Just a point in time.

Miata A/C Evaporator Replacement

It's been at least a year since the A/C in the '94 Miata blew cold. It just gradually faded out so I didn't really notice for a long time, until I realized it was really damn hot in the car all the time. I thought for a while that I was going to have to take it to an A/C repair shop, which really goes against my grain. I also knew it would be expensive. At some point, though, I had a revelation. That revelation told me that fixing the A/C was no different from fixing anything else. All I needed was the right tools. A quick check online showed me that spare parts for my '94's A/C system were pretty cheap. I wanted to do it right so I needed the proper tools - a manifold set and a vacuum pump. I already had the manifold set from a previous effort at diagnosing an A/C problem in my old truck, and an appropriate vacuum pump can be purchased at Harbor Freight for around a hundred bucks, which I did.

I'll skip over how I diagnosed the problem, but suffice to say I figured out the problem was the expansion valve. When I went to order a new one for $25, I found that a new evaporator core was only $50, so I ordered one of those, too, just for good measure. Finally, because everyone says you should, I ordered a new receiver/dryer for about $15 and a bag full of o-rings for $3.
This post isn't meant to be a detailed how-to, but it is a "you can". This job was dead easy, except for crawling up under the dash to yank the old evaporator core out. I used this tutorial to guide my actions and it was very applicable to my Miata. The evaporator core is housed in a black plastic box, bolted to the firewall right behind the glove box, with two small 10mm nuts. On the right, it connects to the blower housing. On the left, the center air control unit. Two aluminum pipes stick out through two holes in the firewall, where they connect to some more pipes that go to the compressor and the condensor. I didn't need to mess with either of those things. I disconnected those pipes, unbolted the box, released the clamps that connect the box to the left and the right, and yanked. With a little persuasion, being careful not to damage any aluminum bits, it came out. The evaporator box is held shut with some metal clips that pop right off with a screwdriver, and two screws. The whole thing clams open and you can pull the core right out.

The old and new evap assemblies. After I assembled the expansion valve to the core.

Here's the old core.

Here's the new core with the expansion valve all connected up, set into the lower half of the box. There's a temperature probe that is wrapped to the big tube.  Ok, actually, I don't know what the hell that does. I just connected it up like the old one.

Here's the whole evaporator assembly ready to go back in.  I just had to be careful sticking those aluminum tubes through the firewall, not to jack up the threads.

Here are the connection points just ahead of the firewall in the engine compartment.  They were misaligned quite badly and took some persuasion to get threaded.  Then I initially forgot to tighten the big one down all the way, which became apparent later when I tried to put a vacuum on the system.

Ahh sweet vacuum.  This is what you want to see when you run the vacuum pump. The inside numbers read vacuum in units of inHg (inches of mercury). You run it for about 5 minutes at first. Then you want to stop the pump and wait 10 minutes and hopefully your vacuum doesn't go away. If it does, there's a leak somewhere. I had a big one, but it was easy to find and fix. Then I let the pump run for a good half-hour.

Hard to get it all in the picture but this is how the vacuum pump is hooked up. The blue line is the low pressure side, the red is high, and the yellow line is the line through which you apply vacuum, or feed refrigerant.

Here's where my running pressures ended up after adding 22 ounces of refrigerant and two ounces of oil to the system (I'm banking on there being some old oil left in there). I wanted to see more like 200 psi on the high side, so I may need to add some more R134a, or possibly my compressor isn't strong. We'll see how it cools over the next few days. It felt pretty cold just running it in the garage.

So to sum up, this was an easy project that should make my '94 a lot more comfortable in the Florida summer, which is fast approaching. I commute almost two hours every day now, so having this A/C working is going to be pretty important.

Another iPhone HDR photo

Ninja 250R

M3 HDR photo

I bought a great HDR photography app for the iPhone. It lets you really tweak the photo after you take it. It doesn't just simulate HDR, it really takes two photos and melds them together.
Nothing significant about this photo other than playing with the HDR app.

Iggee leatherette seatcovers - installation in the '94 Miata

Did this today. They are Iggee leatherette (vinyl) seat covers - not full upholstery. They install over the existing cloth seats. Got them directly from Iggee through eBay for $125. Will just show the driver side.

The driver seat is getting a bit tatty.

