A/C Question

[Bonnewagon]

Mac442- THANKS!!! That is what I wanted to see. As for the R-12 equivalent I am using Enviro-Safe R134/R12 replacement. Here is what has changed since I first did this. At the time it was OK to sell R-12 replacement freons. Thus you had a plethora of brands (Freeze12, etc) vying for that market. The stuff Enviro-Safe sold was just another replacement and mixed fine with the original mineral oil in R-12 systems. Next time I ordered I noticed it only said R134a replacement. Huh? Then when I got my 609 certification I saw that R-12 equivalents were banned. But, it was the same stuff, right? Right. Same part number- just different text on can. It is a hydrocarbon based refrigerant and while flammable, works great in either system. But they can't legally SAY it works in R-12 systems. So- I used it and am glad I did. I left the oil alone and only changed the compressor and accumulator. Here is the site https://www.es-refrigerants.com/pro...rial-r134a-replacement-cans-cases/details.asp and here is the R-12 disclaimer https://www.es-refrigerants.com/resources/faq/w/id/76/refid/461/details.asp .

 

[partsbox]

Mac442- THANKS!!! That is what I wanted to see. As for the R-12 equivalent I am using Enviro-Safe R134/R12 replacement. Here is what has changed since I first did this. At the time it was OK to sell R-12 replacement freons. Thus you had a plethora of brands (Freeze12, etc) vying for that market. The stuff Enviro-Safe sold was just another replacement and mixed fine with the original mineral oil in R-12 systems. Next time I ordered I noticed it only said R134a replacement. Huh? Then when I got my 609 certification I saw that R-12 equivalents were banned. But, it was the same stuff, right? Right. Same part number- just different text on can. It is a hydrocarbon based refrigerant and while flammable, works great in either system. But they can't legally SAY it works in R-12 systems. So- I used it and am glad I did. I left the oil alone and only changed the compressor and accumulator. Here is the site https://www.es-refrigerants.com/pro...rial-r134a-replacement-cans-cases/details.asp and here is the R-12 disclaimer https://www.es-refrigerants.com/resources/faq/w/id/76/refid/461/details.asp .

Bonnewagon - Thank you, this is great info and much appriciated. Do you happen to know if their ProSeal sealant is compatible as well?

 

[Bonnewagon]

I don't know I never tried it. But with all the problems I'm having with the Jeep I am willing to try anything. The ClipLight worked for me in the past but this damn Jeep is giving me fits. The ClipLight says when it gets to the leak the pressure drop creates moisture and that causes it to harden. The Pro-Seal description said it makes a hard seal all over everything. I'm not sure if that is desirable. And of course the usual sealers just cause the seals to swell.

 

[airboatgreg]

Don't mess with the switch. You can tell when you have enough refrigerant in the system when the inlet and outlet of the evaporator are at the same temperature, Engine on fast idle, fan on high while keeping an eye on the head pressures. Huge mistake people make is not having a vacuum pump that works. Including shops. Just because the gauge says it is 30" of vacuum does not mean it is. The point of a vacuum pump is to BOIL the moisture out of the system. I taught this stuff for years and checked a lot of vacuum pumps using a jar with an AC fitting brazed in the cap with a half inch of water and at couple drops of refrigerant oil. If your pump is working the water will boil. I never saw an air operated one boil water. Also, where do you think the moisture is held after it boils? In the vacuum pump oil. So when was the last time you changed that? Make sure your fan clutch is working. Please tell me you didn't put a used accumulator on it. That has desiccant which absorbs moisture and is the oil reservoir for the system. Pretty important piece. So another question is how much oil??? The next one to politely raise their hand gets the answer

 

[Turbo Zach]

Don't mess with the switch. You can tell when you have enough refrigerant in the system when the inlet and outlet of the evaporator are at the same temperature, Engine on fast idle, fan on high while keeping an eye on the head pressures. Huge mistake people make is not having a vacuum pump that works. Including shops. Just because the gauge says it is 30" of vacuum does not mean it is. The point of a vacuum pump is to BOIL the moisture out of the system. I taught this stuff for years and checked a lot of vacuum pumps using a jar with an AC fitting brazed in the cap with a half inch of water and at couple drops of refrigerant oil. If your pump is working the water will boil. I never saw an air operated one boil water. Also, where do you think the moisture is held after it boils? In the vacuum pump oil. So when was the last time you changed that? Make sure your fan clutch is working. Please tell me you didn't put a used accumulator on it. That has desiccant which absorbs moisture and is the oil reservoir for the system. Pretty important piece. So another question is how much oil??? The next one to politely raise their hand gets the answer

I replaced the drier, compressor, and orfice tube when I changed mine over. Also replaced the compressor lines because I had too. Flushed the condenser and evaporator the best I could. I don't have an oil injector so I use the pre charged cans. I only put oil in if I replace a compressor. I think they are 4oz cans. I have been using a air vacuum pump for years. I didn't know that was not necessarily good enough? Fixed A/C on four machines last week. On my car it was 90° out side and very humid. Going down the highway the air coming out of vents was 35-38°. So I call that a win.

