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Installing an A/C High Side Port

jnstrawn

New member
Joined
Jan 13, 2021
Location
Vicksburg, Ms
I have a 1992 940 (my son-in-law purchased for my granddaughter) that has been upgraded to R134. There is no high side port to connect my A/C gauges to. Does anyone know of any aftermarket fix for this.
Other vehicles I've worked on generally have the high side port on a line coming from the condenser.
Thanks for any help.
 
Isn't there an overpressure relief valve on the high side of the compressor? You may be able to swap that for the charge fitting or make a tee adapter in that spot.
 
Let me do some investigating on the compressor. She just returned to school so it'll be a couple weeks.
If the compressor is a path to a fix, I don't mind replacing the one on it if it is not compatible. Being a retired Marine, I have plenty of money. :)
Can someone recommend a replacement compressor that allows addition of the high side port to connect my charge lines?
 
I'd love to know the thread pitch of the port. Should have measured while it was sitting on my bench :doh:
 
What is #26? That looks to be on the high side (condenser pipe)?

12409d1447903113-940-high-side-port-where-ac-parts-diagram-940-4-cylinderjpg.jpg
 
Some compressors being sold on the net look to have both fittings right at the manifold:

s-l300.jpg


I think it's always good to see what the HI/LOW pressures are to see how the system is performing. If the HI side is too high you may have restricted orifice valve, insufficient cooling of the condenser, overcharge. There must be a reason that most every manufactures offer fittings on both sides. That high pressure relief valve #26 is also at the very bottom of the system which helps when you evacuate it. Converting to r134 you want to get as much of the old oil as possible.
 
Unless you are having a problem, you don't need a high side fitting.

Just vacuum down the system, charge by WEIGHT thru the low side, and then enjoy A/C.
 
Nope, I do all me work from the low side. There are some high side Schrader valves that leak when disrupted and require an entire hose replacement.

Restrictions are uncommon.

I start charging, and then turn on the engine and A/C, and then let the compressor suck in the final charge.
 
Too little oil could seize a compressor. Too much could make it sluggish. There is no way to tell how much oil is left in the system. It is PROBABLY about right. I wouldn't worry about the oil capacity too much, but you could shoot 1.5 oz into it for good measure. It won't hurt anything.

I would just recharge it BY WEIGHT and then see what happens. Then monitor for leaks.

The capacity on a R12 240 was approx 2.5lbs. I would just blast about 2 lbs of R134 into into the system and see what happens.

Have you found a LOW SIDE fitting?
 
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Too little oil could seize a compressor. Too much could make it sluggish. There is no way to tell how much oil is left in the system. It is PROBABLY about right. I wouldn't worry about the oil capacity too much, but you could shoot 1.5 oz into it for good measure. It won't hurt anything.

I would just recharge it BY WEIGHT and then see what happens. Then monitor for leaks.

The capacity on a R12 240 was approx 2.5lbs. I would just blast about 2 lbs of R134 into into the system and see what happens.

Have you found a LOW SIDE fitting?

I guess I had gotten a bit spoiled with having the high side port. I usually connect to both to vacuum the system, then disconnect the high side and install a quick connect (just like on my gauge manifold set) with a digital micron gauge to give me a better indication if have any leaks anywhere; and how large.
Similar system to what I use for my home HVAC.
Wilco on the addition of oil.
Regards,
Jerrell
 
I'd love to know the thread pitch of the port. Should have measured while it was sitting on my bench :doh:

I know the high side on mine was a -4, but I have a dealer installed retrofit kit on my car. I don't have record of the low side, but I think it was -4 as well.
 
That's just a safety pressure valve built into the Lin e. There is no high side port stock.

I screwed a high-side port into this fitting because I couldn't get the machine I have access to to cooperate only using the low side hose. I can't remember the Sanden part # but I found it in an old turbobricks thread. Pretty sure I got it from the autozone hub.
 
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