PhilbertZ Posted May 12, 2008 Share Posted May 12, 2008 Hi guys, I think I had asked this in another thread but it got overlooked so I'm starting a new one on the topic. My car, when I have the climate control on (the fan is switched on - either low, or medium setting), sometimes sends the interior blower fans into a tizzy at random. It happens, like I said at random, and I can't tie it to one action on my part (putting the gas on, cold engine, etc) - it just happens when it happens. It's as if the blower fan is cranked up to 100% at random for a few seconds, then goes back to the fan setting that I had it at. This does not happen when the fan is turned OFF completely - just when it's on - at any level. Has anyone had this happen? Is it worrisome? Am I about to short something out? Please let me know if you've seen it and dealt with it? Thanks! Quote Link to comment Share on other sites More sharing options...
naviathan Posted May 12, 2008 Share Posted May 12, 2008 Sounds like it could be the switch. If the contacts inside are loose they could be randomly making contact to the next level up. If it's not that, then I suppose the fan could be worn out or (less likely) you're getting voltage spikes from a failing regulator in your alt. Keep and eye on the voltage gauge when it does it. Quote Link to comment Share on other sites More sharing options...
BobbyZ Posted May 12, 2008 Share Posted May 12, 2008 Hey I have the exact same problem!! Mine is a 1981 turbo 280zx and has been doing the exact same thing ever since I got it. One thing I did check was the resistance in the variable resistor control knob. This seems to be working fine. The resistance varies as it is supposed to and at least when I checked it didnt have any strange behavoir. I think it is probably the fan controller going out but I haven't taken the time to fool around under the dash to figure out what is going on. I have a brand new alternator so I am pretty sure that is not the problem. It acts like a simple bad connection that sometimes is fine and then others it will bounce between faulty and functional. Quote Link to comment Share on other sites More sharing options...
naviathan Posted May 12, 2008 Share Posted May 12, 2008 The other thing I didn't think of is vacuum. When you're accelerating the vacuum drops which will cause vents to change position and might make it seem like it's blowing more or less. These old vents are all vacuum controlled so that could be part of it. Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted May 12, 2008 Author Share Posted May 12, 2008 Thanks - I think that will be my next step (taking out switch and examining). This worked with my faulty hazard signal switch - just sanded off the corrosion and it worked like new! I'll check it out. The alternator was replaced a couple months ago and this happened before and after that so I don't think that's part of it - but thanks for the idea! I'll let you guys know what the switch disassembly yields.... Phil Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted May 12, 2008 Author Share Posted May 12, 2008 The other thing I didn't think of is vacuum. When you're accelerating the vacuum drops which will cause vents to change position and might make it seem like it's blowing more or less. These old vents are all vacuum controlled so that could be part of it. Thanks again! I don't think it's that on mine - I get the same symptoms, regardless of the gas being engaged or not - I can't tie to to the car's other behaviors - it's totally random. I'll check the knob/switch and see.... Cheers! Quote Link to comment Share on other sites More sharing options...
BobbyZ Posted May 12, 2008 Share Posted May 12, 2008 Ya it definately is not tied to vacuum. The blower motor itself has a huge increase in RPM's, in my car it actually gets really loud. Loud enough to be annoying over the top of the exhaust sound(muffler fell off few days ago so engine is now quite loud). Quote Link to comment Share on other sites More sharing options...
kralcniloc Posted May 15, 2008 Share Posted May 15, 2008 This same thing happened to my 83, i tested the switch with a DVOM and it seemed to be fine, but it still did it. after i replaced almost every other part, i wound back at the switch and even though it tested ok i replaced it and it fixed the problem. i think the vibration of driving was shaking the contacts inside and causing erratic operation. Quote Link to comment Share on other sites More sharing options...
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