Tampa 928s

I am replacing my compressor with one I purchased from Roger at 928s r us he sold it as a core but said it came off of a working wreck. I have changed out the clutch and need to know how much ester oil to add, is it 4 oz? Do I pour it in the suction side than connect the hoses and what about the remainder of 4 ozs how and where do I place that. I am changing my expansion valve it’s leaking badly. I thought I would do all this, vacuum it down and see what happens. If it looks good I will replace the receiver dryer. Does this sound like a plan since my belt job is finishing up I though this was a good time. As a foot note I have a brand x flush kit but for what I read I would have to remove all the hoses to the Condenser and not flush it. Also I heard that I should use some type of mineral oil instead of the ester oil on the seals. Any feed back!

tomcat

I think ester oil if filling with r-134. Mineral if filling with r-12. I think the same with lubing the o-rings/seals. PAG (readily available with r134) is said to not mix well with r-12.

Add some oil to the drier. Also you can get ester oil in a can mixed with r-134 (if adding ester) to add into the system like you would the refridgerent. Specifications are available, but you need to make a judgement call as to how much is still in the system.

SteveG

I can't remember the amount w/o checking notes, but it was 1/3 to compressor, 1/3 to condenser and 1/3 to dryer.

Jim M.

You should put half the required oil in the compressor and half in the receiver/drier. BUT, unless you flushed the system you don't know how much oil to add. The total listed in the manual is for a clean and dry system. Your system has oil in the condenser, evaporator and the lines. I would recommend flushing the system first. If your going to go to all that trouble and expense it pays to do it right the first time. No offense intended.

Jim Mayzurk
93 GTS 5-spd

griffiths

6 fluid ounces and you can go as high as 8 fluid ounces.

You have two choices for getting the oil in the system, either you can do it or you can simply have your ac tech "inject" the oil after they pull a vacuum on the system... this would be the easy way. Otherwise you would just pour the oil into the suction port and the outlet port of the compressor using a smal funnel. You would pour a few ounces in the suction port until it won't take anymore. Then slowly rotate the outer hub on the clutch to turn the shaft and it will pull in the oil... repeat the process and bolt the compressor back on the car. You do not have to put oil in each component (drier, cond, evap or whatever) since the oil mixes with the refrigerant; the refrigerant carries the oil through the system.

The vacuum pull down test will only show you a "gross leak". It won't show you where the leak is. You need a dye in the oil and a glow light as well as an electronic leak detector to find the leaks. I would suggest putting in the new drier before you pull your vacuum. If for some reason the system rises back to atmosphere because of a leak, after you fix the leak and you pull another vacuum any minor humidity that may have found its way into the system will boil off when you properly pull a new vacuum.

If you have the time, equipment and materials and know how I would flush the system. You would flush all the lines when they are disconnected from their components. You would flush the condenser. The evaporator(s) are a PITA but doable with expansion valve(s) ((for dual air)) removed. You don't flush the compressor, drier or exp valve. (gee, I hope this guy reads the world famous flaming post on how not to flush a system.... in "detail")

Nonsense.
You can use the ester.

If this car was previously converted to R134a with PAG oil you would want to flush if you are going to use ester.... you need "enough" flush and you need to get it all out too. And please, do not overcharge the system. Use your gauges and go by a P&T chart.

fst951

I don't just sell parts, but I happen to believe that I do some of the finest A.C. work around.
Aside from being better off by resealing the whole system, here is the advice I will dispense.

Griffiths is entirely incorrect when he says that you can inject all the oil in the low side. That is a terrible idea as it can lock up a compressor. Do not do this!!!

Jim M is correct in his comment that you really don't know how much oil is already in the system, but I would guess no more than a couple of ounces. REPLACE the reciever drier anytime you open the A.C. system. They are cheap and critical to get good cooling and reduce corrosion to the a.c. system.

**** can the ester products. They aren't terrible, but they are not carried by freon R-12 as well as mineral oil. If you use R-134a, make sure to use a PAG 46 after flushing the system.

Ester was never approved by any major manufacturers for use of 134a.

