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after some driving the central air vents make a "whistle" that changes with air vent speed. there is no cabin filter in our car and I don't know exactly if the vent is easily reachable to clean/inspect.
Can someone offer me guidance to check where this whistle come from and how to get rid of it?
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Just to help clarify and be more precise for us
a) The whistling sound is coming from the two face vents at the center console? Would you say it's inside the console more at and in the vent or down in the console perhaps in behind the vent controls? Lower at the blower motor?
b) The noise varies with fan speed? More to do with blower motor speed or air flow speed?
c) Is the noise best described as a "whistle", a "hiss", a "chirp" or a "squeal"?
d) With the fan on high, all three control buttons out and all four face vents wide open and pointed straight out, does blocking air flow with your hands make a notable difference?
e) With the fan on high, which vent control button positions make it worst? Is the air recirculation button the one that causes the creaking?
My fear for you is that it's the dreaded 240 blower motor. The bearings wear and dry out which may start out as a chirp then a whistle and at its worst can best be described as a squealing stuck pig. It's the absolute worst job imaginable in a 240.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Did two tests today. First with car running but with the roof open, maximum speed and all positions.
Impossible to stay for longer with the temperature at maximum because I would have died crunchy with the crust like a pork :p and another engine stopped.
In the second you can hear the "whistle" at idle. In both cases, however, the worst noise cannot be heard, because I should have kept the temp at maximum for longer... But was way too hot!
https://youtu.be/IpCV9OIRO54
https://youtu.be/R3hAqtL5m48
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That's excellent for posting those Youtube videos to let us remotely help you with the diagnosis. I've now listened carefully on my good speakers to your tests.
What I'm hearing as abnormal (and to use my own words) is a low volume owl "hoo" sound at the low fan speeds 1 and 2. My observations include:
o I'm assuming the overall hummm sound is normal operation and mostly that your microphone is in close and sensitive to background noise. If that's not the case then I'd need to rethink all this.
o This "hooo" does not sound like bearings or anything mechanical or plastic vibrating.
o It's just an air noise, a harmonic vibration of air currents, at some kind of sweet spot in air flow conditions, like at a narrow opening, and in that sense a whistle as you say.
o The noise in the videos appears to be happening with the face vents fully open and only when all buttons are out, meaning the floor vent flap and defrost vent flap are in theory fully closed and the recirculation vent for outside air is in theory fully open. Air is basically mostly just coming out the face vents in addition to normal small air leaks (the system is not air tight).
o It also only happens after running the fan speed up high, playing with the controls, and then lowering the fan speed back down before the noise starts up.
I'm unable to imagine this noise coming from the fan impeller (one on each side of the blower motor).
I suspect the noise is coming from either a) an internal vent flap that's not fully closing, or b) an air leak at an air duct tube connection. In either case it's not serious.
You will need to do further testing to try to isolate where the sound is happening.
The question for me now is not what it takes to make the noise start, but rather what it now takes to make it go away.
Just as a final test, the first thing I would do is while it's 'hooing' to manually block air flow with your hands at the defrost air vents on the top of the dash. There's a fair bit of ducting associated with those vents and things may not be well sealed at the duct connections or at the plastic bezel on top of the dash.
If I was trying to isolate this further, I would now remove the console side panels (under dash panels and glove box) so you can try to figure where in the air distribution system the noise might be happening. Using your ear, figure which side is worst or whether it's in the center console air distribution box and whether high or low in that box. With a length of vinyl tubing to your ear, use it like a stethoscope to see if you can isolate the noise to an area. There's a fair bit of wiring up underneath including relays tucked in various spots, so getting up into some locations may take a bit of effort.
Next thing I would do after that is find each vent flap actuator on the outside and while the 'hoo" sound is happening to manually force each vent fully shut or open it up a bit trying to make the sound go away. Failing that, I would then proceed to put my hand on every air duct tube connection trying to alter conditions around the duct connections.
If I had to wildly bet, it's either at the floor vent flap or else the air recirculation flap rather than the defrost vent flap.
Note that the recirculation air vent flap does not fully close off outside air in the Recirc position. A little fresh air is always supposed to be getting into the cabin.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Thank you Dave for your response.
Yes, the "whistle" is more that this low volume owl "hoo" sound at the low fan speeds 1 and 2. Sometimes seemes more high pitched, but is that sound.
Obivously, NOT so bothersome but being the car very quiet (low mileage, never dismantled a single plastic so no creaks, engine round and not noisy) is something you can hear when you became "used" to the car, and (honestly) being very anal at little imperfections. Something an average driver wouldn't ever notice maybe.
As said I was almost sure that sound isn't from motor but you and other folks are surerly more skilled than me about that car. Surely for that slight, imperceptible annoyance I wouldn't dismantle any plastic, wire and screw being there from 44 years and being sure that if is some gasket dried...surely soved the one whistling, the other ones once moved would became worst than this one.
The noise I was hearing at full hot and full speed, yesterday wasn't simple to recreate, being a warm day and impossible to go for 5,10 minutes at full heat. But if it'll be the only condition to hear it, I think I can live with it for the same reason above, if it won't get forse at lower speeds and temperatures.
