Greetings from the Valley of the Sun!
Warning: This message may self destruct from the repugnant heat and
excessive sunlight shortly after viewing.
Some of you may recall that I purchased an '86 300E back in December last
year. Over the past few months I've been curing some minor ills it had at
purchase time. To review; I've replaced the fuel injectors, O2 sensor, fuel
tank sending unit, flex fuel hose (pump pressure side), right inner tierod,
cruise control module, windshield, radiator expansion tank, valve cover
gasket, spark plugs, fan clutch, plus all the necessary adjustments, filter
and fluid changes. Additionally, I had the A/C recharged with some R12 at a
local shop and recently removed the blower fan motor and cleaned the
noticeably plugged evaporator. This leads me to the issue at hand. Let me
preface it with a reminder of the daytime temperatures here in Phoenix
(113-116 degrees F).
That said, on to the problem. Directly after the R12 was added to the
system, I've been experiencing compressor "cut out" at idle or in traffic.
I'm surmising it's because the head pressure is too high and the switch is
doing it's job. Though I ask myself and you all; why? What is causing the
compressor to "cut out" in traffic or while stopped? If I turn off the A/C
in traffic and wait until I'm moving again to turn it back on, it performs
normally. When the compressor cuts out, it will not come back on until the
engine is turned off and restarted. If I do this in traffic, the compressor
repeats the "cut out", if I do this at the on ramp to the highway, it
remains on. During all of this, the engine temperature remains at about
85-90 degrees C and does not fluctuate greatly. Recently, I drove from
Phoenix to Denver and back (1922 miles) and had no problems with the A/C
with one exception which I'll mention later.
Being a man of reason, I'm thinking I may have two problems; one being the
fan switch, which is mounted on the "high side" is inoperative. I have
shorted the two wires from this switch to run the fan at all times. If the
fan is off in this heat, the compressor "cut out" problem increases it's
frequency. The problem does seem to be mildly better (less frequent cut
outs) since I cleaned the evaporator. The second probable cause could be
the engine "under cover" which is missing. I believe this is allowing the
reflective heat (145 degrees F) from the asphalt to mix with the incoming
air across the condenser, thus exacerbating the problem with an influx of
heated air. I'm now on the prowl for an engine "under cover" in hopes this
will add another mend to the process. Any thoughts to this complicated
issue would be greatly appreciated.
Another concern I have is the vents. I have no center vent air volume, only
the side, floor and defrost vents. This I believe to be the vacuum servos,
but I'm not sure as I haven't delved into the "under dash" area of this car.
Only a short time ago (before the heat arrived) I used to hear one of the
plenum doors slam shut or open (whichever the case) a few seconds after
starting the vehicle. This noise has stopped. Another noise that comes and
goes is a "whistling" sound coming from the glove box area as soon as the
key is turned on. The engine doesn't have to be running and the climate
control can be either off or on. If the ignition key is turned on and back
off, then on again, the "whistle" will sometimes go away. It does however
always go away after a short run time, say from the driveway to the street
corner. Come to think of it though, the "whistling" has disappeared
recently. Possibly because I cleaned the evaporator? I don't know. Anyone
versed in the air distribution of this W124 that can offer some assistance
would be greatly appreciated.
Thank you for your time it took to read this and thank you in advance for
"The best, the most exquisite automobile is a walking stick;
and one of the finest things in life is going on a journey with it"
~ Robert Coates Holliday