[bl665]

So I havn't been having AC for a while now. In this heat I'm really getting irritated by it. So I charged the system with 30 lbs of R-134a and It lasted roughly about a month.

I thought there was a leak so I got the UV R-134 and charged via Low side port.
It was about 12 ounces.

It comes to find out I think I have a leak from the valve on the High Side port since I noticed small air bubbles and the Green(UV) ink was inside the cap.
Which it shouldn't be since I charged it on the low side.

When I took the valve off I let the remaining pressure out of the system via the Hgh side port. A good amount seemed to come out pressurized.

Does this mean that my system holds a charge but doesn't get cold ??
Ive looked around as well (with an actual Flourescent black light) and I cannot see any more leaks

I have looked at the DTCS for the AC as well. It's just the codes I have dont seem to match up to the ones in the car(unless Im reading it wrong) Is there one specifically for the 96 280 sports

Also I've read the cabin air temp sensor could be bad. The one I have used to buzz (Ive read this is a sign of it being bad) Now it doesn't anymore.

I'm going to replace the valve but would like to know more as this heat is killer.

Any help on this situation would be greatly appreciated since I drive back and forth to the dessert :surrender::surrender::surrender::crybaby2:

Thanks in advance

 

[marvinstockman]

First, you always charge by the low side, not by the high side.

You need to go to Harbor Freight and get a cheap set of gauges, as you can't just dump R134 and a can of leak detector into the system.

You also need to read up on how an auto AC system works.

That said, you can replace the core of the high side port. It's just like a tire valve core.

 

[bl665]

I did charge by the low side. I just noticed that the high side port was leaking the fluid. Which it shouldn't be due to the fact that I didn't charge from that side.

It was inside the cap if you know what I'm trying to describe.

Yes I know I'll be getting one shortly so I know how much Pressure is in the system.

I figured though, that if my system was leaking there would be no pressure in the system at all. Correct me if I'm wrong

I get cold air when I first charge the system eventually it goes away.
Its either due to losing charge or a faulty component in the system.

This is what I need help diagnosing.
Could it be a bad condenser ? and how could I test these units ?

 

[kmax7]

As Marvinstockman said get a R-134a gauge set. You should have a static, car off, pressure of about 90-100 PSI (both low-high sides) after car has not been run overnight. When operating you should have 30-50 PSI low side and 200-300 PSI on high side. Pressures are really dependent on heat load, outside temp and compressor operation. There are a lot of variables for pressure measurements, so the most accurate way to measure is to pull the gas out and recharge by weight. As recall should be about 910g (32oz) of R-134A total.

If you have a slow leak you could still have some pressure in system but not work. It only takes a few of oz. of lost R-134A to cause the A/C to stop working.

Sounds like you have a leak, if large leak should show up with UV dye. If leak small will not show up with dye as in oil and you would have oil leaking as well. To find small leaks need to use a R-134A sniffer tool. Find a shop that has a sniffer and have them find it. Likely the compressor shaft seal is leaking, most common leak point.

 

[georgebuhr]

Save your money on the guages. Oreillys sells a nifty can of freon with a guage built into the can that will get you plenty close enough to charge your air without spending extra on guages. I've used it and was pretty impressed with the results. Also, your car has a bubble in one of the lines near the rad support that will show if the system is full yet. You can charge until you no longer see bubbles circulating in the line.

Change the high side valve, in fact with as cheap as they are you may want to just do both valves. The only other most likely place for it to leak is the seals on the compressor. Look for alot of dirt/oil around the compressor, thats an indicator that its leaking. Agree that your system can still be under pressure, but not enough to kick off the pressure switch which allows clutch to engage.

I doubt the cabin sensor is causing it to not work.

When charging, turn ac on max everything, check for cold air. Your lines under the hood should get cold as well indicating fluid is circulating. If its not circulating, but you have a full charge, then time to look at a pressure switch or possibly a clutch. If circulating but on normal settings no air, THEN I might consider the cabin sensor, or some faulty blend doors.

 

[bl665]

Thanks so much for the Info. I actually have one of the gauges at work which I'm going to be checking out today. Since I let all the R-134 out already I'm going to use our a/c machine at work again after I replace both valves and re-charge it.

You say the compressor leaks oil.

Well when I changed my belt recently and my Water pump I really wanted to take the portion off of the engine that held the A/c on to clean it up. There was plenty of wicking oil on that side of the engine block near the A/c compressor but I didn't get into it because I was worried about oil from the block leaking out. I'm not sure but I think It also has a crankcase ventilation that goes up to the intake manifold as well.

I was thinking I could get to all that from the bottom without removing the Water pump again ? Have any of you had any luck with that ?

 

[kmax7]

Good idea to replace shradder valves while have no Freon in system, after replacement, pull a vacuum, add UV dye and measured amount of Freon, that way any large leaks should be visible, unless in evaporator. Don't leave system open to atmosphere too long or the receiver/dyer will saturate with water and not keep the system dry in the future. Water vapor in an A/C system will kill the efficiency and break down the oil.

The A/C oil from a leaking compressor shaft seal occurs at the compressor as is the lowest part of A/C system and oil tends to pool there. So if you have a leak, oil will come out with leaking freon. If you have an engine oil leak on head/valve/crankcase vent and oil have leaked on compressor it will be hard to see if leaking A/C oil. The UV dye will tell you if the leak is fresh. Again has to be large enough of a freon leak for oil to be visible. The shaft seal is behind the A/C clutch. So you would see oil coming from between the clutch plates.

How fast to you loose A/C cooling after charging with R-134a?

 

[bl665]

Awwww I Didn't know or think about the leaving the system open I Just put the Valve back in. It was out for about 2-3 days in the garage. Do you think it will be ok ??? Thanks for that. Glad you pointed it out. !!

Ok well I did take a UV light to the compressor area and I didn't see anything at all that had to do it leaking otherwise I would have noticed it. I did notice the oil though but it could be from the oil pan. I haven't cleaned that side of the engine off yet actually.

ANd that last time I charged it with the MAchine at work put 32 ounces in it it lasted about a month and a half ?? Then it went hot again

 

[kmax7]

1.5 months is a pretty big leak. You might want to just add 1 can and have a shop find the leak using a R134A sniffer. That way don't waste another $50 on Freon. Just a thought.

Once you have found and repaired leak, I would replace the receiver/dryer.