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Hi Dave,
My speakers aren't that good, and for that matter neither are my ears, but that resonance I hear reminds me of what I heard when a man I met in another city let me hear his, I think 1981, 240 he'd just got back from the mechanic. Spent $1100 to get his blower motor replaced. I took down the felt above the passenger's footwell and looked up at the outer surface of the right side volute. I was surprised to see it was covered almost entirely with a cut up cardboard box. Some sort of chainsaw job, and he didn't know if originally that way from the previous owner. I can only imagine the conversation he had with his mechanic about that; I never heard from him.
--
Art Benstein near Baltimore
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it seems like two hours. That's relativity." -- Albert Einstein
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IN DEFENSE OF CHAINSAWS -- I've replaced many 240 heater motors using both methods depending on circumstances. Customers cars get taken apart completely. Used cars getting a chance to be put back on the road - may be a candidate for the "chainsaw" - which is an exaggeration - no actual chainsaw is involved. The early models required complete disassembly as the new type replacement motor had an outer casing where the original has no outer casing. Those models required grinding out the inside of the heater box to accommodate the larger new motor. That operation causes a huge amount of "sawdust" which you vacuum up as you go -- but when done you turn the fan on and plastic dust comes flying out of every vent - there's another half hour vacuuming. The motors get installed and removed from the left side so the only reason to disassemble the right side is to get to the clip holding the right side fan blade to the shaft. By cutting a 3 inch hole through the R/S outer panel you can reach the clip and save having to remove the glovebox and all the vent tubing connections. I hope no one is offended-the Volvo 240 is a great car and I have loved all the models I've owned--but it's not a Duesenberg--if the solution gets it back on the road, it's Ok with me. - Dave
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Hi Art. I'm not sure who I'd feel sorrier for, the owner who spent $1100 on a blower he may not have needed or the mechanic who only billed him $1100 for doing such a miserable job. Problem there is it's hard to imagine a mechanic not noticing and mentioning finding a cardboard box repair, so that does makes you think some ductwork got damaged during blower replacement and in frustration the mechanic went for a duct tape and cereal box solution just to get the job over with and the car out of the shop.
For the OP here, I think some exploration under the dash is well warranted with the expectation that the blower motor is still perfectly okay at such a low mileage, despite the age. I think the vent flaps have a foam insulation strip around the edges to act as a seal when closed and also prevent noise as they close. If the adhesive dried out and the foam strips came loose it could cause the vents to stay open a hair when being closed with the air flowing at higher volumes. That would really require opening things up to find and fix if that's the case.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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I wasn't able to edit the thread post (is it feasible?) with the "most important" issue I have found.
have to specify two kind of conditions to explain best, referring to the updates described here: https://www.brickboard.com/RWD/volvo/1690867/220/240/260/280/whistle_central_air_vents_noises.html
- "normal" conditions : comfort heat temperature/no heating required, low speed fan
-"full load" conditions: heat on maximum, like you can barely put your hands on the central vents for the big heat, and fan speed at maximum.
a) The whistling sound is coming from the two face vents at the center console? nWould you say it's inside the console more at and in the vent or down in the console perhaps in behind the vent controls? Lower at the blower motor?
* *in "normal operating conditions" is someting as a very light "hiss" I can hear fron the central vents, I think obviously because are the nearest from the blower. Comes from "inside", I'll say is something like a turbolence.**
b) The noise varies with fan speed? More to do with blower motor speed or air flow speed?
**in normal conditions, maybe full cold and first speed it becomes udible after 1/2 hour of travel or more, at second speed it disappears. I could also hypothesize that I agree with it after a while just because I become accustomed to the background environmental noise
in full load conditions, it get worse at full speed. at lower speed decreases/disappears.**
c) Is the noise best described as a "whistle", a "hiss", a "chirp" or a "squeal"?
**normal condition: a very light whistle.
at full load, it's the sound of plastic scraping on other plastic or metal, at a good volume**
d) With the fan on high, all three control buttons out and all four face vents wide open and pointed straight out, does blocking air flow with your hands make a notable difference?
**not tried honestly.**
e) With the fan on high, which vent control button positions make it worst? Is the air recirculation button the one that causes the creaking?
**no notable difference. the "whistle" at normal conditions is quite subtle. in full load conditions, the "cracking" is so loud you can't tell difference :p**
My fear for you is that it's the dreaded 240 blower motor. The bearings wear and dry out which may start out as a chirp then a whistle and at its worst can best be described as a squealing stuck pig. It's the absolute worst job imaginable in a 240.
**yes, I've read about it. my car is very low mileage but has obviously 43 years, so I think lubing may be an attempt or a palliative to stave off the biggest problems over time.
I studied a little the blower motor case and I'm of the idea that in the "full load conditions" heating somehow/somewhere expands plastic of the fan or the blower assembly and, combined with a dry bearing makes that horrible noise. SOmething like that you can hear there at 25:02 https://www.youtube.com/watch?t=1503&v=k18wMID1pNU
I've read 1) what should be done correctly, 2) the rough chainsaw method alternative and obviously my goal is to delay the moment of getting involved as much as possible because I discard the second option a priori. Messing with old, brittle plastic bits and wires is something in old/historical car is not the best thing to do, expecially when they are still totally pristine and the issue is not something that invalidates or prevents the use of realiability of the car but it is an annoyance that should simply be avoided. So I was gettiong opinions about.
