A/c

[Gawernator]

Hey Pelican, I was wondering what is the regular temperature that your 944's A/C blows air at? When I bought my 944 the air blowed but it did not cool, so I assumed all the freon had just leaked out. A small repair shop nearby pressurized the system and amazingly there are no leaks and the compressor and everything still works, even after sitting for a while. Recharged the car with 2.5 lbs of R-12 and the system was blowing 38 degrees Fahrenheit at its coldest. Today I was checking the temperature and it was getting down to about 45. Today was a hotter day with strong California sun and I was thinking perhaps that could affect the temperature? I'm just looking for what temperatures I should be getting normally.

[John_AZ]

I had my '88 924S with factory AC & R-12 inspected at the beginning of last season 2011 and the tech said it was full and the vent temps were 37 degrees. Still the same today.

John

[kuehl]

Assuming everything is "OK" with the system, lowest vent temperature is relative to outside ambient air temperature, thermostat has a max cold temp.

[Gawernator]

Thanks for the replies, I think the system is working OK.

[John_AZ]

kuehl,

I have another question for you if you don't mind.

Is it ever necessary to add oil to an R12 system if it is just serviced (no failure-25 YO car) and only a few ounces of R12 is added every 3 or 4 years?

Thanks,

John

[uvachief]

You must have the only Denso a/c compressor on the planet that didn't fail and leak.

[AaronM]

Originally Posted by John_AZ

kuehl,

I have another question for you if you don't mind.

Is it ever necessary to add oil to an R12 system if it is just serviced (no failure-25 YO car) and only a few ounces of R12 is added every 3 or 4 years?

Thanks,

John

The oil is miscible in the refrigerant, so the system is slowly losing oil while it loses the refrigerant. Over time you'll need to replenish some oil too, but I can't say how much.

[Gawernator]

Originally Posted by uvachief

You must have the only Denso a/c compressor on the planet that didn't fail and leak.

My thoughts exactly. I really can't believe a 29 year old A/C that sat for quite a bit had no leaks or broken components

The technician I worked with added 4-5 oz of oil.

[John_AZ]

Originally Posted by AaronM

The oil is miscible in the refrigerant, so the system is slowly losing oil while it loses the refrigerant. Over time you'll need to replenish some oil too, but I can't say how much.

Thanks for the reply AaronM,

I have been searching on AMA Automotive Air Conditioning Parts & Equipment - Compressors Condensers Accumulators Expansion Va. They have a good AC forum with a lot if information.

I found a couple of answers from senior members on the forum who have added oil but nothing conclusive.
Automotive AC Information Forum - ACKITS.COM

John

[kuehl]

Originally Posted by John_AZ

kuehl,
Is it ever necessary to add oil to an R12 system if it is just serviced (no failure-25 YO car) and only a few ounces of R12 is added every 3 or 4 years?
Thanks,
John

Yes. On any system that you have to top off, add or recharge with refrigerant you are losing oil. The more you use it the more you lose it.

Sometimes its obvious: you'll see dirt behind the clutch pulley, at a compressor case seam, on the compressor to condenser hose ferrules; very common leak points. Hence, a good idea to clean these areas and keep an eye on them.

If you have a leak, and you know you or the previous owner are topping off or adding refrigerant to the system, you are losing oil. Oil does wash off a bit and does evaporate, but 9 times out of 10 it leaves a witness.

If you refer to official Tech Bulletin: group 8, PI 8717, Num 9501, the amount of oil needed in total for the entire ac system is approximately:
1983-1985/1 944 = 10 ounces (300 ml, cc); nominal
1985/2-1991= 4.5 ounces (130 ml, cc); nominal: side note on this one shop manual suggests only 80 ml nominal (ignore it).

The question that comes up often is how much oil to add when topping or recharging.
(By the way, all the oil does not get sucked out of the system when refrigerant is recovered or a vacuum is pulled down, just an ounce or so depending upon the amount near the service ports.)
Very hard to determine without repair history orders.

So, a good rule of thumb, we have found that has worked well over the past 15 or so years is as follows:
Topping off: 2 ounces.
Recharging completely: 4 ounces.
Converting a system from R12 to R134a, and or replacing a compressor and drier: for a 83-85/1 = 8 ounces
and a 85/2-91 = 6 ounces.

Now you may see the difference suggested here of 6 ounces compared to the factory suggested of 4.5 for later model years. That is because we feel the later compressor 10P15E is more prone to lockup (no steel sleeves or ringed pistons) than the earlier 6E171. And, we have never experienced any oil saturation problems with the evaporator. So you'll do just fine performance wise with these recommendations.

[John_AZ]

Thanks for the detailed reply.

I also saw on your web site the improved condenser for the R134a conversions.
Porsche 944 air conditioning parts, Behr, Bosch, Nippondenso, Kuehl, Seltec, Sanden, seal, convert, conversion, barrier hose, Porsche compressor, Porsche condensor, condenser, receiver drier, evaporator, expansion valve, upgrade, R134a,R12,924,951,96

Looks like a great improvement.

Thanks again,
John

[John_AZ]

Originally Posted by uvachief

You must have the only Denso a/c compressor on the planet that didn't fail and leak.

