Yet Another Air Conditioner Thread

[sagacis]

I've searched the forum and the internet. I've read all the messages. I still need more information, and the local shops haven't been entirely helpful.

Last year, I replaced my Air Conditioner compressor with a Sanden rotary. At the time, I also replaced both of the directly connected hoses with new hoses. I replaced the receiver/dryer and upgraded to 134 (flush, vacuum, etc.) For nearly a year, everything was fine and I had cool (not cold) A/C.

A couple weeks ago, the air wasn't so cool. After playing with the charge level over a couple weeks, and injecting lots of dye (I always used dye-containing freon), I haven't found a leak.

The high/low-side levels are reasonable during charge (and the air gets a little bit cooler, I think), but after a few hours of sitting, the system doesn't cool any more. When I put the manifold on while running, it shows low high-side and low low-side. When off, I was showing too high a pressure, so I brought it back down to normal charge.

So... This could be a number of things. A giant leak like I originally though should be visible with dye, right? I've scoured the system and found nothing.

My current theory is a blockage in the system somewhere. Short of just replacing everything anew, I want to find the actual problem, but I don't know how to find it.

Should I just replace my expansion valve (and receiver/dryer of course) and hope that was the problem?

I'm always thankful for the responses on this board.

[hcoles]

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[khamul02]

Well, the xvalve is cheap so I would replace it. Rennaire tests theirs so I would suggest picking one up from them. Also, I would replace all of the hoses. If your system is leaking without showing where (with dye) it is probably those remaining old hoses. They leak 134, that is a fact. But I'm not sure if they would leak at the rate you are describing.

[tab tanner]

Sounds to me like you have moisture it the system, you need to evacuate the system and run a vacuum pump on it for 8-12 hours to remove the H2o. Your pressure should run 35-55 on the low and 150-300 on the high. Did you vacuum the system when you had it open?? Please advise

[sagacis]

Yes, I did evacuate the system when I had it open, but that's something I've been worried about, given the symptoms.

I like your suggestion, Tab, since I can do that before ordering a new TXV. I'll go re-evacuate the system. Do I need to replace the receive/dryer (which means opening system)? If I open the system, should I re-flush for fun?

[khamul02]

If you think there is moisture in the system you should replace the dryer. Also, no one want to hear but those old hoses are nothing but trouble for 134. Very few have had success with them. They are normally the cause of the "seasonal recharge".

[tab tanner]

No need to replace the dryer, just leave the vacuum on for 8-12 hours. As far as the hoses go I have seen them work quite well with 134-a, even if they leak your A/C should last 1-2 years between recharges. Check the front condersor fan motor they are prone to failure. And when you recharge the system put a fan on the rear window blowing air towards the condensor this is very important the rear condensor needs the engine fan to pull air over it, with the rear lid open this does not happen and you will see the high presure go above normal and the a/c will not work correctly. I have got the a/c on old 911's to 41 degrees in the center vent with the outside temps in the lower 90's. If you work with this system enough you can make it run very well. Let me know

[sagacis]

Update: I left it on the vacuum for a little bit less than 8 hrs (I'm impatient and have a timeline). I left it evacuated for about 2 hrs with no leak (I doubt I would have noticed it in that time, then recharged it. When I charge it, I put the lid down so the engine can pull air over the lid condenser. I got down to mid fifties sitting in the garage (it was raining outside). I'll drive today, but last year, that gave me 40 degree temps on the highway. Since then, I've also replaced my front condenser fan motor, so I'm hoping for the same.

If I still have problems, I'll move to next step of replacing the rest of the hoses, TXV and dryer.

[tab tanner]

2 hours is not enough time to remove the moisture in the system!!! Put the vacuum on overnight and let it work!!

[sagacis]

No, I pulled a vacuum for 7 hours and 50 minutes, not 2 hours. Sorry for the confusion, re-reading my quickly jotted message does make it seem like I was overly foolish.