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The heater blower noise seem quite bad. It is possible that a spherical bearing is fudged on the motor shaft and can't follow at full speed.
Many years ago I posted some pictures showing a cut view of the motor inside. This is for the new motor type starting around 1985 may be. Your motor is a little different on the outside. The casing has 3 legs and it is held in place with rubber bushings while the new type motor is inside two half moon shells with foam cushions in between. The motor inside is the same. The pictures show where to drill holes to bring lubricant in the right place. I could send you cut view of the older motor style if you need it. The right side hole drill location is a different picture but the left side is the same. If you use solvent to release fudged bearings it must be NON FLAMABLE.
At the mileage your car is, the motor bearings and brushes/rotor and commutators are far from being worn. If nothing has quit inside it could be lubricated ( I mean the two brass bearings are still held in their motor cover cavities with the springs). If the crimped washer pushing the spring that pushes the bearing in the motor cover is loose then the rotor bounces around on the stator. Because nothing hold it centered.
I am sorry that the pictures were too large to fit well with the text.
You can see pictures of newer motor cut views at bottom of page 20, sept 22 2017. You can reach that page by pressing many times "show more" at the top of this page. The post title is "Squealing interior vent fan" at bottom of page 20.
I did lubricate my 1982 and 1991 240 and it worked well. Center console must be removed and all wires identified. I used a 1 3/4 hole saw to cut into the plastic heater box. For the motor a sharp point 6 inch long bit is required to start drilling the holes and use a 1/8 inch bit to finish. Not everybody has
this kind of equipment.
The post title is: brickboard.com/RWD/volvo/1649374/220/240/260/280/squealing_interior_vent_fan.html
Prepare to replace the motor if something is broken. Do not forget to visit Art Benstein's site which is "cleanflametrap.com". It is fabulous.
Good luck Rolandp
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thanks. I already studied cleanframetrap site, unfortunately I can't find "chainsaw method" pics, just for informations' sake.
I don't think the vent is bad, due to a low mileage and usage: the noise showed only with full hot temp and fat at very high speed, sign that may not be 100% "firm" but something expanding in a very quick mode due to heating made it evident, otherwise there are no noises at all. the "whistle" I can hear in the other situations is very subtle, and I don't think is related.
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My goodness, that's quite the noise at 25:02 in the video. Between that and the whistling/squealing I would say your blower motor is likely going/gone. The bushings must be dry enough and worn enough to allow the impeller to shift sideways on its axle depending on the combined blower and air speed to now scuff against the motor housing.
Way back, one of our main contributors, Don Foster, came up with what he dubbed "the chainsaw method" to remove and service the blower. Others go the full meal route and need to take the dash even more apart, but nowhere near as much as in that video.
Another of our 240 experts, Art Benstein, did an excellent job of documenting both repair procedures with pictures. You can find it here on Art's website https://cleanflametrap.com/ . Also in that article is a link to a copy he saved of Don's chainsaw procedure.
As for just lubing it, it's something people have tried with only limited success. It may be worth trying, especially if the chirping is just beginning and only if you're somehow lucky enough to get a drop or two of oil on the bushing.
Way back, and I mean way back, there was once an article showing the locations of precisely where and how deep to drill a hole so you could load it with a few drops of 3-in-1 oil and try getting it around the bushings. I can no longer find it.
I was once able to successfully lube a chirping late model 140 blower, which is very similar, if not identical to the early 240 consoles and blowers. This has to be around 35 years ago so my recollections are admittedly a bit hazy. I do recall it took a fair bit of effort and patience to unclip the motor housing end panels to get the impellers off so I could get a bit of 3-in-1 oil on the bushings. I recall feeling lucky that I somehow succeeded in sliding down the very highest clips to be able to remove them. I vaguely recall getting the impellers off was not trivial. It was then that I realized that the drill hole method people were talking about may have been a decent option. I'm trying to remember if I then drilled a hole in the magic spot and got in a bit of oil, but if nothing else I was able to get some oil at the end of the bushing. I also vaguely recall putting an oil saturated felt washer behind the impeller or perhaps it was a thin fibre washer with a drop of oil behind it. The fan was just beginning to occasionally chirp and this silenced it for the remainder of the 15 years I had that 140. Being able to get a thin washer there would also prevent the impeller moving sideways and scuffing on the housing. You could always start by trying that and knowing the odds are high that you may not succeed and you'll end up having to carry on and replace the blower. It may be that 240s have a little less clearance than my 140s, in which case you may not be able to use my method.
Hissing sound are usually leaking vent control buttons and actuators.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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..I found too that with full heat, the vent starts to make "craking noises". So I think it's time to check/lube it. Need infos about ;)
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Mine has the 3 buttons but no AC.
Italian market.
so I think has the CU system
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