Low on refrigerant. Inject some dye, recharge, then use blacklight to locate source of leak.

 

Should I buy the dye separately from the refrigerant, or should I get a can of refrigerant w/ the dye in it. When I initially charged this last year, I put in just regular non-dye R-134a.

By the readings, not sure if a whole can (12oz?) will be able to fit or not.

 

Quite honestly the correct way to do it is to completely evacuate the system, draw minimum 15 minute vacuum, then inject your dye, followed by a complete charge according to refrigerant weight. However, many people choose to charge according to the low side pressure reading. This is not at all accurate since ambient temperature, among other things, will play a huge roll on actual low side pressure in a properly operating system.

That being said, if you choose to simply top up your system, since you can not be sure just how low you are; I'd recommend purchasing the dye separately. Inject the dye FIRST then chase it with the refrigerant to full charge.

 

Thank you RangerStang. I know that's the proper thing to do and I would if it were not for 90+ degree weather and driving around in this stang with black leather + no A/C is tough.

With the pressures that A/C gets to, does it make sense to have a slow leak like this or is the better guess that the refrigeratant is seeping out slowly?

The suction and discharge and sight glass lines are all the r12 style and AFAIK original. I did do one heck of a job cleaning them and the evaporator out before putting in rebuilt compressor & new condenser + drier.

I didn't grow up with R12, and I tend to remember rumors that r135a is a smaller molecule and has a tendency to do this.

Put any rumors to rest for me, please.

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Ranger is absolutely right on pulling a vacuum on the system. It serves two purposes. It removes non condensables, AKA, air. It basically takes up space, makes it run hotter and work less efficiently. The most important is it removes moisture. When you pull a deep vacuum, water will boil at 70*f. I just installed CA in my house. I let the vacuum pump run all night and shut it off in the morning. When I came home from work I checked to see if the vacuum had changed due to minute leaks that wouldn't show up right away. There were no leaks, vacuum was the same.

 

Ricer, what rumors have you heard about R-134A? There's a lot of funny misinformation about it.

In general, it is a decent refrigerant, and matches up well with R-12, except for low temperature applications (like freezers). It does require a bit more compressor and condenser capacity than R-12. It also is not miscible with mineral oil like R-12 is, so you need to use a synthetic oil like PAG or POE. The mix of R-134A and synthetic oil can have seal material incompatibilities with old R-12 systems, leading to leaks. R-134A low side pressures are slightly lower than R-12, and the high side pressures are slightly higher. R-134A has a great affinity for water, and will do a nice job cleaning out your system (so a new filter/drier is a must when converting). It is not corrosive or flammable.

The first part of your video seems like a system low on charge - pressures are low, especially on the suction side. On a 90 degree day, I would expect you to see something more like 30-45 psi on the low side and 150-200 psi on the high side.

The second part I assume it what happens when the compressor is off. Your system seems to equalize awfully fast. That could be from bad valves in the compressor, or it could just be a fault in your gage manifold.

R-134A is cheap, and I doubt you have even a pound in there now. I second the advice to pull the charge and re-evacuate. Pull down to a 30 in. Hg vacuum for about half an hour and then shut off the vacuum pump. A rapid rise in pressure indicates a leak somewhere.

Good luck,
MrFreeze

 

Thank you all!

I ended up putting in a full can of refrigerant, but before doing so, I rented the leak detector kit from AZ that comes with the hand pump to put the UV Dye into the system. I put a 1/4 oz (1 applications worth) in and followed it up with the R134a.

The A/C is blowing nice and cold again. I have to figure out how to get the moisture/condensation around the Evaporator to drain to the passenger side better, but that's a minor inconvenience.

Initial troubleshooting with the dye has not lead to any large or even minor leaks.

Just to note, when installing the condenser & newly rebuilt compressor, the drier was replaced at that time. The only thing that was not replaced was the evaporator.

I'm going to try and tear apart the housing around the interior unit to solve the drainage issue. While I'm in there, I'll try to see if I see any UV dye around the Evap.

Thanks all for your assistance!