Checking oil level in A/C compressor.

[Jakter]

I have a 1967 Chrysler Newport Custom that I want to check the oil level in the A/C compressor before I try to see if the A/C works.
I have the FSM and read and made up the dipstick for checking the oil, I know where the two spots are to check from on the compressor but the dimensions they give for 6oz. or 8oz. ,min. and max., I don't understand where to measure from.
The instruction for making the dipstick say to grind off the threads on one side of the brass fitting.
Is that so the fitting fits into the hole the plug screws into?
Do I measure from essentially the body off the compressor, down the dipstick, to the highest oil level on the dipstick?
Looking at the dimensions it's giving I'm not really sure where to measure from and to.

Thanks.

 

[Davea Lux]

I have a 1967 Chrysler Newport Custom that I want to check the oil level in the A/C compressor before I try to see if the A/C works.
I have the FSM and read and made up the dipstick for checking the oil, I know where the two spots are to check from on the compressor but the dimensions they give for 6oz. or 8oz. ,min. and max., I don't understand where to measure from.
The instruction for making the dipstick say to grind off the threads on one side of the brass fitting.
Is that so the fitting fits into the hole the plug screws into?
Do I measure from essentially the body off the compressor, down the dipstick, to the highest oil level on the dipstick?
Looking at the dimensions it's giving I'm not really sure where to measure from and to.

Thanks.

If you look on the passenger side of the compressor body there is a hex threaded fitting about halfway up the compressor body. The system needs to be discharged BEFORE the plug is removed. Do you know what refrigerant is in the system now? If it is R-12, you should probably have a competent service facility discharge the system. You remove the hex plug and insert a 1/8' rod in the hole until it stops as the bottom of the compressor. Remove the rod and see how far up the rod there is oil. There is a chart that gives the amount of oil per a specific depth of oil on the dipstick in the FSM. Note this measurement was designed for systems that were operating. If the system was low on refrigerant and run that way, most of the oil is likely in the filter dryer, condenser and evaporator, which makes the dipstick method of checking oil very inaccurate. That is why a service facility removes all of the oil and refrigerant prior to recharging the system. That way the proper amount of oil can be added without worry of putting too much or too little oil in the system. If the system has R-12 in it now, the system must be upgraded before recharging with R-134a. RV2 compressors have a high failure rate running R-134a and the oil in a R-12 system will turn to snot if exposed to R-134a.

Dave

 

[Jakter]

The FSM shows two dipsticks, one for use in the crankcase and one for use in the sump, both different lengths. I thought I could check it from the sump (driver side) because of easier access. The length on the sump dipstick is 2.25" + .375" for the fitting. The min./max. oil level shows 2.875 to 3.50. I didn't know how I was supposed to measure, say 2 7/8 " on a dipstick that was 2 1/4" long.
I plan to keep it R-12.
I guess you can't measure from the sump but don't understand why they show a sump dipstick.
Thank.

 

[Davea Lux]

The FSM shows two dipsticks, one for use in the crankcase and one for use in the sump, both different lengths. I thought I could check it from the sump (driver side) because of easier access. The length on the sump dipstick is 2.25" + .375" for the fitting. The min./max. oil level shows 2.875 to 3.50. I didn't know how I was supposed to measure, say 2 7/8 " on a dipstick that was 2 1/4" long.
I plan to keep it R-12.
I guess you can't measure from the sump but don't understand why they show a sump dipstick.
Thank.

On a system that was operating, the charge could be brought down to about 1 psi, that was enough charge to to keep air from getting into the system if the measurement was done quickly. At any given time on an operating system about 1/3 to 1/2 of the oil would be out of the sump so some guesstimating would be done and oil add as thought necessary. We used to figure on adding about 2oz of oil on a system recharge if it was just low on gas. If a line had broken or some other full discharge event had occurred, the filter dryer would be replaced and the system would be purged and fully recharged with oil and refrigerant. In the old days when dinosaurs ruled the Earth, R-12 was about .35lb so most of the time it would just be vented out of the system. Most of us that worked on these systems a lot probably have a sky hole someplace.

Dave

 

[CBODY67]

I believe that somewhere in the FSM, it mentions that the "sump oil" should only be measured on a discharged system when the compressor is rebuilt or replaced. NOT as a matter of course, as you might check the atf or motor oil level. Different installations can have different oil sumps on the RV-2 compressors, so getting the specs applicable to your vehicle can be important.

I believe there as some acceptable "drop-in" R-12 replacements? One which is kind of a hybrid gas between R-12 and R-134a, I believe. But finding a good source for quality R-12 might be an issue.

Just some thoughts,
CBODY67