AC Question (1 Viewer)

[offroadvegan]

A shop is willing to hook me up with a $60 fill of R134a. But I have an R12 system. He claims he can just fill it with 134.

Is this true?

What's the worst that can happen? My system is completely empty.

 

[Rifleman]

The worst that can happen is you'll waste 60 bucks on 134 A, if you don't first find out where all your leaks are that allowed your old R12 to leak out.

 

[offroadvegan]

The system doesn't have any leaks.

 

[bushdoctor]

 

[flintknapper]

The system doesn't have any leaks.

Please explain?

Did you have the system evacuated at some time prior to now?

If not then you do have a 'leak'.

Refrigerants are non-consumables (they are not used up in operation).

Your system can be 'converted' from R12 to R134a but don't expect it to be as efficient. Also, considering the price you were quoted it sounds very much like they intend to cut corners when doing the conversion.

IF you are certain you have no leaks and your system is in otherwise good shape, I would recommend you stay with R12.

 

[Red Merle]

The systems use different fittings. I am not sure how he will fill the system with R134a, but I would find out. You won't be able to do anything on your own in the future unless you do a real conversion.

 

[ZackR]

More details needed... is there an issue with your current AC system?

 

[Cruzerman]

When I did the retrofit myself, I changed the o-rings, flushed out the system, replaced the drier, replaced the expansion valve. All are cheap parts. I personally wouldn't just fill and cross your fingers.

 

[Red Merle]

More details needed... is there an issue with your current AC system?

Probably in-op if it's empty.

My guess is that there is a leak, maybe more than one. I would get some dye in there too if you can.

Seems like there should be a fine or something if dudes are just pumping r134a into R12 systems. I am thinking there was a reason they have different fittings, different pressures, maybe?

It's seems too easy to work, honestly. There has to be a catch.

I will say though that once you start monkeying around with the AC system on these, it becomes readily clear that planning on replacing most of it is a good bet, including some of the hard lines, especially the one along the firewall(on a '94, not sure on newer models).

The only way it really works right is if you can whisper in just the right amount of refrigerant and the system can hold a vacuum indefinitely. Otherwise, you are just throwing good money after bad. You can do it though. It's all just bolts.

 

[ZackR]

Probably in-op if it's empty.

Seems like there should be a fine or something if dudes are just pumping r134a into R12 systems. I am thinking there was a reason they have different fittings, different pressures, maybe?

.

I think the reason for the different fittings is to avoid mixing the wrong types of refrigerant.

Getting the right amount of refrigerant into the system is easier if its empty to start with rather than trying to add to an unknown existing quantity. Actually I can't think of a way to accurately know how much to add without emptying it first.

I agree once you open it up do everything right the first time....

 

[Red Merle]

I think the reason for the different fittings is to avoid mixing the wrong types of refrigerant.

Getting the right amount of refrigerant into the system is easier if its empty to start with rather than trying to add to an unknown existing quantity. Actually I can't think of a way to accurately know how much to add without emptying it first.

I agree once you open it up do everything right the first time....

I agree, but I would still wonder why it was empty in the first place. When I first got my truck, I jammed a can of r134a into and it was like an iceberg for a few hours, but it all leaked out and then upon further inspection, I had a number of issues and by the time I determined that I needed a bunch of surgery anyway, I just decided to just re-do 90% of it. It can be a frustrating process the first time around, but it's a doable job.

 

[BILT4ME]

The oils and refrigerants for R12 and R134 are incompatible and should not be mixed.

Typically for a change to R134, you need to replace the expansion valve, the drier, the fitting adapters, and change the oil in the compressor. It is the residual oil that is the biggest problem. It tends to clump with the R134 and it will eventually clog the expansion valve.

Do what you want. Pay him $60, have him warrant the system for 24 months and if it stops working for ANY reason, he will repair / replace parts at no charge.

I'll bet his tune will change.

 

[Red Merle]

Forgot about the oil. Great call.

 

[offroadvegan]

The system was evacuated by the PO. It was vac tested when I rebuilt the engine, so I know no leaks.

 

[Rifleman]

The oils and refrigerants for R12 and R134 are incompatible and should not be mixed.