 

[Bonnewagon]

how much oil???

Well by me I go by the FSM and use what they say each individual component needs. I figure too much is better than too little as it will pool at several locations anyway. Complete system replacement gets the whole amount spec'd of course. I have a venturi pump and it was OK but took FOREVER to get the vacuum down. So I bought a very good pump and never looked back. I use Black Gold oil.

 

[airboatgreg]

Well by me I go by the FSM and use what they say each individual component needs. I figure too much is better than too little as it will pool at several locations anyway. Complete system replacement gets the whole amount spec'd of course. I have a venturi pump and it was OK but took FOREVER to get the vacuum down. So I bought a very good pump and never looked back. I use Black Gold oil.

If you are starting out with a new system or have done a really good job flushing the GBodys take 10 TOTAL ounces. 2 in the condenser, 3 in evap and 5 in accumulator. Make sure you drain the compressor. Cannot beat a good vacuum pump. I fixed many vans with dual systems just by evacuating overnight and measuring the amount of freon to put in.

 

[Bonnewagon]

I should also mention that measuring the charge is critical. R134a especially wants the EXACT amount on the decal or what the FSM says. I found an inexpensive digital Postal Scale on Fleabay for around $20. It is good to two decimal points. I found it only takes a few ounces to enable the compressor. Adding freon until your output temps are as cold as they can be is a waste of freon and potentially damaging to the system.

 

[69hurstolds]

Your system is considered operating normally if on average, your duct temps are between 36-42 degrees F (with R12, and if outside air temps are <100 degrees F) per GM technical information.

I'm not sure about other G-bodies, but a 1987 Olds Cutlass 442 requires 6 ounces (0.17 kg) as is listed as the amount of oil to use in the system. I guess you could use more, but you may be just wasting it. Not sure how much is too much. Remember the oil is miscible with R12 and it gets carried along with the R12. It may just pool there or it may build up somewhere and potentially cause problems. I doubt if you added 6.1 oz. to the system it doesn't hurt it. But the oil isn't what's flashing to cool you down. You put too many oil droplets in the way and you could hinder A/C performance at some point above 6 oz.

You can find this information in at least 2 places. If you still have the original compressor on your car, you can simply look at the label to find out you require 6 oz. of R12 oil, and if you look at the sticker on the evap housing, you'd find 3.25 lbs. as the amount of R12 refrigerant in the system. (B-body uses a bit more, at 3.50 lbs.)

Also, you can find the oil amount per the 1987 Cutlass CSM, R-4 systems distribute that 6 oz of oil as follows:

On page 1B-20-
For full system flush and/or all new system components, you add 3 oz. oil in the compressor, and 3 oz. oil to the accumulator.

On page 1B-18-
New oil must be added to the system when single components are replaced (these are not cumulative, only if the individual component gets replaced)-
- Compressor- drain old compressor oil and measure amount. If < 3 oz. of oil drained, add 3 oz. of new oil. It is stressed in the CSM that a new compressor must have at least 3 oz. of oil when installed.
- Evaporator- 3 oz.
- Condenser- 1 oz.
- Accumulator- drain oil out of old accumulator and measure amount. Add new oil in that amount PLUS 2 oz. If no old oil can be drained, add back 2 oz. of new oil.

 

[Bonnewagon]

Another question: Why do some AC systems cycle constantly and others don't? My 1983 Bonnewagon has a 1979 Pontiac 301 but I kept the whole original stock 231 AC system intact. The Turbo 301 used the same mounting brackets for the radial compressor that came on the stock 231 so I sourced those and re-used the stock compressor. I yanked all OBD1 CCC stuff so when I turn the AC on the only control is the low pressure switch. And if there is enough pressure in the system to enable the compressor it will run constantly. Meanwhile on my 2000 Jeep Cherokee w/OBD2 the compressor cycles all the time. Some times less, sometimes more. But it never runs constantly. What are the parameters that govern this? Ambient temperature? Humidity? High/Low pressures? On both vehicles I am getting 35° below ambient so I am not complaining. But the cycling worries me. The FSM says up to 10 cycles per minute is acceptable. Really?