DaleClark

iTrader: (55)

Hey everybody -

As you may or may not know, I finally got an FD weekend before last. Woohoo! Drove it home from Tennessee to Pensacola enjoying the ice cold AC the whole way home.

Well, Tuesday after coming home with the car, one of the guys at work told me he saw a slight puff of smoke coming from the car. Concerned, I went and popped the hood and had a look. Sure enough, every now and then there was a light puff of smoke on the passenger side. Odd part was it wasn't gas, coolant, or oil - I know the smells of those guys VERY well, it really had no smell. I also heard a slight hissing noise - strange!

Anyhow, that night I pulled off some intake pipes and had a good look. The hissing started and stopped as I moved the high pressure AC line - ah! The high pressure line is the "thin" line that's about 1/4" in diameter, the 3/4" or so line is the low pressure line. Anyhow, the high pressure line had rubbed against the metal water pipe that returns coolant from the heater core and wore a hole in the line. Doh! All the freon was gone in no time flat. Found the smoke was from compressor oil that had leaked out and burned off from the heat.

So, I found a good used line to replace it - it got here Monday. I swung by the Mazda dealer with the used line and picked up 2 new o-rings for the line. The o-rings are cheap enough to buy from the local dealer - so cheap they just gave them to me .

That night I went to work. The damaged line wasn't TOO bad to remove - it was the pipe along the passenger side frame rail that has the recharge fitting on it. Using a 17mm and a 19mm wrench, you can break loose the fittings and unscrew them. Had to remove the airbox and the intake to the primary turbo - I could see the fitting I had to remove, but I couldn't physically get the wrench on it. The other end connects at the firewall, and removing the brake booster vacuum line was all that was needed for access.

Installing the new line, I removed the old o-rings that came with the line, put a coat of R-12 compressor oil on the o-rings (you can also use dielectric grease) and re-installed the lines. The fittings just have to be snug, not SUPER tight. You should be able to start threading the compression fitting by hand - if not, you may not have everything lined up straight.

That done, I took the car to a good AC shop yesterday. They pulled a vacuum on the system to remove all the air and any moisture in the system, put 1 pound 4 oz of R-12 in, and sent me on my way. Total cost was $96 for the freon, $20 for the labor. Guys, R-12 is NOT ridiculously expensive - that was a FULL charge on the system too.

End result? The AC will freeze you out of the car. Really, the FD has one of the better AC's all things considered. I totally can't tell that it's on when driving - it makes little to no impact on power. The '90 convertible I've got right now becomes UBER slow with the AC on - it's a HUGE difference running that car with the AC. Even my Lexus SC300 loses a lot of pep off the line with the AC going.

Bottom line - the AC should work VERY well in your car. Do NOT waste your money with R-134a conversions - it will never get nice and cold like it should, and R12 isn't so expensive that it's prohibitive. Most AC work can be done yourself - the most common problem with AC on the RX-7 is leaks, either from compromised lines like I had, or bad o-rings. If nothing else, have an AC shop diagnose what needs to be done to the system (like bad lines, etc.) do the work yourself, and have them pull the system to vacuum and charge.

Dale

Flybye

Thanks for your thoughts, and your insights were pretty good, too

Refilling with R12 (if you are lucky enough to have a few cans lying around) or R134 is not the problem. The problem is the vacuum. It is IMPERATIVE that you pull a vacuum in the system to remove air and moisture. Otherwise the freon will not boil at a low enough temperature causing the AC system to not cool as well as it should.

DaleClark

iTrader: (55)

True. Really, R12 isn't that hard to come by - again, I didn't have any, just took it to a local AC shop and they filled it up. I think they were charging $80 a pound for it - it's expensive, but it's worth it. And, it's not uber-expensive of all the things you can spend money fixing on the car .

The system isn't designed for 134, and 134 just doesn't get that cold. Probably OK if you live up north, where a "hot" day is low 80's with little humidity. Down here in Florida where it hits upper 90's with SERIOUS humidity, we need all the AC we can get . A proper 134 conversion will probably get you 50 degree or so vent temps. Stock R12 setup will get mid-30 degree temps coming out of the vents, with the compressor cycling off as the temp sender in the evaporator cycles as it nears freezing.

Dale