A/C issues - 97 Sub K2500 454

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Bouncytruck

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I have a '97 Suburban K2500 with a 454. The A/C isn't blowing cold so added a can of R134A to recharge it. The compressor engaged intermittently but not fully. I added a second can and I'm getting similar results, but the compressor is engaging longer. The second can had UV Dye. I ran a black light over the engine compartment, but I don't see significant signs of UV Dye.

Should I add another can?
 

Schurkey

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What are the system pressures? Adding refrigerant without knowing the pressures is irresponsible.

Adding refrigerant to a leaking system (you suspect you're down by 3 pounder cans, so the system "apparently" is near -empty) without fixing the leak(s) is similarly silly.
 

Bouncytruck

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The pressure gauge (the kind on the can) started at 0. After the second can, it is reading above 20 when the Compressor cycles on. After the second can, the compressor is staying on longer than it did after the first can.
 

Schurkey

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The pressure gauge (the kind on the can) started at 0.
Not only do you need to find and fix the leak, you probably need a desiccant bag as well. The desiccant bag likely requires replacement of the accumulator.

If this were me, I'd take the opportunity to REPLACE EVERY O-RING IN THE ENTIRE SYSTEM.
 

Bouncytruck

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I looked for the leak in the front, but I hadn't even considered the rear A/C.

I think it's time to take it to a shop.
 
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bugdewde

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You really need a set of pressure gauges. Parts stores will lend/rent them out.
Cheap sets are at harbor freight for $50 (what i have).
May be able to find a used set on craigslist......

Check out the bottom of page 1 in my recent AC thread below to see the chart for max pressures you should be seeing..... based on the current temperature and humidity (which you'll also need to know - weather channel or phone app).
https://www.gmt400.com/threads/weird-hvac-behavior.45863/


Also, while monkeying around with my system, I watched many videos on AC diagnosis with pressure gauges. This guy does a real good job of explaining the AC system.
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There are other related videos you can watch as well (see side bar for related videos). That guy does a good basic explanation that worked well for me.
 

bugdewde

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My thread I just posted has some good info in the pics from the service manual showing components/locations. Also some good descriptions of what they do.

........ Most hidden/unseen leaks would come from the evaporator inside the dash or the evaporator in the rear......
You'll have to remove your blower motor under passenger dash to see the front evaporator ..... The motor is easy to remove...... however, the blower motor cover is a real pain. I'd consider just cutting the cover off next time I go in there. Lol.....

Use your phone to video inside there.... That's what i did to view inside the housing. Phone cameras are amazing at getting in tight spots!!!
 
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Schurkey

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Or cram the leak-tester probe inside the evaporator-box drain after removing the duckbill. Way simpler than prying out the blower motor.
 

L31MaxExpress

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Its probably not an evaporator anyway. The GM charge ports with those stupid plastic balls love to leak. Also the compressors used on these have a nasty habit of leaking at the case orings which means replacing the compressor. If the compressor is leaking they usually drip pag oil onto the compressor mounting bracket.
 
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