PAG oil grade

[cellaway]

Does any one know what viscosity of PAG oil our aircon uses ? PAG 46 and 100 seem to be the most common but 150 was used by some GM cars between the 90’s to the 2000’s and is still required by some compressors. I’m guessing the the higher the number the higher the viscosity

[Tuga2112]

i dont know the answer to your guestion. but to note on your own statement.

the elan was developed in the late 80s. i would be surprised if it used a lubricant that was more predominant in the late 90s and 2000's.

I i would also be surprised if the available documentation online has nothing on that topic ? it seems like the kind of information that would be put togehter wit the engine oil details in the workshop manual

[dapinky]

I have a car with (non-functioning) AC, so have no idea!

What I would say is that the original system used R12 gas, but that can no longer be used, so many have been adapted to use R134a. Now, I know certain parts need changing to suit, but I also think that the oil used with R12 *may* be different from that required for R123a?????????

Is the original compressor retained? I just don't know.

[cellaway]

Hey Dave
From a previous post from Simon P, he mentioned that R12 used a mineral oil and R134a was a PAG synthetic oil. I haven't been able to find anything referencing which viscosity of PAG to use so was going for the 46 as it's the most commonly used The higher the number the higher the viscosity, so guess it will either work or not
Chriso

[cellaway]

Again from previous posts. You need to change adaptors, receiver drier and the tri switch, There's not a great deal more in the system apart from the condenser, controls and blower motor.

[cellaway]

And the compressor

[dapinky]

My system was (so I was told by the previous owner) converted a few years ago to R134a, and a different compressor etc was fitted.

The system still had some pressure in it when I got it, but the gas canister /filler I have doesn't connect to it, so I have no idea what the system is, if it's a hybrid, or what gas it uses (the valve appears to be a Schrader valve thing, so appears to be R12??????

To be honest, in my 45 years of driving, I have had many cars with AC fitted - but only had it working in 2 of them (one was brand new, and it worked for 3 years, the other was the Landrover that I drove to Gambia in January and gave away) - so I don't really miss it. Especially in the UK where it doesn't get hot enough to need to keep the roof up, and it lives in the garage for the Winter.

I may worry about it at some time in the future, or I may not.

[cellaway]

The Lotus fitted Sandan SD compressor takes PAG 46 oil. I'm not sure which compressor we use on the M100

[cellaway]

The Lotus fitted Sandan SD compressor takes PAG 46 oil. I don't know which compressor we use on the M100

[Simon_P]

PAG100 was recommended to me.

R12 oil is mineral base so not compatible with PAG. There may be one type suits all available now. Drain the old stuff out.

Change the receiver drier - it is a service part.
Change as many O rings as you can the black R12 ones will leak with 134a don't worry about the ones you can't get to. Service port adapters are cheap and available.
No need to change anything else as it will all work .

You should also have a sticker to show it is filled with 134a (that's a legal bit)

The manual is quite good - 134a should have a different fill quantity but I can't remember what it is.

[cellaway]

Thanks Simon, I was going to measure the amount of oil taken out and put the same amount in. I think the pressure is higher with R 134a so that’s probably why ideally you would change the tri switch and compressor.

Chriso

[cellaway]

Is there a designated outlet to drain the old compressor oil or is it a case of placing a tray underneath and opening up all the unions.

[Simon_P]

Yes, on the back end of the Zexel compressor there's a drain plug.