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R12 oil

Scratch on Tue May 07, 2013 12:35 PM User is offline

Year: 1979
Make: Ford
Model: Granada
Engine Size: 250
Refrigerant Type: R12
Ambient Temp: na
Pressure Low: na
Pressure High: na
Country of Origin: United States

I bought all the Mastercool tools needed to replace the shaft components and am now ready to charge in some R12. I only have 4 ounces left of Sercon oil left and I need to buy more oil. Does anyone know what oil I can buy for R12? I believe the correct oil is mineral oil, not ester or PAG. There are O'Reilly, Autozone, and Napa stores near my house.

Thank you

scott johnson

Edited: Tue June 25, 2013 at 11:17 PM by Scratch

Cussboy on Tue May 07, 2013 9:10 PM User is offline

525 refrigeration oil; some call this "mineral oil". Of those stores: maybe NAPA can order it, doubt the others. Did you try this board's sponsor, AMA Auto Air, click the link on this Forum page in the upper right.

NickD on Wed May 08, 2013 8:17 AM User is offline

Did you try your Ford dealer? Best to call, when that phones rings, the heck with you standing there with a handful of cash, phone always comes first. If not in stock maybe they can order it. Only need a cup, may be a couple of bucks more, but not like you have to change it every 3,000 miles.

mk378 on Wed May 08, 2013 11:04 AM User is offline

NAPA may still have it. The others, no. Nick's suggestion to buy it from a dealer is also good but you will need to know what to ask for since the car makers usually have their own numbers for what is basically a generic oil.

Scratch on Wed May 08, 2013 11:33 AM User is offline

Thanks for the replies. I really appreciate the help I get from the A/C professionals on this board. I called Napa and they told me their mineral oil for R12 is #TEM 209500. The oil is in stock and I will go pick it up today.

Also, I wanted to mention that after buying all the Mastercool tools I needed to remove and replace the shaft seals, I came to a complete stop when I found the 90415 tool would not reach the steel cage/inner seal assembly. Evidently Mastercool is now selling a shorter, different 90415 tool. I called several tool suppliers and one salesman told me I needed a Kent Moore seal removal tool and I was able to find the exact tool on Ebay. The wrong tool cost me a two week delay in getting the compressor ready for recharging.

Thanks again

scott johnson

Edited: Wed May 08, 2013 at 12:08 PM by Scratch

WyrTwister on Sun May 12, 2013 9:37 AM User is offlineView users profile

Bingo ! You are correct . I bought a quart of mineral oil at NAPA for about $ 10 .

God bless

Scratch on Mon June 10, 2013 8:12 PM User is offline

After buying the mineral oil, I poured 8 ounces right into the high pressure hose. I then drove the car with the A/C on to circulate the oil.

Today I tried to charge in the R12 but only a few ounces went in. The low side reads 45 psi but the high side reads zero. I don't know if the few ounces were sucked in or just went in to equalize the pressure of the tank.

I'm beginning to suspect a bad expansion valve or the compressor failed. I only removed the compressor to replace the shaft seals. It worked until the hose nut loosened and the refrigerant leaked out.

Any ideas would be greatly appreciated.

Thank you

scott johnson

mk378 on Mon June 10, 2013 8:57 PM User is offline

Hold on. If it's an A6 compressor, you need to put the oil into the compressor crankcase by opening the oil plug on the side. The square York compressor also has a crankcase and oil plug (it's the same crank / piston mechanism as a lawn mower engine). In any A/C system, the oil only circulates because there's refrigerant to push it around. Thus running the compressor on an empty system is very bad for it. Second, did you evacuate before charging? Third, reading less on the high side than is on the low side almost certainly means that the high side gauge hose isn't properly coupled to the car. If you have isolation valves on the fittings between the compressor and the car hoses, make sure they are open. To evacuate / charge a system with the service ports on the isolation valves, open the isolation valves halfway.

Edited: Mon June 10, 2013 at 9:07 PM by mk378

Scratch on Mon June 10, 2013 9:52 PM User is offline

Thank you mk378. You have always been helpful to myself and all the other posters requesting help. I have always put in the oil through the hose. I did evacuate the system for 30 minutes before trying to charge in the R12. The reason I see zero pressure on the high side I attributed to the compressor not compressing what little refrigerant is in the system.

