I just want to update this thread, I finally took my car to the shop yesterday to have my AC system looked over. Turns out the problem was that there was air in the system! Well after that was taken care of, the car is happily blowing ice cold AC even when idling for 20 minutes, so there is no need to add any fans on my condenser.

 

My car is going back in on Monday to figure things out. Turns out that the JDM RX-7 uses 17.637 oz of r134a vs the USDM RX-7 which uses 21.2 oz of r134a.

@Akagis_white_comet Pointed the 17.637oz out to me from the JDM RX-7 FSM. This would make sense as I have way less tubing/lines running around. The lines run only on the LH (passenger) side of my car. My hope is that when the refrigerant was filled up last, that the tech researched and found 21.2oz for USDM RX-7. @DaleClark and I are convinced that the system is overcharged and sending my high pressures through the roof. Little known factoid, I used to have ASE certification in automotive AC when I was 20. I haven't messed with it in a long time but still remember it all. It is just a crappy thing that to do it right, you need a recovery machine, which ain't cheap.

I hope to update the thread Monday with the findings. In the meantime, I did a bunch of sealing of gaps that the GReddy VMIC kit has with leftover foam tape from the kit. I think it will make a marked difference in cooling everything (though never had water temps over 85C even in stop and go 100F traffic). Air always takes the path of least resistance.

 

^Air and/or moisture in the system will really make it misbehave! Common problem for guys doing DIY A/C work that results in air getting into the system is forgetting to bleed the yellow charging hose of air when recharging the system with refrigerant.

^Sounds like it's overcharged, especially if the last time it was charged it was done by weight, and they missed the capacity differences between US & JDM specs. If you don't have a recovery machine and a good way to charge it by weight, then next best thing IMO is to charge by what I call the "lowest vent outlet temperature" method. This is NOT the certified HVAC pro way, but it works just about as well in the end, though it takes lots of patience, and is slow. Here's the basic process:

1. Pull a vacuum on the system for a good long time and your starting point will be a completely evacuated system, preferably with a new dryer/receiver.
2. Connect your refrigerant can to the manifold gauge set, bleed the yellow charging hose of air.
3. Charge the 1st can (assumes the usual 14oz R134A cans) as a liquid (can upside down), with the engine/compressor off. The entire can should get pulled into the system which was under vacuum. Let the system sit for at least 15~30 minutes or until the refrigerant static pressures equalize between the low & high sides.
4. Connect the 2nd can to the manifold gauge set, bleed your yellow hose again.
5. Get a thermometer to monitor the air temps coming out of the center vent - an easy to read digital thermo that responds quickly to temp changes would work best here.
6. Consult with the FSM - there's a chart that shows what your high/low side pressures should be at various ambient temperature/humidity conditions. Make note of the ambient temp//humidity you're working with, and consult the chart to get a ballpark idea of where your H/L pressures should be when the system is fully charged.
7. Start the engine, run it at a steady 1500~2000 RPMs and turn on the A/C, you want it on MAX cool, fan on MAX & RECIRC, windows open in the car. Get a helper if necessary to maintain the idle and monitor/report the center outlet air temps to you for the next step.
8. SLOWLY start charging with the second can, by gradually cracking open the charging (low side) valve - compressor will probably be cycling at this point, so you'll want to crack the valve open when you see the low side pressure bottom out, and close it when it rises back up. While you're doing this, keep an eye on the center vent outlet temps - when they look like they are not going to go any lower, stop charging. At this point, your low & high side pressures should be right about where the FSM chart predicted they should be for your current ambient temp & humidity conditions. If you notice the temps going up from where they bottomed out, you're a little overcharged, and you'll have to vent a little bit of refrigerant out.

 

Entirely my fault, I brought it to another shop to replace my compressor while my main guy was on vacation, and this is probably the 2nd time they didn't do a good job...

 

I ordered a 7.5" SPAL Fan and Relay kit. Going to install it and I'll give results.

 

Living in Florida, it gets very hot and humid. My RX7 is r134a (factory). The Greddy VMIC basically makes the condenser a splitter. It doesn’t get as much fan pull as it would have when if it were attached to the radiator as it is in stock form.

I added a SPAL 7.5” pusher fan. As you can see below, there was plenty of real estate to place the fan. It is also only 2” thick and doesn’t make contact with anything.

The fan isn’t any louder than the factory fans when they are running.





I used a SPAL fan relay kit and wired the fan per the instructions.

Yellow to battery 12V with a 30A fuse.

Red to power the fan.

Orange was wired into Cooling Fan relay #1 which is responsible for the fans activating when the AC button is pushed in the cockpit. The wire was matched to the Black/Yellow wire. This provides 12V ignition power.

Gray wire was wired to Cooling Fan Relay #1 as well. This wire was matched with the Violet/Blue wire. This wire provides signal to our new AUX Fan relay. I used heat shrink, spades, etc to make a clean install.

I ran the red and yellow wire along the rear baffle plate shielded with wire insulator.







Here is a shot of the fan in its home from inside the bumper. I used a standard pull through fan mount to mount the fan to the condenser. After I was satisfied it wasn’t moving, I clipped and tightened it down.


Doing a 2000rpm idle test I was getting 37F out of the center vent.

Driving around in stop and go, the AC worked flawlessly. It was 89F outside today. Measured the temp of the asphalt at 125F. I’ll report back more as I get more chances to drive the car. My IAT was ambient and so didn’t appear that the fan impacted any of the airflow over the intercooler.

 

This is great. A 5.2" puller didn't work for me, I should try a pusher fan as an addition. I'm surprised the 7.5" fits! Do you have a link?

 

https://www.summitracing.com/parts/spu-ix-30100393

 

just ordered mine
ac works great if Temps are cool, once it starts heatsoaking it's like a run away train and won't cool I get some air from driving for a bit