Non-working AC thread #3141592

[wwest]

Looks suspiciously as if PO did a DIY conversion to R-134a without the proper procedure of removing the R-12 and oil. My understanding is that mixing the two results in forming an emulsion.

Pay $200 to a professional shop to work from scratch for a conversion. And yes, replace the drier..

Oh, and yes, add a Red Dot trinary pressure switch, your Porsche does not have the high pressure relief valve as below.

It appears that Porsche might have expected the non-barrier hoses to work in the same manner. Certainly appears as if they were correct

From somewhere on the internet:

Suction Side Pressure Relief Valve

Some 1994 and later model Fords may exhibit a repeated, low charge condition with
no leaks found. A suction-side pressure-relief valve, which opens prior to the pre-set
pressure, may cause this condition.

The suction-side pressure-relief valve is designed to open at @ 250 PSI. This is to
prevent damage to the evaporator from excessive, static refrigerant pressure that
develops when the vehicle “heat soaks”. A “heat soak” condition occurs when the
engine is at normal operating temperature, the ignition is turned off, and under-hood
temperature increases. This could cause the static refrigerant pressure to exceed the
burst pressure limit of the evaporator. With a static refrigerant temperature of 150º F,
the static pressure for R134a is 264 PSI. Most evaporators will experience damage
when static pressure exceeds 250 PSI. At such pressure, the valve opens and
dumps refrigerant to the atmosphere.

The pressure spring inside the valve is subject to rapid temperature changes as the
air conditioning system is cycled on and off. The constant changes in temperature
(from warm to cold to warm) can weaken the spring, allowing it to open below 250
PSI.

Suction Side Relief Valve
Discharge Side Relief Valve
.


4S349

[wwest]

http://www.4s.com/Upload/Four%20Seasons/documents/Tech%20Tips/English/4S%20349%20SUCTION%20SIDE%20PRESS%20RELIEF.PDF

[GH85Carrera]

One request to Pato911, please after you do whatever you happen to do, let us all know how it worked.

If we can get all the AC threads to be finished with what the owner did and the results achieved it would help eliminate the debate. Good bad or indifferent, please report back with results of your project and what you did.

[wwest]

Originally Posted by COLB

That is not necessarily true.

I am happy with my $300 results -- and have working A/C. Yes, that is a sample of one.

But I doubt I experienced an A/C miracle.

Have you tried Bob Tindal's suggestion for additional engine cooling in stop and go, slowing moving traffic? It appears that technique might also be an aid in enhancing the A/C operation in those same traffic conditions.

If you try it and it works you might wish to take it a bit further and wire up a simple 12 volt relay, energized by the compressor clutch power and use a N.O. contact set to ground the engine oil temperature sensor signal going to the cabin heat controller.

[COLB]

Without question, the effectiveness of a "minimum" conversion will depend on the condition of your existing system.

If everything looks corroded, bent, and as damaged as your drier, the likelihood of achieving good results goes down.

As to kuehl's estimate of removing hoses to clean them -- that would be insanity. If you are going to pull out your A/Cs hoses, it would be foolish not to replace them with new hoses.

To wwest's point, there are oils that are compatible with R134 and the residual R12 lubricants in your system.

If you want to spend $3k on the A/C, you can get great results. No doubt.

Is that necessary to get a working A/C? Maybe not, depending on the condition of what you have, and your expectations.

[crownarch]

Originally Posted by wwest

Looks suspiciously as if PO did a DIY conversion to R-134a without the proper procedure of removing the R-12 and oil. My understanding is that mixing the two results in forming an emulsion.

Not to turn this A/C discussion into a pi**ing contest but, yes I had the R12 vacuumed out, followed by flush of system less the TEV and compressor. Removed what I could of the old oil from compressor and replaced with 6oz of ester oil. I am not concerned now what/where/when it leaked as that is behind me. What I was trying to share is my experience, what I am doing to make my A/C better to meet my needs and put it behind me. End of story.

[wwest]

Originally Posted by crownarch

Not to turn this A/C discussion into a pi**ing contest but, yes I had the R12 vacuumed out, followed by flush of system less the TEV and compressor. Removed what I could of the old oil from compressor and replaced with 6oz of ester oil. I am not concerned now what/where/when it leaked as that is behind me. What I was trying to share is my experience, what I am doing to make my A/C better to meet my needs and put it behind me. End of story.

I was addressing what the PO might have done, are you the PO?

[crownarch]

My apologies, I incorrectly misread the beginning of your post.

[wwest]

Originally Posted by crownarch

My apologies, I incorrectly misread the beginning of your post.

Okay....

