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I have a 1995 Chevy S10 4.3 4x4 manual trans and my A/C is currently not working properly. I had it charged with R-134A correctly and there is a small leak at the high side valve, but when we were charging the system the clutch on the compressor would click on for a second and click off. As we charged it more it slowly stayed on longer. The leak is still there and needs to be fixed, but a half hour after charging the system and getting it down to 39-40 Degree temp at the vents in the car, it stopped blowing cold and now blows hot air. The leak isn't all that great and the guy who charged the unit slightly overcharged to compensate for the leak until I got it fixed. Does the compressor clutch need to be replaced or is it just the leak that is causing the clutch to engage and disengage rapidly as a safety measure?
If you turn the A/C on now, other than blowing hot air.. Is the clutch on the compressor engaging?
It's peeing in the wind, at best, trying to diagnose things like this, other than in generalities. Now, if you had pressure gauges hooked up and could tell the pressures on the low and high side of things.. That might help narrow things down..
But, just first blush at reading this.. I think you may have a second leak that you don't know about.
It is definitely possible that there is a leak, when I had both the low side and high side connected it held its charge. If I need to get in further and diagnose another leak I will. Do you know how to replace the schrader valve?
It is definitely possible that there is a leak, when I had both the low side and high side connected it held its charge. If I need to get in further and diagnose another leak I will. Do you know how to replace the schrader valve?
Nope.. Not that good with A/C.. I can generally muddle my way through diagnosing a problem.. But.. Outside of replacing the stem on a tire.. Never changed or messed with the valve before. Though.. I did, come to think of it.. Have one leaking on an old Ford Escort, back in the ACTUAL freon days (I know, I still call it 'freon' and it's not, but..).. I think I threw that car away rather than fix it to be honest.. lol.
absent knowing the gauge readings and system temps (ie, condenser temp, fan operation, and evap core temp) one can only guess at the failures in this system ...
but the clutch apparently works properly to drive the compressor when energized.
when you start charging a "low" system, the low pressure safety switch will kick out the clutch to protect the compressor and system. Hence, the rapid cycling in and out at the time.
As you described, as the system was charged up, the clutch cycled in for a longer time. The low safety switch wasn't cutting it out then, and the system controls were cycling the compressor normally. Hence you observed the low temp at the outlets. It would appear that the system could function correctly, the refrigerant was flowing properly and the condenser/fan, evaporator/blower, compressor, clutch, expansion valve ... all items were working normally.
But then your tech intentionally "overcharged" the system. R-134a is sensitive to this, and can develop very high side pressures which can kick out an overpressure safety switch. Like the low pressure switch, it's there to protect the components and hoses from damage due to higher than normal pressures, and perhaps this has kicked out the clutch so the compressor is no longer turning.
OTOH, if the clutch is still turning the compressor, it's likely that the "overcharge" is too much refrigerant in the system; ie, there must be the correct relationship between the high side and the low side pressures for the refrigerant to flow. It's that flow that transfers heat from the evaporator to the condenser. So the system will deliver hot air because it's not absorbing heat at the evaporator and taking it away to be removed at the condenser.
Bleeding off the excess refrigerant would restore the system flow and cooling, but best done with the gauge readings to know what the system pressures are at.
If the system has leaks, then you need to use the standard tactics to identify them. Such as an electronic "sniffer" leak detector, dyed refrigerant, or soap bubble solution to identify the leak(s) location.
RE: Schrader Valve. R-134a systems were designed to be serviced by techs using recovery/recycling machines to safely remove and capture the refrigerant. So the process would be to remove and store the refrigerant, then remove and replace the Schrader valve at the port, evacuate and then recharge the system.
You MUST fix any leaks if you want your A/C to work and continue working.
This is simple and like a tire... A tire needs air. Period! If there is a leak in the tire, it will go flat and no longer work as it should. Fix the leak and end of problem with tire.
As they say... "Do it right or do not do it at all!"
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