[3.2 CAB]

How much dye have you put in the system? I have never really been a fan of the a/c dye since the 70's after finding out that the dye will plug an a/c system to almost being unusable ever again, without replacement of almost every part except the compressor and condenser. I have seen the dye look almost like an ICEE drink, it had turned to slush in the evaporator, expansion valve and all of the low-side hoses. I had to replace almost every component to finally get it to work at all. The first thing that concerns me is that you state, "injecting lots of dye" first off I believe that the rec/drier is probably now clogged from all of the dye. I have not used any of the dye compounds since then, as they do not act or have the same properties of freon or the R134A. The dye does not go through the liquid to gas stages as freon does. I have seen many a/c systems rendered useless because of the dye. I would flush the entire system, replace the receiver dryer, either clean or replace the expansion valve, evaporator core. Totally drain the compressor, flush and replace all of the oil for the entire system, flush the condenser, flush and clean all hoses. After all this is done. then I would pull a very long evacuation of the clean, newly oiled, freshly sealed system. Then charge with the correct amount of the R134A and hopefully it will be a vast improvement from even the first time when you had it converted. Just my $0.02 Good luck!

[sagacis]

Good to know. I have only put in dye that came with freon, but all freon I've loaded has had dye, so any removed freon has probably left dye. Sounds like a flushing will be in order.

I'll drive tonight to find out if it still works after a whole day.

[hcoles]

the "dye" thing... interesting - almost every AC place seems to add dye (the dye could be included in the r134 ro r12) and then have you come back to check for leaks... are we saying here that all dye types or some dye types are at risk of messing up an AC system? This seems like it just can't be true, otherwise very much AC work would be ending in some sort of disaster...

[kuehl]

Using the "correct" dye should not cause blockage in the system; there are some UV dye tracer kits that come with various dye types, such as dyes for: engine oil, radiator fluid, power steering fluid, ac systems, etc. Using the wrong dye, or dye carrier, could cause the existing oil in the ac system to sludge (ask me how we know that), or mixing oil types (PAG and Ester, or PAG and mineral) can result in a like problem.

Many expansion valve "problems" are the result of moisture at the valve rather than the valve itself. A 3 hour evacuation is usually long enough provided: (a) your pump is working correctly (fresh oil, cfm), (b) you do not leave moisture or air in the system .. while thinking you got them all out

[kepperly]

What do you guys use to flush the system with? and does anyone have a brief description of the process. I am going to replace the original nippon compressor with one that I have rebuilt to eliminate the dreaded black stripe
on the inside of the engine cover. I,m sure at 90 k mi. the carbon seal is history. The rest is new, rennair serpintine evaporator, lines, pro cooler, desert duty front condensor and expansion valve.

Thanks
KEITH EPPERLY
87 SLANT NOSE TURBO LOOK CARRERA CABRIOLET

[kuehl]

Years ago R12 (liquid state) was used to flush the system. Today there are flushing solvents designed specifically for refrigerant systems.

There are several companies that market flushing solvents, machines and small kits. These products can be purchased through Big Box Auto Stores or through WE'LLBEATEVERYONESPRICEEBUTWEDON'TKNOWJACKBUTWESUR ECANCOPY web sites.

At the low end of the range is your simple aluminum canister (size of thermos bottle) you fill with flush solvent, charge with air and shoot through the system, prices typically under 100 for the canister and hose, and under 30 for a quart. On the extreme end are dedicated machines with solvent, filters, pulsing cycles, etc. , prices starting at 2500 and up.

The basic procedure, with a discharged system, is to disconnect the components, and flush the hoses, evaporator, and condenser(s); you don't flush compressors, driers, accumulators, exp. valves, orifice tubes, solenoids or pressure switches. After flushing you blow out with air and do a deep evacuation.

[3.2 CAB]

Actually, when R-12 was the primary gas used, the proper flusher was R-11, it came in the orange 30lb. jug. It was actually a liquid that really did flush the system, but it did evaporate and dissipate very quickly once out of the system. It did a really nice job of cleansing the system of pretty much all contaminants. I still have a jug or so, and I have not seen it for sale lately.