Finding my A/C leak before compressor replacement.

[Scrufdog]

I recently bought my 1995 Suburban and the a/c compressor doesnt run. I dont have my gauges at the moment, so I tapped the high and low pressure ports with a screwdriver and noting leaked out. So the system is empty and the compressor bearings and squealing. At this point I, at minimum, will be replacing the A/c compressor, drier, and orifice tube. Before I do all this, what would you recommand I do to try and find the leak in the system? I figure I'll add some 134 with dye in it, get the old compressor running (assuming it can) and look for leaks. Assuming there is a leak, should I even bother trying to pull a vacuum on it first? I'd like to find the leak before I install all the new stuff.

Ideas?

Thanks

 

[IOWNJUNK]

Dye and blacklight. Works for the rest of the truck too, engine trans power steering...........

Youll have to waste a can of freon to charge system to check for leaks though. A small price to pay for a/c.

 

[98_k1500]

You can air up the system to around 100 psi with a rubber tipped blow nozzle on a air hose. quickly re-install the schrader valve and check for leaks with soapy water. I would bet the compressor o-rings are leaking. The orifice tube is behind the grille on these trucks btw. Don't use this method on a good compressor tho, as compressed air contains alot of water vapor that will contaminate the new compressor. As long as you pull a good vacuum on it, it will not hurt the rest of the system.

 

[IOWNJUNK]

True. He's replacing compressor anyway.

 

[Scrufdog]

i have a blacklight leak finder set, I'll try that route first, not too concerned about using extra freon. If that doesnt pan out, or if the existing compressor is totally shot I'll go the pressure method.

Thanks for the tips.

 

[98_k1500]

This method actually can be used on a good compressor if you change the oil in the compressor afterwards. Just a major pita and no guarantee that you got 100% of the water out of it.

 

[Scrufdog]

Update.

The compressor is shot to hell apparently. I put in 2 cans of UV 134 and ran the compressor. Sounds like a box of rocks in a blender. Never built any pressure, only held it for 3-4 seconds. I have a new compressor, drier, orifice tube, seals and stems, more UV freon and oil. From the sound of the compressor I should flush the system, as I'm sure it is full of junk. I've read up some of system flushing and have a few questions related to this specific truck.

1. Can I just pour a/c flush solvent into the condenser, lines and evaporators (rear a/c) and then blow it out with compressed air? What's your experience with doing this, and not removing everything form the truck first. I figure for the condenser, pour flush into the bottom line then blow from that side after a couple minutes of soak time. Then blow through the top line. Same procedure for the evaporators.

2. Do you think it would be a problem, as mentioned above, flushing the rear evaporator from the front of the truck? Obviously I wouldnt get all the big pieces (if there are any), but I would think with it being that far away it probably wouldnt be an issue. If any big pieces are that far in, and trying to blow them out wont get them, I doubt they would ever make it to the compresor.

Opinions?

 

[98_k1500]

Update.

The compressor is shot to hell apparently. I put in 2 cans of UV 134 and ran the compressor. Sounds like a box of rocks in a blender. Never built any pressure, only held it for 3-4 seconds. I have a new compressor, drier, orifice tube, seals and stems, more UV freon and oil. From the sound of the compressor I should flush the system, as I'm sure it is full of junk. I've read up some of system flushing and have a few questions related to this specific truck.

1. Can I just pour a/c flush solvent into the condenser, lines and evaporators (rear a/c) and then blow it out with compressed air? What's your experience with doing this, and not removing everything form the truck first. I figure for the condenser, pour flush into the bottom line then blow from that side after a couple minutes of soak time. Then blow through the top line. Same procedure for the evaporators.

2. Do you think it would be a problem, as mentioned above, flushing the rear evaporator from the front of the truck? Obviously I wouldnt get all the big pieces (if there are any), but I would think with it being that far away it probably wouldnt be an issue. If any big pieces are that far in, and trying to blow them out wont get them, I doubt they would ever make it to the compresor.

Opinions?

This is exactly what i would suggest. I have never had a issue doing this, i just keep flushing until it starts coming out clean. Even tho the compressor is shot, did the system hold pressure?

 

[Scrufdog]

it held a whopping 30psi for a few minutes before I disconnected everything, didnt have time for extensive testing that day. Going to check it today when I get home to see if there is still pressure in there. Either way, every seal I can reach will be changed. If it didnt hold pressure I'll check with my UV light, if nothing is found that way, I'm going to to do 100psi test on it and hope it's leaking somewhere up front and not in the back.

 

[Johnbalderas90k1500]

Recover the refrigerant and pull a vacuum up to 27 inches for about 30 to 45 minutes unhook then let sit for another 10 to 15 minutes under vacuum to check for leaks. Then recharge and check pressures

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