[cabmandone]

If your evaporator coil and condenser are dirty/plugged, you will see a difference in the pressures and the suction line temps. If you can get to both sides of your evaporator, check the temperature drop across the coil. That will tell you if you're cooling properly. And again, check to see if you have condensation on your suction line. If you don't, believe it or not, you can have either a overcharge or undercharge situation. If you add gas and your suction side temp doesn't drop, you're possibly looking at a overcharged system. AC systems work on both pressure and temperature. To achieve proper cooling, you have to have not only the proper suction pressure but also the proper suction temperature. Blocked coils can change pressures and temperatures so that you don't have proper temperature drop across the coil. This could be a matter that you have to change your metering device (txv) because the txv you have is for R12 not 134.

[Pato911]

First, thanks everyone for the quick and useful responses. Like the Marines, you guys get more done before 9am than others do all day.

A couple quick clarifications/ updates:
1) The picture of the drier is very misleading. It is filthy! My car will never be a garage queen and has sadly not been washed in a couple weeks. The drier is straight with no bends, dents, etc. That said, it does look OE and I will plan to replace it.
2) As recommended, I checked the valves on the compressor and both seem to indicate the system still has pressure. At least some green fluid sprayed out on my car key.
3) Kuehl, with regard to your list of activities and time, thanks, but would I not spend equal durations changing everything out to a Kuehl equipment set and, as you advertise, result in a system better than OE?

It sounds like I have a project for the long weekend. I do not have any of the parts on hand (TXV, Drier, etc) but I can check pressure, evac, inspect, and flush the system. I will probably also remove hoses. The car is 27yrs old; I have no issues replacing rubber and other wear components as well as upgrading where technology has improved.

I can get new hoses made locally for ~$65/piece. Unless the committee has a better recommendation, I may just get a drier/ TXV ordered and plan to R&R hoses with reinstall planned for next week.

Are any of you in Houston and will to trade AC expertise/ tool use for food & beer?

[mike5876]

a leak pressure test will say there are no leaks while the hoses are hooked up check and replace the actual valves see if there is any oil residue under the caps

[kuehl]

Well Pato.... unless you got some camera lens distortion or some funky picture editing going on, I'd say:

1) That's quite a crush you got in the drier at the top, and
2) That's pretty dirty refrigerant oil in the site glass

[JAR0023]

I'd say rub not crush. There's little if any distortion to the metal. -J

[Bob Kontak]

Originally Posted by JAR0023

I'd say rub not crush. There's little if any distortion to the metal.

Not buying it. That thing is tore up unless flat does not count as distortion.

Moot as OP is replacing, I hope.

Originally Posted by Pato911

regard to your list of activities and time, thanks, but would I not spend equal durations changing everything out to a Kuehl equipment set and, as you advertise, result in a system better than OE?

The difference is, do you want to be genuinely cool in Houston or do you want to cut the heat a little with a well functioning stock system?

Originally Posted by Pato911

2) As recommended, I checked the valves on the compressor and both seem to indicate the system still has pressure. At least some green fluid sprayed out on my car key.

OK - "some green fluid" is different than I pushed the needle thing in and my friggin' fingers froze because I was doused with a non-stop spray of refrigerant.

Really, really make sure you still have a good shot of refrigerant in there. Otherwise, on your refresh procedure, you really need to locate the leak. It should be evident.

Get the car safely up in the air and prepare to get dirty.

I say, do the $300-500 refresh and get some practice. If you want to put one of Charlie's systems in, you will have some flight time under your belt.

[Bob Kontak]

One last point before I get my drink on. You can buy 30lb tanks of r-134 at the car parts store for circa $100. Do the math. That is like eight thousand 12oz cans of R134 that sell for $15+ each.

[kuehl]

This thread is a riot.

Crushed cans, flat tires, and the best....... 30 lbs x 16 oz = 480/12 = 40 ? noooo., = 8,000.
Yup, buy a 30 pounder and you can recharge every Pelican car (lacking barrier hoses) here for the next zillion years.

[Bob Kontak]

Originally Posted by kuehl

480/12 = 40 ? noooo., = 8,000.

Have you considered, perhaps, a rounding error?

[kuehl]

Yes Bob. We reviewed all the data. There were a few chad's. To be fair we including the chads and split the vote 50/50. And, just to be precise as possible we upped the 2nd decimal point 1 full value on the AFR for methanol because lambda always lies.

[Bob Kontak]

Originally Posted by kuehl

Yes Bob. We reviewed all the data. There were a few chad's. To be fair we including the chads and split the vote 50/50. And, just to be precise as possible we upped the 2nd decimal point 1 full value on the AFR for methanol because lambda always lies.

So, reading between the lines, you are saying that I am off a little in my can equivalence calculation?

I am ok with that. At least I was in the ballpark.