New Air Compressor, what now?

[AnahRabekka1501]

I have an ‘89 Ranger xlt super cab and I just put a new air compressor in it, the one that was in it locked up 10+ years ago. I have a guy who tells me he has the vacuum and will do it free, but I need to replace the filter first. I have no idea what he is talking about.
Also, I would like to charge it myself, it was a brand new a/c so it has no remnants of R12 in it, is there a way to charge it the 2.5lbs I need to without paying $30 a pound to have a professional do it? Maybe can I use 134a or FR12?

 

[adsm08]

I would use R134a. It is cheaper and easier to get ahold of that FR12. R12 is pretty much non-existant anymore.

The most accurate way to do it would be with a scale and a can. I bought myself a scale, cheap vacuum pump, and a 30lb can of 134a earlier this summer, because I needed to do work on the Expedition with rear air (4.88lbs system capacity) and I could get the 30 lb can cheaper than buying 5 lbs worth of A/C Pro or ArticFreeze.

That is the most accurate way to do it. If you have a food scale and a few 1 lb cans (actually only 12 oz, but w/e) you can do it yourself pretty easy. Just hook it up, turn the AC on, and let it run until you get the desired amount in.

 

[AnahRabekka1501]

That’s really good to know. So I can just throw 134a into my old R12 air compressor? And do I need the little adaptor for the thing?

 

[55trucker]

That’s really good to know. So I can just throw 134a into my old R12 air compressor?

uhh...was that original compressor running with 134a & PAG oil in the system?

 

[win]

Commonly no, you can't just drop R134a into an old R12 system.

Most R12 systems used a mineral oil for the compressor, R134a won't properly return mineral oil back to the compressor.

Typically, R134a systems use PAG oil and R134a retrofits into older R12 systems use Ester oil.

Easy answer is to pull the R12 compressor, drain the oil from it and reinstall using Ester which will blend with the residual mineral oil.

R134a does weigh less than R12 so use 81% by weight of the R12 spec when charging.

 

[AnahRabekka1501]

It’s a brand new compressor that has never been installed on anything before my ranger. No oil, no remnants, nothing. I’m just curious as to what I do now. I heard I need to replace the oriface filter, then vacuum, then charge it. Even with nothing running in it before, can I charge it with R134a?

*Edit* thank you for the wonderful info on the charging ratio Win!

 

[4x4junkie]

Standard procedure is to replace the accumulator and orifice tube whenever the system has been opened to the atmosphere and/or has been non-functional for some time due to low freon. With it getting close to 3 decades old, it probably wouldn't be a bad idea to replace all the rubber hoses too.
If the original compressor locked up, it's also wise to replace the condenser (in addition to the above), as it is essentially impossible to flush the debris from a failed compressor out of it's many passageways, and anything floating around in there is likely to ruin the replacement compressor.

Since your replacement compressor is new, it was probably designed to use PAG 46 oil. I suggest using that with R-134a (of course making sure all traces of the old mineral oil is flushed out of the rest of the system). Ester oil is generally used if the compressor itself has already been ran with R-12 & mineral oil.

Finally, check that your compressor wasn't shipped with oil already in it (many are). I would recommend draining whatever is in it and start with new oil rather than mixing oils (that is unless it was clearly labeled as being shipped dry).


On this R-12/R-134a charge ratio thing...
When I had a shop charge my '90 BII years ago, the guy (who seemed knowledgeable) explained to me he puts in the same amount (weight) of R-134a as you would R-12, and that he has not had any issues doing so (but charging to a lower weight had brought many complaints that it wasn't as cold as it should be).
Indeed, I have seen temps as low as 36° out of my vents (generally it hovers around 42-44° or so if it's real warm outside and the blower on max). I don't recall if this is something specific only to Fords of this vintage, or if it's for all R-12 - R-134a conversions, but it would seem to make sense that it could be a source for the common complaint that converted R-12 systems are not as cold as with the original R-12 (certainly if mine was any colder, I'd have issues with the evap freezing up and blocking the airflow).