AC Service Port Question
 

I've been working through problems on the AC, and the past threads have been hugely helpful. I've gotten to the point where I want to try to get some R134 into the system, but the low/high ports have me utterly confused.

The low port is underneath the radiator hose on the right side of the engine correct? If so, mine seems to have a larger high port fitting on it.

The high port fitting (I think is by the drier, next to the low freon switch) seems to be the smaller conventional low port fitting, so that's the only one that the cans of freon will attach to. Did the PO just put the fittings on the wrong places?

I know from reading the threads I want to fill on the low port side. Seems simple enough to swap the fittings, but my system already has a vacuum and is ready to go, so swapping fittings will lead me to have to take it back to get evacuated again. My local auto parts store doesn't sell an adapter.

What am I missing here? Or should I just bit the bullet and swap the fittings?

Thanks in advance...

You can fill the system from a vacuum on the high side, by WEIGHT, as liquid.

Then let it sit for 20min..let the liquid evaporate evenly into the system, then fire it up.


Ideally, yes, you would fill from the low side...but let the vacuum pull in XXoz of 134, by weight, then stop.

Fill the high side while the car is off, right?

Yes, if the compressor sees any liquid refrigerant from the low pressure side it will fail.

Plus nobody wants to work in a hot engine bay :)

If you are using an AC Gauge manifold, just reverse the hoses on the manifold or the adapters and remember which one is which when you fill the system.

Yes, thats why "fire it up" was after the 20min of waiting. :)

Well, it wouldnt run without enough in it anyway...much less under vacuum.

Swap the fittings before you start working on the system; be sure there is no refrigerant in it before you do.

Larger diameter goes on the high side by drier,
Smaller diameter goes on low side under the rad hose; where a leather glove if things get hot when R&R the service hose.

This was well worth the investment...

https://cimg4.ibsrv.net/gimg/rennlis...20a80ec307.jpg

I couldn't get any to go in via the high side port, so, I ordered a set of gauges and a vacuum pump earlier today. I'll swap the fittings, put in new vacuum, and try to get some R134a into the system. Then on to the next step...

Thanks everyone for the advice!

Just reading this thread; sorry I'm late to the party.

The original R12 low side port connection is larger than the high-side port connection. For R134a, the high side is larger than the low side. Using commonly available adapters, it's almost impossible to get them reversed -- I've never seen a small high-side R12 to small low-side R134a adapter.

[scratches head...]

+100

Hi just read this too, are the connections for the AC a push on "quick connect" type or a screw on type?

Dave

They're push on. I think the PO really just mixed the connections. I know I could probably reverse the manifold gauges and do it that way, but I really want to get it done the way it should be done, especially since this is really the first thing I'm taking on with the car. So, I ordered gauges and a vacuum pump and will put on new fittings just in case.

This puzzled me too. I wonder if the PO had not converted the ports for R134a, or maybe not converted system at all?