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Car Forum / Porsche / Porshe 944 / June 2008hum / buzz (electronic?) from passenger dash area
'87 944 n.a. -- need help identifying origin of electrical noise. symptom : there's an electrical-ish sounding hum / buzz apparently behind the dash on the passenger side that is constant while the electrical system is engaged (i.e. when the key is at stage I) and persists after the engine is operating. it varies little if at all. once i started hearing it, i have failed to hear it "disappear". observations : seems not to be localized at cigarette lighter, but its close. the ventilation system seems OK i.e. temperature/fan/ defrost works. glove box light connection is "dirty", but sound is not there. clock is backlit but not working. not sure what to say about A.C. haz. lights work. i looked thru Porsche's parts catalog for 1987-1991 944's, esp. sec. 9.901. i am stuck. any questions/ pointers appreciated. btw, Porsche has another catalog for 944's, but for 1985-1988 -- is the overlap redunant? -bryan The heater fan runs at all times when the ignition is on. There is no off position. Alec > '87 944 n.a. -- need help identifying origin of electrical noise. > [quoted text clipped - 16 lines] > > -bryan there is a small motor that sucks air in over a sensor to control interior temperature - the bearings get dry after 20 years - motor is located above glove box near center of car - it's connected to the tube that goes to the small round grill - you should probably remove it, oil bearings and put it back as a precaution, but that may well be where the buzz is coming from. Heater fan is in the engine compartment on other side of firewall as an aside, I have a spare heater fan motor that is good, if you need it, and I have a spare one of these little motors too > '87 944 n.a. -- need help identifying origin of electrical noise. > [quoted text clipped - 16 lines] > > -bryan ** Posted from http://www.teranews.com ** > there is a small motor that sucks air in over a sensor to control interior > temperature - the bearings get dry after 20 years - motor is located above > glove box near center of car can the motor be accessed by removing only the glove compartment? i.e. without removing the entire dash? -bryan yes, pull the golve box liner, like on your back and look up - follow the tube from teh circular grill and the motor is at the other end. clean and lube it and at least one source of noise is fixed >> there is a small motor that sucks air in over a sensor to control >> interior [quoted text clipped - 6 lines] > > -bryan ** Posted from http://www.teranews.com ** > yes, pull the golve box liner, like on your back and look up - follow the > tube from teh circular grill and the motor is at the other end. cool, i see it! so simply detach all wires/bolts and pull it out? -- i.e. are there any particular connections that are tricky? i see some solder points on it, not sure where they lead to - do i need a solder iron? -bryan do NOT unsolder anything - there is a plug that connects to it, one (or two?) screws, and the hose - remove it, oil the bearings and put it back. Be careful, the thermistor is delicate. On May 18, 7:54 pm, "William Noble" <nob...@nowhere.com> wrote: > yes, pull the golve box liner, like on your back and look up - follow the > tube from teh circular grill and the motor is at the other end. cool, i see it! so simply detach all wires/bolts and pull it out? -- i.e. are there any particular connections that are tricky? i see some solder points on it, not sure where they lead to - do i need a solder iron? -bryan ** Posted from http://www.teranews.com ** > do NOT unsolder anything - there is a plug that connects to it, one (or > two?) screws, two screws. the unit reads "Bosch APK 12V 0 130 002 808 [058]". > and the hose - remove it, oil the bearings and put it back. ok, i air-dusted it, removed the thermistor wire clip, and the motor cap, has rubber piece inside protecting the motor and wires. the turbine rotates by hand without making any obvious sounds, and seems slightly resistant to manually moving it. i plugged it back in, makes a reasonable electric motor buzz, i.e. nothing awful, but i suspect it will not be silent esp. when on a bracket to transmit the vibrations. but what am i looking for? the actual electric motor part is rather secure in there, and i can't identify any bearings - i figure i could blow some graphite lube up directly into and inside the actual metal electromagnetic motor, or spray some non-petroleum silione lube, but frankly i don't know what that'll all do to it. i also found some Elmers lube which doesn't identify any of the materials in it. i have some 3-in-1... but where specifically does the motor take such lube? i don't want to contaminate the electromagnet parts.. > Be careful, the thermistor is delicate. looks so... -bryan On Jun 19, 12:45 am, "William Noble" <nob...@nowhere.com> wrote: > do NOT unsolder anything - there is a plug that connects to it, one (or > two?) screws, two screws. the unit reads "Bosch APK 12V 0 130 002 808 [058]". > and the hose - remove it, oil the bearings and put it back. ok, i air-dusted it, removed the thermistor wire clip, and the motor cap, has rubber piece inside protecting the motor and wires. the turbine rotates by hand without making any obvious sounds, and seems slightly resistant to manually moving it. i plugged it back in, makes a reasonable electric motor buzz, i.e. nothing awful, but i suspect it will not be silent esp. when on a bracket to transmit the vibrations. but what am i looking for? the actual electric motor part is rather secure in there, and i can't identify any bearings - i figure i could blow some graphite lube up directly into and inside the actual metal electromagnetic motor, or spray some non-petroleum silione lube, but frankly i don't know what that'll all do to it. i also found some Elmers lube which doesn't identify any of the materials in it. i have some 3-in-1... but where specifically does the motor take such lube? i don't want to contaminate the electromagnet parts.. > Be careful, the thermistor is delicate. looks so... -bryan please don't destroy your sensor - The bearings are at either end of the motor armature. they are phosphor bronze. Add some high grade oil (NOT 3 in 1 oil) to each bearing, just a couple of drops, and re-install. Do not go blowing unknown crap into the motor, that's just asking for problems. place the oil exactly on each bearing. ** Posted from http://www.teranews.com ** > Add some high grade oil (NOT 3 in 1 oil) to each bearing, just a > couple of drops, and re-install. what compounds would "high grade" be identified/not identified with? any brand name? i just browsed thru Home Depot and nothing seems right - maybe a model/crafts store? -bryan I use "clock oil", which not surprisingly I got from a clock repair supply place, but you could use Starrett Instrument oil, Shell Tellus 10 wt oil, any good instrument oil - I'm not sure that Quality Oil and Home Depot really can be said in the same sentence - try a machinery supply place, or an instrument/electronic repair place - you can get a syringe type oil dispenser with good quality oil in it for $10 or so On Jun 23, 1:13 am, "William Noble" <nob...@nowhere.com> wrote: > Add some high grade oil (NOT 3 in 1 oil) to each bearing, just a > couple of drops, and re-install. what compounds would "high grade" be identified/not identified with? any brand name? i just browsed thru Home Depot and nothing seems right - maybe a model/crafts store? -bryan ** Posted from http://www.teranews.com ** |
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