Tuesday, August 30, 2011

The A/C Lines Are Installed

I confess, I expected that getting the A/C lines made to hook up to this compressor was going to be a challenge.  You could even say I was pessimistic about the whole affair.  I just couldn't envision how these lines could be made to fit in place, tie seamlessly into the car's existing system and hold pressure.  For a while it looked as if my doubts were justified. 

When I got the hoses back toward the end of last week, the technician handed them to me and began to explain how I should hook them up.  He said I should hook both ends up first, and then tighten the compression fitting in the middle.  I felt a wave of panic when he said "compression fitting."  You see, I hate compression fittings.  Despise them.  If there's a hell, it's occupied by the man that invented them and everyone else who is there is forever forced to try and make them work.  It's been my experience that compression fittings work absolutely fine, until you try to put anything in the hose they are on under pressure.  Then they proceed to leak everywhere, and nothing you do can makes them work. 

I hooked up the long, low pressure line that runs from the evaporator to the compressor, and began carefully tightening the compression fittings.  For those of you unfamiliar with how to tighten them, you are supposed to tighten them hand tight and then give the nut another 1/2 turn or so.  If you under tighten it, it leaks.  If you over tighten it, it leaks and you've ruined the ferrule inside and must replace it or the whole thing.  With that in mind, I followed the rules: hand tight, but then I did about a 1/4 turn.  I did a pressure test and it leaked like mad.  OK, 1/4 more of a turn and another pressure test.  More leaking.  *Sigh*  1/4 more of a turn and it's leaking worse than ever.  Undo the whole thing, check for dirt, debris or any other problems.  It all seems fine, so try it again. 

This went on for 3 hours or so.  It began to become difficult working through the tears of anger and frustration.  Eventually I had to resign myself to the fact that it simply wasn't going to work.  Oddly, the second hose, the high pressure side, seemed to work just fine.  Now I say that having not had the system charged.  I fully expect that when I take it down to have the shop draw a vacuum on it, and then charge it up, they're going to tell me it leaks from that joint.  I sure hope not, but if one of them is going to leak, that's the one that I can deal with.  I can reach it and remove it without dis-assembling the car.  The low pressure side requires I remove the larger battery rack under the hood to access it. 

I took it back to the shop today and explained my problem.  One of the guys, who's clearly been in this game for a while, looked at it and said, "Yeah, that will never seal.  It needs to be brazed."  That was music to my ears.  He said give us a few minutes and we'll take care of it.  They brazed a nut fitting on the aluminum tube and crimped it's male counter part on the existing hose.  I was a little irritated that I'd spent all that time on a fitting that clearly the expert felt was the wrong part for the job.  But I was so happy that it now had the right joint, I wasn't about to complain. 

I took the parts back home and began hooking them up.  It took a couple hours and I got the new dryer/receiver in place, both new hoses, the compressor mounted and the new lines attached to the compressor.  It looks terrific, but I have no way of pressure testing it apart from adding coolant to the system, which I'm not going to do until I know it won't leak.  Once the rest of the car is assembled, I'll drive it down to a local shop and they'll do all that for me.

I put together another quick (and very rough) video of what was accomplished today.  Take a look...

Another component to this is the controls for the A/C system.  They consist of an On/Off switch and a potentiometer that acts as the thermostat.  MasterFlux sells a little black box that incorporates both of those items, but I can't imagine using that in the car because it's simply hideous.  They say it's mostly for testing, and I can believe that.  I picked one up in case I needed it, but I don't think I will, so it's going back.  Instead, MasterFlux publish the specs on the device complete with part numbers and how to wire it.  I found the very same potentiometer online and bought it.  The great thing was they also had a variety of knobs to choose from to mount on the potentiometer's shaft, as well as the molex connector needed to plug all the wires into the controller board.  For the On/Off switch I'll be using the original A/C On/Off switch that came with the car.  Here's how the whole thing came out.

 Down low on the center console, just the right of the gear shift is the little silver knob that will be the temperature control for the system.  I really could think of no way to incorporate that functionality into the car's original thermostat dial above.  You see that dial just moves different baffles to control the direction of air flow, either over the A/C system's evaporator, or over the heating core.  There's no way to hook any electrical component up it.  At least no way I was willing to try.  I think that little knob will do just fine.  The On/Off switch is the top button in that two button module directly to the right of the new Link-Pro meter.

Lastly, you may recall that I was having problems keeping the Zilla controller cool in the desert heat.  I think part of the problem was the fact that I was using a radiator that was only 4"x8" in size.  Well in the video above, you saw that the new radiator is about 3 times that size.  Hopefully it will keep things a bit cooler.  But it also has a nice big fan to help suck air through it.  Well, I didn't see any point to having that fan run all the time.  After all, when I'm sitting idle in traffic, there's no heat generated in the Zilla, or when I'm cruising down the road at 40 MPH drawing only 60 amps, the air moving through the radiator is more than adequate to cool the controller. 

What I need is some way to monitor the temperature of the controller and turn the fan on when it starts to get too warm.  I started looking and found what I think would work.  It's a switch that will close a contact when it hits 122 °F.  It opens up again at around 115°.  That is well below the point the Zilla begins to complain about heat, but high enough that the fan won't run unnecessarily.  The switch itself is just a little button style switch that has to be in contact with the item you're monitoring.  The place I've noticed seems to get hottest on the Zilla is the top, right in the center.  It may get hotter else where, but I don't have access to where ever that might be.  So the question became, how do I mount a small dime-sized switch to the top of the Zilla without it moving around or looking too hideous.  Here's what I came up with, you be the judge...

That piece of aluminum is pressed and held down tight to the top of the controller.  The switch is held down tight to the aluminum strip.  I used some thermal paste left over from my last CPU purchase to help heat conduct into the switch.  The switch drives the relay you see at the bottom of the screen, which will then turn the fan for the radiator on.  OK, it might not be the sexiest of solutions, but I thought it was pretty clever and should do the trick nicely. 

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