pishta
I know I'm right....
May be helpful for the novice.
EZ reference chart for R134
- Thread starter pishta
- Start date
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May be helpful for the novice.
I have always hated that chart, it can have a novice way overcharge a 134a system. I found this one it is more realistic. And always read the engine rpm that the manufacturer wants you to test for pressure, that is really important.
67Dart273
Well-Known Member
You have to be able to "evaluate" many factors.
1..Do you have enough air over the condenser, "or" what were the conditions under which "the chart(s)" were designed?
2...Like wise, what is the "load in the box" AKA conditions inside the car? Windows open? Temp and humidity "at the load" (inside the passenger compt?)
3....You sure you have enough airflow through the evap, AKA is the blower working properly and on high speed, and or is there any restrictions such as collapsed ducting or plugged filters?
4...Learn to measure and evaluate superheat and subcooling. Superheat has ALWAYS been one of my "go to's" because it is an indication of "protection for the compressor." that is, low superheat means more liquid is "trending" to get back to the compressor.
(Superheat is figured by measuring temp of the suction line as accurately as possible, AKA a temp probe wrapped up in rags/ insulation to avoid effects of engine heat, gives you line temp. Then take suction pressure and read the saturation chart to convert that to temp. Subtract the two and that temp reading is the superhead.} Lower means more liquid= increased danger to slug the compressor. Higher readings means less liquid, but "too high" means under charged, less refrigeration, and also less cooling for the compressor head and valves which is ALSO a danger.
Subcooling if obtained similarly by taking temp of the LIQUID (not the hot gas) line, taking high side pressure and converting that to temp, subtract the two. This gives you and idea of how well the condenser is performing (if it's undersized or dirty or not enough air) and where the charge "sits". Cooler liquid line generally means you have more of charge and of course that has a "grey line" point because as you back up liquid into the condenser, at some point the pressures will rise, and under extreme conditions can then spike because you are headed towards hydro lock
The whole deal is, that there are many things in a system that can lead you down the "rose colored" path, and if you happen to have TWO problems it can really screw up your thinking. ALL of the cars that are typically being worked on here on this board are so old that ANYTHING can or could have happened to the system, including wrong refrigerant or contaminated, as well as a mix of parts
1..Do you have enough air over the condenser, "or" what were the conditions under which "the chart(s)" were designed?
2...Like wise, what is the "load in the box" AKA conditions inside the car? Windows open? Temp and humidity "at the load" (inside the passenger compt?)
3....You sure you have enough airflow through the evap, AKA is the blower working properly and on high speed, and or is there any restrictions such as collapsed ducting or plugged filters?
4...Learn to measure and evaluate superheat and subcooling. Superheat has ALWAYS been one of my "go to's" because it is an indication of "protection for the compressor." that is, low superheat means more liquid is "trending" to get back to the compressor.
(Superheat is figured by measuring temp of the suction line as accurately as possible, AKA a temp probe wrapped up in rags/ insulation to avoid effects of engine heat, gives you line temp. Then take suction pressure and read the saturation chart to convert that to temp. Subtract the two and that temp reading is the superhead.} Lower means more liquid= increased danger to slug the compressor. Higher readings means less liquid, but "too high" means under charged, less refrigeration, and also less cooling for the compressor head and valves which is ALSO a danger.
Subcooling if obtained similarly by taking temp of the LIQUID (not the hot gas) line, taking high side pressure and converting that to temp, subtract the two. This gives you and idea of how well the condenser is performing (if it's undersized or dirty or not enough air) and where the charge "sits". Cooler liquid line generally means you have more of charge and of course that has a "grey line" point because as you back up liquid into the condenser, at some point the pressures will rise, and under extreme conditions can then spike because you are headed towards hydro lock
The whole deal is, that there are many things in a system that can lead you down the "rose colored" path, and if you happen to have TWO problems it can really screw up your thinking. ALL of the cars that are typically being worked on here on this board are so old that ANYTHING can or could have happened to the system, including wrong refrigerant or contaminated, as well as a mix of parts
Interesting.
My row (96-105 at over 40%) says max temp at vent is 61 degrees.
My gauges read OK- 50 and 225-ish, but I have 50-55-ish degrees at the vent.
I do have a condensation issue on the evaporator box, which ends up dripping inside the car..
Should I remove refrigerant? Should I expect the gauge readings to go down?
EDIT- I guess all the way to 36 and 190 would be OK.
...although 50 degrees blowing on me in 98 degree 98% humidity weather feels awful good.
My row (96-105 at over 40%) says max temp at vent is 61 degrees.
My gauges read OK- 50 and 225-ish, but I have 50-55-ish degrees at the vent.
I do have a condensation issue on the evaporator box, which ends up dripping inside the car..
Should I remove refrigerant? Should I expect the gauge readings to go down?
EDIT- I guess all the way to 36 and 190 would be OK.
...although 50 degrees blowing on me in 98 degree 98% humidity weather feels awful good.
pishta
I know I'm right....
Good stuff here! Just dipping my toe into A/C systems, ie, "Husband, you NEED to get my A/C working again or were going to take it to a $$$hop!" Oi veh......I can't jimmy rig this one with my R290 end-around.
pishta
I know I'm right....
What is the normal engine RPM that they suggest, I usually end up reading it at about 1800-2000 RPM That's where this 6-8 speed van cruises.
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