connecting manifold gauges

[ford_nut]

Hello all
I read to above post on how to recharge an a/c system. However, nowhere in the posts does it address the issue of what to do if the high side manifold hose wont screw onto the fitting. My low side hose went on just OK but the high (red hose) will not screw on the fitting (located on the hose). What gives? Do I need some kind of special adapter to screw onto the existing fitting so I can attach the hose? Something is screwy because why would the low side screw on with no problem but the high side doesnt? My gauge set is a brand new robinair and is for R-12 systems. If I need an adapter, where can I get one?
thanks
Ben

 

[shamaal]

As you have noticed, the R12 fittings are a screw type schraeder hose of different sizes.

The R134a type hoses are a quick disconnect (QD) type of different sizes. The pic below shows the LOW PRESSURE QD on the accumulator. I don't have a pic handy of the HP side (Driver going to condensor), but it looks similar only a different size.

Without seeing a pic of the fitting you have I am guessing that a previous owner may have installed a post R134a set of hoses (with QD). Another possibility, if it is indeed a QD fitting on you HP fitting, is that a previous owner converted to R134a and then removed the adapter fitting on the LP port because they are notorious for leaking.

All of this, of course, is conjecture on my part. Posting a pic of the HP port and your R12 hose would help in the diagnosis.

Possible ways to proceed are:

1. Evacuate system, then add a R12 load (32 oz Haynes).

2. Convert to R134a, change accumulator and orifice, flush system, add 7 oz of PAG oil and add 22 to 24 oz of R134a.

 

[ford_nut]

I did a double take on the fitting sizes again; they are definitely NOT quick disconnects. Both are the screw on type. The high pressure side however, is smaller. I just bought a set of new robinair gauges and 6 cfm vacuum pump. I have a freeze 12 kit ready to go in. However, I cannot evacuate the system because I cannot hook up the high side hose to the port since the connection is smaller than the 1/4 inch fitting that is on the robinair gauge set. . I will post pics shortly just to show what I am taking about. Thanks for the quick reply!!

 

[ford_nut]

I cant post pics for whatever reason. I just took a few to share with everyone but I guess its a moot point since I am restricted from posting them!

 

[shamaal]

pm sent, I'll post pics.

 

[shamaal]

Got it, I've posted pics below.
NOTE: THESE ARE FOR A FIRST GEN R12 INSTALLATION
CAPS added for anyone referencing pics later.
If I'm missing something here someone else chime in, it's been a while since I messed with R12.

The first pic is the Low Pressure Port, the second is the high pressure port, the third, and most important, is the hose.

The Robinair 30336 red hose is a good generic a/c hose that requires an adapter on one end to use in a R12 automotive air conditioning application.

Technically, you are looking for a 1/4" MFL X 3/16" FFL adapter. Ask at any A/C place, they are a common item. I doubt if the automotive stores carry them, but then I never looked, Wal Marts may. I've attached a picture and a URL with a pic.

http://www.sjdiscounttools.com/rob10468a.html

While you are at it, check your fitting to your R12 supply (can tap if applicable) so that you have the right one.