no mufflers
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yes you are correct. I just had the motor out so the a/c system was empty and at that point I replaced all the old r12 parts with new 134a parts.
A/C questions
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junk
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I would match the freon charge to the compressor you're using. So if you're using a 97 compressor I'd match the freon charge to a 97 truck which I'm guessing was R134A to begin with.
The V-belt compressors are different than the serpentine drive systems. And that also seems to coorelate to the amount of freon. Older V-belt systems take more freon. Early serpentine r-12 systems take less freon and then when they went R-134 they take even less freon.
I've always assumed the compressor was what determined refrigerant volume.
Around 1994 or so they switched the componenets from standard thread to metric thread. So did you switch out all you're hoses and components to the newer metric style? What did you do for a compressor?
Not sure what to tell ya.
The V-belt compressors are different than the serpentine drive systems. And that also seems to coorelate to the amount of freon. Older V-belt systems take more freon. Early serpentine r-12 systems take less freon and then when they went R-134 they take even less freon.
I've always assumed the compressor was what determined refrigerant volume.
Around 1994 or so they switched the componenets from standard thread to metric thread. So did you switch out all you're hoses and components to the newer metric style? What did you do for a compressor?
Not sure what to tell ya.
no mufflers
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the 2.38 lbs is what 97 year calls for.
the compressor, condenser, evap, drier and line from evap to condenser are from a 1997 f250 diesel truck.
the line from drier to compressor is from a 1994 IDI truck. it uses the same manifold design just a longer line because the compressor is lower on an IDI.
the thing that bugs me is it was colder with the old parts and 134a then with all new parts and same 134a.
the compressor, condenser, evap, drier and line from evap to condenser are from a 1997 f250 diesel truck.
the line from drier to compressor is from a 1994 IDI truck. it uses the same manifold design just a longer line because the compressor is lower on an IDI.
the thing that bugs me is it was colder with the old parts and 134a then with all new parts and same 134a.
junk
Full Access Member
Did you replace the pressure switch on the drier or adjust the pressure switch when you switched parts? I'm wondering if an R-12 pressure switch with R-134 components is causing issues.
Good luck.
Good luck.
no mufflers
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it is a new one for 134a. I have not adjusted it yet. I guess it might need to be.
gnathv
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That pressure switch on accumulator only controls clutch cycling which prevents freezing up evaporator. Is your clutch kicking out before it's cooling? If so you need to lower switch pressure. If in doubt, jumper it and make compressor run continuously and see if it cools.
no mufflers
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I have been running the fan on m1 and the clutch stays on all the time, I have tried m2 but doesn't make the air any colder just more volume of air.
gnathv
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What is the lowest pressure you see on your low side? If you slightly increase rpms does it lessen or stay the same?
gnathv
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Your coldest temp will be on lowest fan, less air across evaporator moving slower.
no mufflers
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the low side was around 30 psi on high idle. I didn't try to rev it up more. I have been leaving it on m1 because lo barely moves any air.
gnathv
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At a pressure of 30psi you should see 34.6 degrees on the evaporator. I'm seeing under 8500 gvw 33oz and over 8500 gvw 38oz. I have a 97 and 3 cans (12oz) is about right. Are you pretty sure there's not excessive oil in it. Something's preventing your evaporator from proper saturation.
no mufflers
Full Access Member
Most of the parts are new so it might not really have much oil in it at all. The machine should have put in 4 oz of oil. Do I need more? The compressor already had some oil in it. That is why I'm wondering if I need a different orifice tube. Or would the pressures not match up?
If it was a new compressor it probably wasn't the right type of oil it was shipped with. The system according to the source I found said 7 oz of oil. Should put about half in the compressor and distribute the rest. If you don't know how much oil is in the system, it might pay you to flush it and start over. Just turn the compressor up and drain it by rotating it slowly standing on end. Seems like too much oil or a plugged orifice tube might be causing your problem. Something isn't right. If it were me, I'd pull it down, flush it and start over so that I was sure what was in there.
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all parts effect the amount of refrigerant needed. But the compressor is neglagable. The condenser and evaporator are the 2 parts that effect the amount more than any others
no mufflers
Full Access Member
thanks for the info guys.
ill suck it down and check out the orifice tube, maybe something got in it. then I might check out the compressor for oil.
I do have a blue orifice tube, should I give that one try? I know there different sizes but not sure of the specs on them.
ill suck it down and check out the orifice tube, maybe something got in it. then I might check out the compressor for oil.
I do have a blue orifice tube, should I give that one try? I know there different sizes but not sure of the specs on them.
