly fine.

Harbor Freight's basic 2.5 CFM vacuum pump is what I bought. It is $95 and has plenty of capacity for any automotive A/C system I have dealt with. It will suck the average A/C system down to a full vacuum in a minute or two. Quality isn't too bad. Mine has given me no trouble.

Harbor Freight's basic manifold gauge set is $60 and it gets the job done. I have one and have used it, but I prefer the manifold gauge set that I bought from Napa. It is higher quality with a better carrying case and is easier to connect and use. I'd recomend spending close to $100 for a decent manifold gauge set.

Can tap valves are cheap, like $5. DO NOT get the ones that punch a hole in the side of the can. I hate those. Get the ones that thread onto the top of the can. Hardware stores and Walmart have the R134a cans cheaper than auto parts stores. Sometimes you can find them for around $6/can. Auto parts stores can get you the 30lb drum. I often like to have the cheap little all in one charging hose to connect to one can at a time for topping off systems on a road trip. It's easier to throw a can and that little 12" hose in the trunk for a road trip rather than drag the entire gauge set and tap valve setup.

Then you need is to learn how to use it. I can teach you that.

[SJTD]

I've got one of those air powered suckers. Maybe 20 bucks. Works ok.

[letank]

you can even cheap out, autozone loans you both, the manifold and the vacuum pump, last time the vac pump was brand new. I bought the manifold.
good point on the 30lbs can.

As for the drier, I have been thinking of using a more modern plumbing, like the xj where the drier is inside the engine bay....

[JeepJeepster]

Whats the pressures when the system is at rest with the jeep not running? Do the pressures equalize?