Chevy Truck A/C Question

I have a 1996 Chevy Silverado pickup that the A/C wont hold a charge very long and was told by previous owner that the evaporator has a leak in it. friend told me about some stuff called Red Angel that can be put in system and will stop the leaks and works great(little pricey} and probably just a quick fix. the evaporator is not that costly but I guess its a real pain to change so i'm told anyone have any experience with this stuff?? or verify if it does work or not any input greatly appreciated..

If your leak is at a seal, then some of these aftermarket remedies can work quite effectively -- but are still only a temp fix. The seals will continue to degrade over time.

If the leak isn't a seal, then there's much less chance that these remedies will work.

Some people swear you should never use such remedies. Me? I dunno. I've used them myself, with limited success. Way I figure it, I could either find the leak and try to make a permanent and proper fix, or I'll wait for the thing to self-destruct beyond repair and then pay the big bucks for professional repair/replacement. ....Either that or install a window A/C and carry a long extension cord! :shock:

Check the valve cores at the charge connections. My son had a pick-up that wouldn't hold a charge, turned out to be a leaking valve core. Good luck.

Look for a leak of refrigerant oil. Sometimes it will help find the leak. Shows up as dust collection on the oil.

(quoted from post at 07:27:06 08/18/18) I have a 1996 Chevy Silverado pickup that the A/C wont hold a charge very long and was told by previous owner that the evaporator has a leak in it. friend told me about some stuff called Red Angel that can be put in system and will stop the leaks and works great(little pricey} and probably just a quick fix. the evaporator is not that costly but I guess its a real pain to change so i'm told anyone have any experience with this stuff?? or verify if it does work or not any input greatly appreciated..

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WHY NOT FIND THE LEAK !!! If you insist on dumping that chit in it at least tell the guy that's going to fix it you dumped stop leak in it... Those compressors were born to leak I would bet my hat that's were your leak is no stop leak is gonna fix it... I don't remember ever putting a evaporator on one like yours unless it was damaged while replacing the accumulator are some dumb arse put stop leak in the system...

If you dump stop leak in it don't be surprised when a shop tells you the system is contaminated and the complete system needs to replaced...

Hobo is 100% right. Don't put that garbage into your system. It will only complicate doing the real repairs later.

No experience with that brand, but AC stop leak has been successfully used for a while now.

If it's a pin hole leak in the evap or condenser, good chance it will stop it. But a leaking seal, oring, or rubber hose, no it won't have a chance.

How was a leaking evap diagnosed? If a leak detector sensed refrigerant inside the case or duct work, chances are it is the evap. But give it a good visual, many times a shop of owner will not be able to see the leak, and just assumes the worst, blames it on the evap.

If you do use the stop leak, read the instructions carefully. It doesn't go in like refrigerant. It has to be coaxed out of the can. Do not run it through your gauges!

That sealer stuff cost me a $3500 reclaimer 15 years ago. I was doing a "favor" for a friend. He wanted his car's system checked out. I usually only worked on tractors and combine systems. I did not have filters on my lines. I went to pull a vacuum on his system and sucked some of that leak sealer into my machine. Locked up the vacuum pump right then. I took it apart to see what the problem was. This was later at night. I quit and came out in the morning. In that time frame the stuff had glues the valves on the high and low pressure side.

I tried everything I could think of the clean that crap out of the lines and such. The vacuum pump was not that high. The rest of the system was polluted beyond repair.

When I replaced the reclaimer They showed me filters that stop you from getting it into the heart of the machine. You still are out a set of filters and the hoses that go to them. About $100 out the window.

I can't advise you as to how to find the leak but I can tell you about replacing an evaporator. I had to replace mine because of a mouse nest that I couldn't get all cleaned out. It restricted the air flow so badly that there wasn't much air coming out. The air was cold but there wasn't enough of it to cool off the cab.
I spent the better part of 4 evenings tearing the dash out, replacing the evaporator, replacing some of the dampers and putting it all back together.
Process was as follows, as I can remember it...
Remove driver's seat to allow enough room for the steering column to drop to the floor. Remove all lower dash covers. Remove nuts holding steering column and lower it. Remove dash screws up at the defrost vents. Remove bolts on either side of dash which holds it in position. Remove one bolt way back above HVAC box. At this point you should be able to tilt the dash downward and with the help of someone else tilt and lift it off the pins on either side of the cab. There are some wires and plugs to un-do along the way. Once you get the dash out of the way you can unbolt the hvac box, disconnect the AC and heater hoses etc and remove the entire box. Disassemble and rebuild as necessary.
Reverse procedure for re-installation.
Not really for the faint of heart but if you're used to working on vehicles definitely doable.

Those few years were notorious for the compressors to leak, unless they start leaking bad they can be hard to find. The leak comes from where the halves meet in middle of the housing. You can quickly unbolt the compressor and look at the bottom, or a small inspection mirror and flashlight will let you see the bottom. You are looking for oily residue, green dye.

The blower motor and blower speed resister are pretty easy to remove (under glove box) from there you can cram your head down there and take a look at the evaporator, or use the inspection mirror and flashlight to find the green oil/dye. A UV black light can help too because the green dye is also fluorescent

leak testers are $20
https://www.google.com/search?q halogen leak tester

I agree with 4play hose compressors were notorious for the compressors to leak at the two large Orings on tje main body ring.Stop leak won't stop your leakfor long if at all.Replace the compressor for a lasting repair.

Learned my lesson on stop leak in a 94 Caravan I was trying to keep running with over 250K on the clock. Don't do it, find and fix the leak. Even if it is the evaporator the job to replace it will be allot less work than continually having to fix/replace plugged expansion valves and other components in the system.

A leak sniffer is the best way I found to find/confirm a leak. My 2000 Silverado also has a leak but takes almost a year before the compressor starts cycling and I need to add a can of 134.

Old retired dealer mechanic friend told me how best to tell when it's full without gauges. Put a thermometer in one of the vents, fast idle, fan on full. When the temp on the thermometer stops dropping, quit.. It's as good as it's going to get.

I use a remote sensor digital thermometer I got off eBay for cheap. Set the readout on the dash with the probe in the vent so I can see it from outside the truck