Hey guys just recently bought my 95 z71 and I recharged the AC, it was blowing cool air while the charge. Three hours later I get in and take off and nothing but hot air comes out again :/ what do I check for next?
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You've most likely got a leak and thats where I would start. Check if your compressor clutch is engaging when you turn the system on, if it doesn't, the system is most likely low on refrigerant and is keeping the clutch from engaging as a self preservation safety. Take it to any decent repair shop and they'll be able to insert dye into the system and re-pressurise it for you to check it, or have them check it. That's IF it already doesn't have some dye in there. As old as these trucks are, thats a big if. Invest in some ac inspection glasses. They make the green of the dye pop out that much more.
Common places for AC to leak are:
-Condenser- rocks and road debris can potentially strike the front mounted condenser and puncture it. Even if you dont see the actual crack, if you see green dye around some fins or along a joint, its most likely leaking. Remember, ac systems are pressurized so it doesn't take a big hole for a leak to happen.
-Lines and joints- anywhere that you can see one material mating with another(rubber section of a line to metal section, etc), or a component bolting onto a line is fair game for a leak to happen. There are o rings and seals at all of those joints that could be the source of your leak. While checking your lines also make sure they aren't chafing on another hard surface that might be eating them through due to vibration.
-evaporator core- check the evaporator discharge grommet for dye. If it's green and oily, you most likely have an evaporator core leak. This would be worst case scenario, not a fun job. Unfortunately a lot of debris, leaves, twigs, rocks, dirt, and grime find themselves into the evaporator core housing somehow, and with nowhere to go they just pile up there and start to compact and retain moisture until they either rust out the welds in the core, or the difference in expansion and contraction temperatures from the areas with and without debris warps the core and a crack develops. I've attached a picture of what an evaporator core in these conditions will look like when removed vs a new one.
- AC compressor- compressors can leak not only from the rear where the lines go, but the case itself can leak, and the seal in the driveshaft behind the clutch can also leak. My truck recently kept loosing refrigerant very slowly and I couldn't see a leak anywhere. Finally ended up taking off the clutch and found the center of the compressor all green and oily.
Lucky for you, based on the very short time it took for your ac to blow hot again, you've most likely got a very large leak, that is most likely accompanied by a very large green spot of dye. Also lucky for you, most evaporator core leaks are very slow leaks, so you might have lucked out there.
If you have a shop check your pressures and they determine there is no leak, then you may have to start looking into electrical issues, bad switches, bad compressor etc.
Best of luck to ya!
Deve
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