Doug, I am tempting fate just by replying

Originally Posted by kuehl

Yes. On any system that you have to top off, add or recharge with refrigerant you are losing oil. The more you use it the more you lose it.

Sometimes its obvious: you'll see dirt behind the clutch pulley, at a compressor case seam, on the compressor to condenser hose ferrules; very common leak points. Hence, a good idea to clean these areas and keep an eye on them.

If you have a leak, and you know you or the previous owner are topping off or adding refrigerant to the system, you are losing oil. Oil does wash off a bit and does evaporate, but 9 times out of 10 it leaves a witness.

If you refer to official Tech Bulletin: group 8, PI 8717, Num 9501, the amount of oil needed in total for the entire ac system is approximately:
1983-1985/1 944 = 10 ounces (300 ml, cc); nominal
1985/2-1991= 4.5 ounces (130 ml, cc); nominal: side note on this one shop manual suggests only 80 ml nominal (ignore it).

The question that comes up often is how much oil to add when topping or recharging.
(By the way, all the oil does not get sucked out of the system when refrigerant is recovered or a vacuum is pulled down, just an ounce or so depending upon the amount near the service ports.)
Very hard to determine without repair history orders.

So, a good rule of thumb, we have found that has worked well over the past 15 or so years is as follows:
Topping off: 2 ounces.
Recharging completely: 4 ounces.
Converting a system from R12 to R134a, and or replacing a compressor and drier: for a 83-85/1 = 8 ounces
and a 85/2-91 = 6 ounces.

Now you may see the difference suggested here of 6 ounces compared to the factory suggested of 4.5 for later model years. That is because we feel the later compressor 10P15E is more prone to lockup (no steel sleeves or ringed pistons) than the earlier 6E171. And, we have never experienced any oil saturation problems with the evaporator. So you'll do just fine performance wise with these recommendations.

Griffiths,

After a wait of 12 months, I got a 2oz can of R12 oil charge (608 cert) and installed in March 2013-'88 924S.

R12 system blows cold and seems a little bit quieter.

Thanks again for the information.

J_AZ

[VirginiaF1]

R12 = 49F degrees below ambient temp.
R134 = 42F below ambient.
(assuming full pressurization and working components )

[Gawernator]

I don't even have this car. Lol

[djnolan]

Originally Posted by kuehl

Yes. On any system that you have to top off, add or recharge with refrigerant you are losing oil. The more you use it the more you lose it.

Sometimes its obvious: you'll see dirt behind the clutch pulley, at a compressor case seam, on the compressor to condenser hose ferrules; very common leak points. Hence, a good idea to clean these areas and keep an eye on them.

If you have a leak, and you know you or the previous owner are topping off or adding refrigerant to the system, you are losing oil. Oil does wash off a bit and does evaporate, but 9 times out of 10 it leaves a witness.

If you refer to official Tech Bulletin: group 8, PI 8717, Num 9501, the amount of oil needed in total for the entire ac system is approximately:
1983-1985/1 944 = 10 ounces (300 ml, cc); nominal
1985/2-1991= 4.5 ounces (130 ml, cc); nominal: side note on this one shop manual suggests only 80 ml nominal (ignore it).

The question that comes up often is how much oil to add when topping or recharging.
(By the way, all the oil does not get sucked out of the system when refrigerant is recovered or a vacuum is pulled down, just an ounce or so depending upon the amount near the service ports.)
Very hard to determine without repair history orders.

So, a good rule of thumb, we have found that has worked well over the past 15 or so years is as follows:
Topping off: 2 ounces.
Recharging completely: 4 ounces.
Converting a system from R12 to R134a, and or replacing a compressor and drier: for a 83-85/1 = 8 ounces
and a 85/2-91 = 6 ounces.

Now you may see the difference suggested here of 6 ounces compared to the factory suggested of 4.5 for later model years. That is because we feel the later compressor 10P15E is more prone to lockup (no steel sleeves or ringed pistons) than the earlier 6E171. And, we have never experienced any oil saturation problems with the evaporator. So you'll do just fine performance wise with these recommendations.

Quick question: If the system has never been flushed, what type of oil should I be adding? PAG or Esther? Is there any harm in adding a few ounces of BG Frigi-Quiet? I bought a bottle and an oil injector.

By the way this thread gets 5-star rating. How does one rate a thread?

[kuehl]

Originally Posted by djnolan

Quick question: If the system has never been flushed, what type of oil should I be adding? PAG or Esther? Is there any harm in adding a few ounces of BG Frigi-Quiet? I bought a bottle and an oil injector.

By the way this thread gets 5-star rating. How does one rate a thread?

In our experience, if the system was R12 and only used 'mineral oil' (typical of R12)
and you are converting to R134a.... then use ESTER.

I sense BG's Frigi is a Di-capped PAG. We never used it or any other double end cap oils. Simply because we never saw the need.
I'm not going to recommend it or not recommended it simply because we don't have enough data on using it.

In the past 18 or more years of doing 911/912/924/944/928/930/964 R12 to R134a conversions we have always marketed
ESTER and never had any issues.

And, we suggest you avoid any product that has a sealant, enhancer or other additive.