2015 has been the hottest year around the planet, so I hear.

I wanted to improve the cooling of the front cabin in my 1997, so I cut two vent openings at the roof ducting and finisher panel where there are 3 a/c vents for the rear passengers.

the result is that if I close two or all three of the rear vents, the air is forced to the front cabin, making for nicer air conditioning.

the job isn't finished yet, I want to improve the modification. But so far, the idea has worked great.

 

Wow, that's pretty bad when you need both systems just to cool the front. Are you sure your system is working at its peak performance? You realize that when you turn on the rear unit, it takes a significant amount of the coolant from the front section?

When I do that on mine, I can usually see the temperature of the air coming out the front vents go up by a few degrees. So for me, the best way to keep the front cabin cool is to use just the front unit, but crank it up.

 

the outside temp is Florida is horrendous, so every little bit helps.

yes I have noticed the coolant level change when using the rear HEATER, but not the a/c.

 

Do you have a dual system with two evaporators or just ducting from the front unit to the rear?

 

Good idea.
Aero needs the rear evap operating because neither has great heat transfer.
Also, roof insulation, duct sealing, dynamic orifice, ES12.

 

Rojostar,
ES12 ? cools better than R134a ??

 

I have no formal analysis and not a whole lot of road time in Florida.
My '89 system was designed to R12 and was never happy with the 134 conversion.
I dropped in about 4 oz ES12 (equivalent to 12oz R12, according to the company) along side an existing 134 charge and it seemed to get happier.

 

I'm using Enviro-Safe as well; installed it in 2009 when I overhauled my AC. It's been working great since then; at full capacity, it will push out air at 50F from just the front, and about 55 with the rear on.

I considered the R-134 conversion, but I read that it was not as efficient as R-12 as a refrigerant. Using the same hardware on R-134 would not achieve same cooling power as with R-12, or a drop-in replacement. So I went with the drop-in replacement.

I am intrigued by the dynamic orifice tube. Is it supposed to maintain evaporation efficiency at different pressures and/or flow rates?

 

I believe you are spot on, but I'm again caught out on specifics.
It also (probably) reduces the work the compressor has to do.

aka Variable Orifice Valve (VOV).

It took a try or two to come up with the proper style, front and back. Hence the pic above, out of my photo library, might be showing original, correct vov and incorrect vov. It's been awhile. Caveat emptor, do your own homework.

 

Here's a good explanation of variable orifice valve:

Fixed and Variable Orifice Tube Difference

It's suppose to improve performance when there is low air flow through the condenser, and gaseous refrigerant, which is not effective at cooling, gets to the evaporator. In those conditions, it reduces the effective size of the orifice, thus reducing the refrigerant flow rate (and increasing the pressure), forcing the refrigerant to spend more time in the condenser, and forcing more of it to liquify before leaving the condenser.

 

my '97 has two separate a/c and heater systems, I can use the rear system or the front, individually or together.

in other words, the rear system is independent from the front, sharing only the compressor, condenser, and accumulator.

Today the modification proved itself, it is really cooling the front cabin to my liking.

 

I found the Enviro Safe website and I am going to try their refrigerant in my Jaguar XJ-6 which is stll R12 and I do not want R134a.
.

 

Not having a rear headliner must be a major factor down there!

 

I took it down to redo the fabric. it's only temporary.