I did drive around with the compressor on and I think I destroyed it. If this is the case, my carelessness and stupidity will cost me at least $200 to buy a replacement.

Thanks again

scott johnson

mk378 on Mon June 10, 2013 9:57 PM User is offline

Even a bad compressor will let pressure through the check valves from the low side to the high side. I really suspect the car has isolation valves and your attempt to evacuate and charge didn't do anything because they weren't open.

Scratch on Tue June 25, 2013 5:22 PM User is offline

Well I found out why the R12 wasn't being sucked into the compressor. Last year I replaced the three depressors on my manifold gauge hoses. I screwed the depressor for the low side hose too far down and it wasn't making contact with the valve. I now realize that I wasn't pulling a vacuum on the a/c system so I performed a leak test and the vacuum held for hours. I next evacuated for 30 minutes. I then drove to the parking lot of a supermarket and charged in 8 ozs of R12. I immediately saw pressure on the low side and high side as well as frost completely covering the throttle suction valve. The a/c only cools to 60 degrees and climbs up to 80 degrees. As soon as I got home I connected the gauge to the high side and saw 65 psi. A week later the gauge still shows 65 psi so I believe the system is once again gas tight and I will charge in 3 lbs 8 ozs and hope to see 40 degrees.

scott johnson

Cussboy on Tue June 25, 2013 6:41 PM User is offline

Originally posted by: Scratch
I then drove to the parking lot of a supermarket and charged in 8 ozs of R12.

I need to ask: why did you do this in a supermarket parking lot?

Scratch on Tue June 25, 2013 8:05 PM User is offline

We were going shopping anyway and I prefer to charge in the refrigerant in a parking lot. There's a lot of empty spaces and I don't have to breathe exhaust fumes. The people walking by see the 30lb cannister sitting on a folding chair but might not know what I'm doing. From start to finish took less than 10 minutes.

scott johnson

pippo on Tue June 25, 2013 8:36 PM User is offline

Its done, but for the record, if you cant find mineral oil easily, I understand ester will do just fine. Easily gotten. Compatable with almost any refrigerant, I understand. Im not an expert- just always trying to learn ametuer.......if im wrong, members pls advise......

beware of the arrival

wptski on Tue June 25, 2013 11:00 PM User is offline

I've got a quart of GM brand from way back.

Scratch on Tue August 27, 2013 4:57 PM User is offline

Hello air conditioning pros,

The last time I posted back in June I charged in 8 ozs of R12 just to check for leaks. I previously replaced the shaft seals, pressure tested the compressor out of the car with nitrogen, pressure tested the entire system with nitrogen, pulled a vacuum for 1 hr with my Robinaire vacuum pump, and finally I left the system with 29 inches overnight. The next morning the gauge still read 29 inches so I was confident the system was gas tight.

After charging in the 8 ozs of R12, I left the car in the garage for several weeks while I drove my 2008 Chevrolet. I checked the high pressure gauge every day and it never moved from 65 psi. I only have about 4 1/2 lbs of R12 left so I wanted to make absolutely sure there were no leaks. Last Friday I once again drove to the supermarket parking lot. I placed the R12 cannister on the digital gauge and slowly charged in another 8 ozs of refrigerant. The low side gauge showed pressure and so did the high side. I saw the expansion valve get wet and the throttle suction valve covered in frost. I got in the car and checked the round temperature gauge and saw no change. The car now had 16 ozs of a required 64 ozs so I charged in 8 ozs more. I revved the engine up and down but still no cooling. I charged in another 8 ozs for a total of 32 ozs with the same results. I decided to go ahead and charge in 16 ozs and the system now had 48 ozs/3 lbs. I got in the car and again revved the engine up and down and this time I saw the gauge go down to 55 degrees with cold air coming out of the vents. I thought I succeeded in once again having a/c in this car so I turned off the ignition and removed the gauges. I know the system wants a total of 64 ozs but I wanted to see how the a/c worked before charging in my last 1 1/2 lbs of R12.

I went into the supermarket to buy some groceries and when I turned on the a/c there was no cooling. The temperature gauge read ambient vent temperature of 70 degrees. I drove home with no cooling and
when I got into the garage I turned off the engine, popped the hood, and turned the engine on. The a/c cooled to 55 degrees again.

