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Discussion Starter · #1 ·
I've got a 2004Envoy with 5.3l. I just put a reman a/c compressor, had system evacuated, and refilled. It just don't blow real cold? Its cold, but not cold like the old R-12 was. Is this normal?
 

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Discussion Starter · #3 ·
Yeah it should be between 38-45 moving and 50 at idle.
Thank you for your answer! That's about the temp I'm getting. I just thought it would really crank moving! Warm/Cool at idle. Cool not cold moving. But that's cool, I just was wondering if I could make better. I'm happy.
 

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I have an 02 4.2 LT. I see as low as ~30 to 32 or so at highway speeds on a freshly evacuated and recharged by refrigerant weight system.
 

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This problem is exactly why I always suggest the "Intelligent Expansion Valve" for R134a.

It is capable of changing the orifice size to compensate for thermal loads - all by itself.

But - no matter - the system can only get as low as the freezing point of water - depending on the local humidity factor, elevation and air density at that moment. 32°F is not usually achievable in an AC system.

The problem is that if it is freezing the humidity out of the ambient air, the evaporator will ice-over and stop working.

38°F-45°F is a very good range to hit - at the evaporator.

After the chilled air flows through the admix plenum, it will pick up latent heat from the heater core and the ducting anyway.

The reason why you cannot get to less than the 'preset-approved temp' is that the whole system freezes up and the passenger's compartment gets warm.

But yeah --- R134a is a urine-poor substitute for R12 or Ammonia.
 

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My current dewpoint here is 10.9° F. ;)

That 30 or 32 degrees I stated earlier is measured with a Weston Mirroband darkroom chemical thermometer stuck in the drivers side dash vent.
 

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Oh ... the old Weston Mirroband, huh? They were usually very accurate in the olden days, but 'way over my payscale.

At least it wasn't an infrared non-contact gun... because generally they can be off by 5° to 20° in the hands of a neophyte.

PS ... how'd you know the dew point? Do you have a sling psychrometer? Kudos!
 

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Discussion Starter · #8 ·
This problem is exactly why I always suggest the "Intelligent Expansion Valve" for R134a.

It is capable of changing the orifice size to compensate for thermal loads - all by itself.

But - no matter - the system can only get as low as the freezing point of water - depending on the local humidity factor, elevation and air density at that moment. 32°F is not usually achievable in an AC system.

The problem is that if it is freezing the humidity out of the ambient air, the evaporator will ice-over and stop working.

38°F-45°F is a very good range to hit - at the evaporator.

After the chilled air flows through the admix plenum, it will pick up latent heat from the heater core and the ducting anyway.

The reason why you cannot get to less than the 'preset-approved temp' is that the whole system freezes up and the passenger's compartment gets warm.

But yeah --- R134a is a urine-poor substitute for R12 or Ammonia.
You are not kidding! I could get snowflakes out of my 1973 Olds! The old torpedo compressers. R-12, I knew her well!
 

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Allowing for a few percentiles of gauge inaccuracy... I can see 34° or 33° F under the circumstances with any refrigerant as long as the atmospherics allow it ... and even though R134a is nowhere as capable as R12 in conveying calories... given higher working pressures and smaller yet more numerous channels with which to transfer heat, it can be close to what I consider the gold standard of refrigeration... ammonia.

I did enjoy working with DuPont 501 (R-22/115 (48.8%:51.2%) though.
 
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