A/C question - where is the high press service port?

alia176 · #1 06-24-2007, 08:27 PM

Is the high press service port located on top of the Receiver/Dryer? If so, my R134 retrofit service port will not fit on top of OEM service port. Furthermore, if I were to remove the OEM service port, the threading is a different size than my retrofit service port.

What gives? Do I have to get some sort of a special R134 high press service port or am I missing the location of the oem service port all together?

Thanks for any help!

'92

SVXdc · #2 06-24-2007, 09:55 PM

I don't know if the '92 is different, but on my '96 the high-side service port is on a tube just above the compressor. The cap has an "H" on it.

The low-side service port is not too far away, hovering between the battery and the oil fill port. Its cap has an "L" on top.

I don't see any ports on the receiver/dryer, in front of the passenger-side wheel well.

alia176 · #3 06-24-2007, 10:03 PM

Thanks, it sounds like my '92 is a tad different. I bet my high press port is the one on top of the drier but dang if I can make it work!

longassname · #4 06-24-2007, 10:05 PM

I don't think so. I think both the low and high should be over by compressor. It's that way on both of my svxii

Quote:

Originally Posted by alia176

Thanks, it sounds like my '92 is a tad different. I bet my high press port is the one on top of the drier but dang if I can make it work!

ensteele · #5 06-24-2007, 10:30 PM

Correct - both are over by the compressor. There is a fitting on the dryer, but that is not the one you should use. Good luck.

SVXdc · #6 06-24-2007, 11:48 PM

There's a diagram in this thread:

A/C Compressor Installation

Looks like it was grabbed from SubaruParts.com. It's not annotated, but still might help a little.

The service port caps are 73474 (high) and 73474A (low).

So the refrigerant flow in the SVX is roughly clockwise? Where is the orifice tube hiding?

On a '95 Cadillac whose A/C system I just worked on, the low-side port is on the side of the receiver/dryer. If the one on your SVX is aftermarket, you might indeed be seeing another port there.

alia176 · #7 06-25-2007, 06:54 AM

Quote:

Originally Posted by longassname

I don't think so. I think both the low and high should be over by compressor. It's that way on both of my svxii

Looks like someone stole my high pressure fitting

Here's what my compressor area looks like:

Receiver dryer

So.....what can I use as my high pressure service port?

ensteele · #8 06-25-2007, 10:18 AM

Use the fitting that is in the red box in the above post.

alia176 · #9 06-25-2007, 05:02 PM

Quote:

Originally Posted by ensteele

Use the fitting that is in the red box in the above post.

That's not a high press port!

My gauge set (along with all A/C gauge sets) needs a high and a low service port for an accurate assessment of the A/C system, evacuating and recharging of R134.

So, is my '92 just unique or is Subaru wanting us to use the port on top of the receiver/drier? I wonder if the Subaru OEM R134 retrofit kit includes an adapter that fits on top of the port that's currently on the receiver/drier?

alia176 · #10 06-25-2007, 05:06 PM

Quote:

Originally Posted by SVXdc

The service port caps are 73474 (high) and 73474A (low).

So the refrigerant flow in the SVX is roughly clockwise? Where is the orifice tube hiding?

On a '95 Cadillac whose A/C system I just worked on, the low-side port is on the side of the receiver/dryer. If the one on your SVX is aftermarket, you might indeed be seeing another port there.

Clockwise, guess so...sort of relative I guess. Orifice tube is inside the car, next to the evaporator.

I think you may be on to something, I may indeed need to use the receiver/dryer fitting but over the shelf retrofit kits don't have R134 fittings for it! I'll take a swing by Subaru to see what gives!

Thanks

dannmarr · #11 06-25-2007, 09:41 PM

What do you need the ports for? Reading or charging? I'm not sure about cars, but when I work on chillers, I charge the system on the low side.

ensteele · #12 06-25-2007, 09:51 PM

The port that is shown in the red square is where I have always charged mine. I draw a vaccume and then charge it there.

No problems so far.

SVXdc · #13 06-25-2007, 11:03 PM

Quote:

Originally Posted by dannmarr

What do you need the ports for? Reading or charging? I'm not sure about cars, but when I work on chillers, I charge the system on the low side.

You attach meters to both service ports. They have different scales, because the high pressure side is about 3-4x the low.

You should charge into the low side. Yes, if you evacuate the system the vacuum would draw refrigerant into the high side initially. But you'll eventually reach a point where you need to run the A/C compressor to add more. The pressure of the refrigerant inside the can won't overcome the pressure coming out of the high side of the compressor, so no more refrigerant will be added to the system. You'd also risk having the can explode in your face.

Useful links:

Automotive Air Conditioning Systems at familycar.com

Troubleshooting with Gauges FAQ at aircondition.com

ensteele · #14 06-25-2007, 11:47 PM

Those are very good sites. Thanks.

alia176 · #15 06-26-2007, 05:31 AM

As stated above, it's important to use both service ports for diagnosing, evacuating and recharging the A/C system (through low press port) properly. What I'm trying to do wouldn't be a biggy if I were to use R12 manifold gauges but this is becoming an issue for R134 gauges!

If anyone with a '92 has converted over to R134a, can u shoot me a pic of your high and low press ports, detailing the R134a nipples? If you have installed a R134a high press fitting over the receiver/dryer high press port (see my pic above), where did you get that nipple?

Thanks.