This morning, Tuesday, I went out and the a/c cooled to 55 degrees for several minutes and then no cooling at all. I connected the gauges and at idle the low side read 34 psi and the high side read 99 psi. I checked the readings at 1500 rpm and the gauges did not change at all. The expansion valve is covered with what looks like a thin layer of ice and the throttle suction valve is completely covered in frost.

I'm beginning to suspect a bad expansion valve and if this is the case I will have to pay a shop $35 to remove 3 lbs of R12 in order to install a new one. Any ideas would be appreciated.

Thank you,


scott johnson

mk378 on Tue August 27, 2013 10:32 PM User is offline

The saying goes, you get all your cooling from the last oz of refrigerant. Don't run undercharged.

Scratch on Wed August 28, 2013 11:32 AM User is offline


I am always grateful for your input. I'll go ahead and charge in 1 lb of R12 which should bring my total charge to 4 lbs. I have always charged in the required amount of refrigerant needed. What I was hoping to see with only 3lbs of R12 was continuous cooling when I turned on the A/C. I thought that 3 lbs would be enough for continuous cooling. I didn't expect to see 40 degrees but I thought I would get 60 degrees.

I'm guessing 3 lbs of R12 isn't enough to produce the pressure needed to open the expansion valve and allow liquid refrigerant into the evaporator. With the expansion valve closed, the low and high side pressures won't change with RPM.

If I get the exact results after adding the additional freon, could I then suspect a faulty expansion valve?

Thank you,


scott johnson

Scratch on Thu August 14, 2014 10:40 PM User is offline

After working on the a/c on this 1979 Ford Granada for the past three years, I finally have a working a/c. Last year, I did charge in the last pound of R12, but two weeks later all of the refrigerant was gone. I waited until this year to make a final attempt to get cold air in the passenger compartment.

I was going to sell my 1978 Ford Granada to the state so I brought it to an a/c shop to have all the refrigerant removed. When I got home, I removed the condenser, compressor, low and high pressure hoses, and expansion valve/suction throttle valve assembly. This was all done on a Thursday. The following Thursday (my street cleaning day when I have to move the car) I removed all of the corresponding components except the TVX and STV from the 1979 Ford Granada. I installed the 1978 compressor, condenser, and hoses onto the 1979 Granada,adding 8 ounces of oil. The next Thursday I connected the Robinaire vacuum pump and pulled a vacuum for half an hour. I closed the wheel and checked the vacuum gauge six hours later. The needle didn't move from 29 inches. I repeated this over the next two Thursdays. On the fourth Thursday, I also pressure tested the system with nitrogen gas. This test was only one hour in duration.

I bought five twelve ounce cans of R12 from Craigslist for $75. On June 12th I drove to the supermarket parking lot and tried to charge in the refrigerant. The can was still full after several minutes so I closed the gauge wheel and drove home. I now knew that the TVX from the 1979 Granada was bad. I removed it and installed the 1978 TVX/STV assembly. The following Thursday, June 19th, I connected the vacuum pump and again pulled a vacuum for half an hour before closing the wheel. When the vacuum held 29 inches after six hours, I drove back to the supermarket parking lot and this time the R12 went right in. I got approximately 15 psi on the low side and approximately 90 psi on the high side. The Cooper temperature gauge in the middle vent didn't move from 80 degrees. I did see a thin film of moisture on the TVX/STV block. The air coming out of the vent didn't feel dry or hot. I now had approximately twelve ounces of R12 charged in. On June 26th, I charged in another twelve ounces and the low side went to about 20 psi and the high side was about 100 psi. The TVX/STV was again moist and the Cooper temperature gauge didn't move. I charged in the third can on July 3rd and now the Cooper temperature gauge moved from about 80 degrees to 50 degrees. The low side was about 35 psi and the high side about 140 psi. Frost completely covered the TVX/STV assembly. As I drove home in a cold passenger compartment, I saw 40 degrees on the temperature gauge.

Now these a/c components blew 20 degrees back in 2000. I only had about thirty six ounces of R12 in the system and wasn't sure if I should add anymore. However, the next week I decided to add twelve more ounces. I now get 35 degrees at the middle vent with 40 psi on the low side and 140 psi on the high. With only thirty six ounces of R12 I got 40 degrees. I'm guessing that the TVX that I bought brand new from Kragens back in 2000 was always defective but I'm not complaining.

This will be the last time I work on my car's a/c after my first attempt back in 1980. I would like to thank everyone here who have answered my queries.


scott johnson

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