This is additional info for the OP on the correct oil to use in his refit.
OILS USED IN AUTOMOTIVE A/C SYSTEMS
MINERAL OIL
Mineral oil is used in all old R12 (Freon) systems. It has worked well for years and would be the recommended lubricant for all R12 applications. R12 has a high affinity for mineral oil, meaning it takes mineral with it as it travels through the system. Mineral oil does not mix with R134a and there for not usable. I have specialized in air conditioning work and have been getting mineral oil on my skin for years with no ill effects that I know of.
PAG OIL (Polyalkylene Glycol Oil)
PAG oil is used OEM (Original Equipment Manufactures) in their R134a systems. PAG oils will soften paint which can be a major problem. PAG oils are harsher on o-rings and seals. PAG oils may cause skin irritations. PAG oil seems to give my skin problems when I work with it. I get a mild rash even from the vapors. It is recommended that you always wear protective gloves and goggles while handling or servicing a system with PAG oil. PAG oil is very hydroscopic (absorbs moisture from the air) and must be kept in closed metal containers.
POLYOL ESTER OIL (Retrofit Oil)
Polyol Ester oil (Ester for short) or retrofit oil as its' sometimes called is the preferred oil to use when you are performing a retrofit. Ester oil is recommended by most after market manufactures and rebuilders. Ester oil mixes with and is compatible with mineral oil. Ester oil can be used with R12 and R134a refrigerants. Ester oil is not as harsh to o-rings, seals and paints as PAG oils. This is the oil that comes in or is supplied with the compressors that come from Everco, Murray, and Four Seasons. When you are doing major repairs you could prepare the vehicle for later retrofit.

1. 
   You could:
2. Flush the heat exchangers and hoses.
3. Add an R134a compatible drier/accumulator.
4. Service with Ester oil along with R12.
5. Then add special service fittings, label and R134a when R12 becomes unavailable.

I have been told that Poyol Ester oil does not provide as good of lubrication as mineral oil when used with R12.

 

[maxamillion2345]

There is a Toyota TSB for converting early 80 series to r134a. Evac r12 and add pag and r134a and ignore the existing mineral oil. So sayeth Toyota.

 

[baldilocks]

http://tms.cleanautoalliance.org/documents/ac002t98.pdf

I followed this TSB when I converted my early 93 to r134a. Based on info gathered from other sources, if your system is solid, just have it serviced up with 134 and PAG 46 oil and rock on. Lots of references out there where it’s claimed that this is all that was done. The shop you spoke to probably has some adapters to make it possible to connect to your service ports.

My system was new to me and not working. With 270k and 24 years on it, I opted to replace my entire system which is why I bought the bag of retrofit parts listed on the TSB which cost about $80 iirc.

You might consider installing a new receiver/dryer first since they are cheap and easy to replace. There is nothing to lose, except a few bucks, by trying a 134 charge up prior to a full retrofit.

 

[flintknapper]

From retrofit instructions:

"B. System Performance A slight decrease in system performance may be noticed on some vehicles under certain operating conditions.

C. Refrigerant Pressures R134a high side pressures are greater than that of R–12 above ambient temperatures of 68°F.

D. Flushing Requirements There is no need to remove or flush R–12 mineral oil from the system. Simply charge the system with the specified type and amount* of PAG oil to provide proper lubrication.

E. Use of Sight Glass Mineral based R–12 oil remains and circulates in the A/C system and does not dissolve in R134a refrigerant. This results in a cloudy appearance at the sight glass making it impossible to judge the refrigerant charge amount by using the sight glass method. To prevent misdiagnosis on retrofit vehicles, apply black paint to the sight glass on block–joint (FF) type receiver/dryers. "

 

[offroadvegan]

So thanks everyone, this is awesome. but stupid question...HOW do you add the oil to the system??

 

[maxamillion2345]

Pull a line off and pour it in, or they make special injector things to hook up to gauges. Personally, with the system drained, I’d pull a line off and pour it in, and then let it all settle, and spin the compressor over by hand a dozen times. Then vac and charge.

Buy some conversion fittings, red loctite them on and go for it.