Jim eats breakfast at 11:45 AM, in case anyone has wondered. Nice write up Jim.
Harry Watkins Newton, MS 86 SDL Silver 85 300D Euro 86 SDL Gold 81 240D manual trans > Yesterday morning it [AC system] still had a full vacuum on it. > Looking _very_ good! Unfortunately the pressure switch doesn't > seem to work, nor did the spare on the parts car. > > Went to the U-Pull and got the 190E's auxiliary fan and its pressure > switch. Also picked up a headlight assembly, for merging with the one > that's missing a mounting ear. (Cut and glue?) Got the headlight > mount, too, the plastic one below the light, as one of mine is broken. > > I powered up the fan on a battery charger and it worked fine. > However, the fan didn't install too easily because of the damage from > that past wreck. It did eventually go in, and it doesn't even > interfere with the condensor which is a bit of a surprise considering > the condensor's bent-ness. One complication was getting the fan > standoffs (which were also missing) in place: I dropped a sheet metal > screw down between condensor and radiator where it lodged point-in. > Each attempt to pry the two delicate items apart to look for or to try > to retrieve it wedged it in tighter. It didn't seem to penetrate, > however, and I was eventually able to fish it out with a magnet. I > had to pull the headlight to route the wire, and it seems to me I > should have gotten the headlight mount plastic top bits as well. > Sigh. > > The pressure switch installed easily, and works properly. That, at > least, is a relief. Using compressed air I got the other two switches > responding, but I wouldn't use them except in an emergency. (Or at > all if it cost more than $7 to charge the AC system.) > > Today... > > The AC held pressure overnight, so I started it up. What a drag, the > auxiliary fan runs all the time and the compressor not at all. Time > to dive in! The drier's switches for compressor and fan both seem OK. > Off to the manuals, I guess. There are relays involved in both > functions, it's not as simple as the circuitry in earlier cars. Using > the ETM I tracked down the fan temperature sensor and unplugged it. > The fan stopped. Great, a bad sensor. I took a small hammer and > tapped on the sensor body with it reconnected and the fan shut off. > I've seen this before, sometimes it's enough just to do that, the > sensor is merely stuck and will behave itself in future. We'll see. > > I used a jumper to short out both the engine temperature sensor and > the drier overtemperature switch. The former runs the auxiliary fan > at high speed, the latter, low. Good. The fan system seems to be OK > now, modulo that sticky sensor. > > Nah, that sensor's no good. Its other contact turns off the AC > compressor, and it's stuck too. Unplugging it resulted in the > compressor running normally. Banging on the sensor did nothing to > relieve this problem. I have a spare sensor that I'd bought for > my wife's 560 SL last year, which developed a stuck fan contact, > but that problem cleared itself up before I could install the new > sensor. It's been sitting on a shelf since, I'll probably put it in > this car. The full-throttle switch atop the intake manifold also > works to shut off the AC compressor, as it should. > > While doing this testing I noticed a large fuel leak out of the > injector return line between #'s 2-3. That's new. I pulled it off > and replaced it with new line. > > I started putting in a test charge of refrigerant. It fills slowly, > perhaps because it's not too warm out yet today, or perhaps because > there is a restriction in the low-side valving. (I've seen that > before.) But I was able to get a fair amount of test refrigerant in > there and I was starting to get reasonable pressures. Unfortunately > my vent temperatures never got very low, and I thought I even detected > some heat coming out the center vent. The sight glass showed plenty > of refrigerant flow. (Very foamy, as is normal for this refrigerant.) > So I pulled the access panels to the water valve and had a look. It's > not always shut off properly. I don't know if it's a control problem > or a vacuum leak problem, this will bear some looking into. I > manually pulled the valve shut, and then I could feel the vacuum > system kick in, but that never really changed anything at the vents. > The water pipe remained pretty hot. I wonder if the water valve > leaks? (I know it can take awhile to pull the heat out of the heater > core at summer temperatures.) Gotta dive into that too. > > Only one of the horns works. Shoulda grabbed that horn bar at the > U-Pull! Maybe I'll go back to get the horns, and have a look for > water valves, etc. Must remember to grab the headlight mounting > plastic bits too. Time for breakfast again! > > -- Jim
