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Restomodair Upgraded AC

So, I replaced the compressor, dryer, evaporator, and expansion valve with all new ones. I also fabricated all new hoses and updated the condenser to a parallel flow type. Using Duracool, I got 50 at the vents on a 100 degree day driving from Atlanta to Savannah (around 4 hours).

I’m pretty happy with that. At some point I’d like to switch to the accumulator and orifice tube style setup from the 91-93 models, mostly because the evaporator appears to be a much more efficient design.

Thanks for all the help. If/when the blower goes I’ll be switching to the Classic Auto Air setup. May as well if I’ve got to tear the dash apart anyway.
 
This was shared with me by a 1990 740 owner who contacted me about AC and other stuff.

Thought I would pass this on to those of you with later orifice tube AC systems. I know little about orifice tubes, so I can't help with this tech, but some of you may know more.
Dave B

I got great results from R-134a with massive airflow across the condenser (dual fans) and using an adjustable low-pressure shut-off switch to lower temperature at the evaporator (lower P -> lower T). Occasionally, I have to turn off the compressor for de-icing... However, when it's 100? outside in S Texas, blowing 35? air inside the car at high fan speed makes up for the inconvenience.

It appears to be a 4 Seasons item
https://www.ebay.com/itm/A-C-Clutch-Cycle-Switch-Pressure-Switch-4-Seasons-35751/332154143873
pre-set at 47/28 psi on/off.

The switch and A/C tuning were done in Nov 2012 by John Noble who owns https://coolflowindustries.net/ in Houston.
John adjusted the switch to somewhere around 20 psi off ("warranty void if adjusted" LOL), judging by lowest air outlet temps I have seen.

For yr amusement, saturation T/P chart for R134 is attached (BELOW).
Assuming that any liquid is squirting into the evap coil, this would be temperature of the gas, at various pressures. Simple (my favorite) thermodynamics.
Click to expand...
 

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And here's an explanation of that switch from the Volvo Greenbook.

Dave B
 

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