Hi all, does anyone know which one is the LP side of the AC connector/valve?

Is it the one close to the fire wall?

 

The smaller of the two is the LP

 

On our '93 the LP port is on the A/C line between the power steering fluid reservoir and the group of relays on the firewall, very easy to access.

 

Thanks!!!
However I can't see any significant difference between the two... I have the older type (R12)? So, I'll need an adapter. The caps are identical. Though, if anything and if I remember right, one of them is slightly higher.
The tube on the connector near the fire wall is slightly larger and that's why I assumed it's the LP side.

 

I just watched a clip on youtube which says that I need to replace the evaporator to one that is bigger and that I need to add new oil in the system...

Is that really necessary???

 

Not sure why they would say to go to a larger evaporator-doesn't make much sense since the evap core is housed in the dash in the heater/AC case so you certainly can't change the size of either the AC or the heater core.If you are changing to r134 then yes you will add new oil with the Freon once the system has been evacuated and is ready for the r134.But other than the Freon and oil you shouldn't need to replace anything else unless you find a leak somewhere in the system which may need to be resealed. Cary

 

Hi Roland,

It's been awhile since I've read a discussion about converting an R12 car to R134a, but I am certain that other XJ40 owners have done so without having to change their evaporators. However, I do recall a lot of discussion about replacing the receiver-dryer, and possibly the expansion valve.

You do want to have any remaining R12 evacuated and the old mineral oil drained. You do need to use the correct amount of new R134a-compatible oil, and before charging with R134a you want to evacuate the system under vacuum for at least 45 minutes.

Note that the term "Freon" is often used generically to describe any refrigerant, but technically it's a registered trade name that DuPont used for the family of refrigerants that included R12, but it is not used to describe R134a, which is simply called "refrigerant."

Note also that R134a will probably result in air from your vents that is a few degrees warmer than it was using R12....

Cheers,

Don

 

Thanks guys!!!

Am I right, assuming I'll have to borrow/hire a vacuum pump to clean out any residual oil/refrigerant before adding new oil and refrigerant... OR if the system is empty already, maybe just add a can of refrigerant and oil... perhaps in that order...

Someone just told me, that if the system hasn't been "broken", I don't have to vacuum or add oil... If that's the case and the info is correct, I should be good to go, just recharge the system, using the kit I bought... :-) Or... !?

 

The vacuum pump will only remove the old refrigerant and moisture in the system.

It WILL NOT remove the oil from the compressor. You will have to drain that oil out and replace it with R134A compatible oil. You should also change the receiver/dryer. I'm unsure about the expansion valve as my car is a factory R134A model and I didn't have to do any of the above to get the a/c running.

As Don says, there are lots of threads in the archive on converting from R12 but one thing is for sure - the oil you have in there MUST be replaced or the system WILL break down.

Good luck

Larry

 

Just in from the garage and having recharged the system with one can of refrigerant, getting 35 psi and cold air coming from the vents...

I also called the company that sold the "Duracool" kit and asked if it's necessary to change the oil but he adamantly said that the notion of having to change the oil is outdated and that the O-rings will work just fine with the oil present...

I my self know absolutely nothing in this matter, so I'm a bit lost here...

 

Ah - I see. Your technician is right. The oil will be fine using Duracool and your system will work, so no worries!

The reason you wouldn't have to change the oil is because the R134A didn't get installed in your system.

Duracool isn't R134A, it's basically a mixture of propane and butane so it won't affect the oil.

I was under the impression you were going to convert to R134A - sorry!

 

Butane/Propane mix...

Now I'm REALLY surprised!!! Butane/Propane mix!?

You mean, the same thing as those camping cans, costing 5$ ???

 

yep!

It's a excellent refrigerant though, molecules are considerably larger than R134A so will leak out MUCH more slowly and will cool better ...but yes, good old propane is what you have in there.

Sold under the name of Red-Tek in Canada, a lot of people use it, so need for concern!

cheers

Larry

 

ALRIGHT!!!

Do they even have the same thread and would they even be interchangeable???

 

This is what I found out from the camping cans, sold here in Sweden... Thread 7/16.


Butane (content ≥ 0,1%
butadien (203-450-8))
CAS-no. 106-97-8
EG-no. 203-448-7
Indexnumber 601-004-00-0
F+, R12,
H220, H280, Flam. Gas 1, Press.
Gas (*),
45%

Propane CAS-nr 74-98-6
EG-no. 200-827-9
Index number 601-003-00-5
F+, R12,R18,
H220, H280, Flam. Gas 1, Press.
Gas (*),
26%

Isobutane CAS-nr 75-28-5
EG-nr 200-857-2
Indexnumber 601-004-00-0
F+, R12,
H220, H280, Flam. Gas 1, Press.
Gas (*)
28%

 

I just gave you a brief rundown of the constituents etc, I certainly don't recommend tapping into your camping and barbecue propane tanks to fill the a/c system unless you are on the moon or something and can't get anything else!!

Stick with the Duracool or equivalent once you've started down that road!!

 

This is probably the best manual on A/C out there, was my A/C bible when I rebuilt my system.

http://ecat.spectrapremium.com/bulletins/download/automotive_techtip_eng_2007.pdf

all the best

Larry

 

Don't worry, I don't intend to. I bought 4 cans of Duracool :-) ...

I was only curious if it's a case of, same s**t different name, syndrom...

 

The link to the old A/C manual now appears dead, here is another source for what I consider the ultimate guide to A/C work - the "Bible"

https://web.archive.org/web/20151123...p_eng_2007.pdf

cheers lads (with thanks to Nick!)

Larry