Get someone that actually works on the cars, not just sells the parts. Good luck!!!

griffiths

I'll agree that we disagree. There is a SOP that you turn the hub several times prior to starting (this is SOP) to push oil out of the cylinders; I have watched a handful of fresh start ups where the DIY forgot to turn over the compressor I have never seen a failure from excessive oil in the compressor, hence turning before start up is a pre-caution. More common reasons for lock up on initial start are related to a DIY's charging by liquid through low side rather than the high side (washing out the compressor of any start up oil).

That is a tough call. I would rather error on too much oil, which in the worst case causes a performance loss due to evaporation saturation. Depending upon which year 928 you could be working with a system that had an initial volume of 10-12 ounces depending upon the year. Unless you have documented service records (and I would question them "knowing" about this industry), and given a vehicle that has been around the block, you have no idea as to how much oil may or maynot be in the system. If the vehicle has had refrigerant leaks in many instances the refrigerant may have pushed a good amount of oil out with it. And there is the OEM's "guidelines" for their amount of oil to add for a particular ac replacement component (reference bulletin page 87-24a): compressor 40%, evaporator 35%, condenser 15%, drier 10% (however they don't address hose lines) and there is the ac industries guidelines as well, for example they range from: 2-4 ounces for a compressor, 1 ounce for a drier, 1-2 ounces for condenser, 1-2 ounces for an evaporator, however they don't address total system length or volume and depending upon the size of the component or linear footage and size of ac hose the exact amount of oil may be more or less. So when a DIY is in the position to "guess" how much oil they should be adding and at the same time they have no fool proof way of knowing how much might be in there then it is simply a guessing game.

Years ago compressor remanufacturers and some new OE's use to ship compressors with a range of 2-4 oz in the compressor. However you never knew exactly how much because in most cases they did not note it. And as you know swash, wobble, rotary and scrolls compressors don't have dip stick (though Sanden does offer one however they are not easy to come by and we question their accuracy because of "wetting") so the client has no way of determining how much oil "may" or may not be in the compressor alone. Your only method of determining how much oil might be in the compressor is to dump out what is in there, measure it, include a factor for "wetting" (what wont' come out) and put it back it (SOP again).

So based on our experience (since 1984), and I'm not knocking yours, you would be safer to add more oil than not enough; in the worse case scenario you might lose some performance from saturation in the evaporator; I would rather minor lack in performance from an overcharge of oil than a locked up compressor in the case of not having enough oil.

Hey that's a great idea if you can convince a client on a budget however not always necessary. SOP is to replace the drier if:
A) changing oil types
B) questionable age of the drier
C) system contamination

Not so, you can find it on Volvo's and Saab's and with ester per the OE vehicle. There were many studies done on "retrofits" (as opposed to OE vehicles arriving with R134a) especially on fleets and it seemed to be a grey area as to whether wear was related to the procedure, the previous condition of the compressor or the type of oil (pag vs. ester). Though PAG is more prevalent to use on an OE basis (out of the box from the vehicle mfgr), or if you can achieve a "clean" installation (after a complete an thorough flush), ester will simply mix more readily with residual mineral oil as opposed to most readily available PAG's, this is a known fact: reference the original Texaco branded Capella R134a retrofit esters, the commonly found BVA brand and Castrol brands. Problems related to "oil" moving in the system with the refrigerant tend to be related to "miscibility" (single homogeneous phase); I would suggest that the viscosity plays a major factor as well, whether you are dealing with high system temperatures on the high side or low ones in the evaporator.

Here at our facility we have retrofitted plenty of vehicles using ester, primarily Porsche: 911, 928's (including the three I have owned), 944's and 964, and never had a problem. As well, we have marketed over 1,000 retro fit kits to the Porsche community of which approximately 1/3rd are repair facilities and 2/3rds are DIY's. If you search the forums for Dr. Bob of Jim Sims you will also find plenty of good results using Ester. If a situation came about where there was a problem relating to an "oil issue" usually is not the type rather a problem related to either system or installation problems (not enough oil or lack of oil flow).