The bottom cover is held tight by six elastic straps that hook on the bottom of the seat pan. Then a drawstring-like cord ties in the back. I routed it through a hole in the seat pan. This photo is before I was quite done tying things up.

The back cover is held tight by these big velcro flaps. Installation is an exercise in trying to pull them tight from both sides while sticking the velcro.

Pretty much done.

Back in the car.

For a slipcover, these are amazingly nice. You can tell they're slipcovers if you're looking for it, but when sitting in the car it's just like the seats were meant to be that way. No more tatty seats!

Brego got a new windshield today.

Brego the 2002 Boxster S got smacked by a rock on the road a couple weeks ago. It started off as about a 1-inch crack and the insurance company agreed to pay for a repair. The repair attempt failed, though, and before the technician was even done with his work the crack had grown to several inches long. So, the insurance company agreed to replace the windshield, and waived the deductible (nice!). They had to order one of the moldings around the windshield so it took a few days for them to get out here to do it. The result is fantastic! No more scratched and pitted windshield, and no more big crack!

Hardtop Finished

I have absolutely zero patience so today, rather than wait the recommended 48 hours, I went ahead and wet sanded and buffed the hardtop. I used a rubber sanding block with a spray bottle to keep the surface wet. Starting with 1000 grit, at first the sandpaper grabs the surface and it takes a little push to keep it going, even with lots of water. After a few passes, the surface really smooths out and the sandpaper starts to glide effortlessly over the surface. I put very little downward pressure on the sanding block. After the 2000 grit, the surface was smooth as a baby's bottom, but not glossy. When it is uniformly hazed, it's ready to polish.

For polishing I used my Griot's Garage random orbital polisher with Griot's Machine Polish #2 followed by Machine Polish #3. This brings the 2000-grit sanded surface to a high gloss in just a couple passes. This photo shows nicely the difference between the sanded and polished surfaces.

This photo shows half the top polished and the other half after wet sanding. I went over it once with #2 polish and once or twice with #3. I was nervous about breaking through the clear and getting into the base color, because I just don't have a good feel for how much clear you should spray and how much you can sand and polish off before you go too far.

There was a bit of very fine orange peel that got a lot better but didn't completely sand out. I really didn't think I'd be able to polish it out and I was right. It's visible. I can certainly go back and sand it some more and maybe at some point I'll do that. It came up nice and glossy, though, so I'm pretty happy with it. It looks better than the red paint on the rest of the car.

Here's the car with the top on it. It would be better in red but I am sure that if I'd painted the top red it would not come close to matching the old red paint on the car and I don't have the expertise to tweak it.

I took the car for a drive on the highway and on some local backroads and the difference is amazing. I've had a hardtop before but it's been a few years. The car is definitely quieter. I swear that I can also feel the weight of the hardtop. It's an additional 45 pounds at the highest point in the car so it will, in theory, make the car sway a bit more in turns and be a little more sluggish in transitions. I've been driving this car for 14 years now so I can feel even subtle changes in how it handles and I do feel this. My plan is to remove the soft top completely so that should offset some of the weight gained with the hard top.

Hardtop progress

So here is the hardtop after a couple coats of black paint. (See the prep article a couple posts down.) Doesn't look good yet. I had originally bought some Mazda paint code PZ Brilliant Black paint online, but much to my chagrin, one can of it was not enough to cover the top. I ended up going to Pep Boyz and buying a couple cans of Duplicolor universal black and two cans of their clear coat as well. I did a quick wet-sand with 600 grit paper of the black base I had already put down and then put down 3 more coats of color.

And here it is with about 3 more coats of black on it and three coats of clear. It's somewhat glossy, but is not going to come to full fruition until I wet sand and buff it. But I think it's going to end up looking just fine. Not bad for a $30 rattle can job. By the time this is over I will probably have 10 or 12 hours of labor in it, but this is a hobby for me and the time spent is not lost.

HERE is the third post about painting my hardtop.

Installed

Here's what the smoked parking light looks like installed. I really like it. It's a nice update to the Miata's 20 year old styling, and not too ricey or cheap looking. The lights themselves are exact copies of the factory lights. Perhaps the plastic is a tiny bit thinner, but every detail of the fixture is identical to my eye - with the exception of the lens and reflector, of course. They even came with new mounting screws, wiring harnesses, and light bulbs. We'll see if they fill up with water or melt or something.