What would cause belts to squeal when heater fan is turned on?

[Streetslug]

What causes my belts to squeal when I turn on my heat fan switch, only
squeals when switch is turned on at low rpms?
could this mean that my alternator is on its way out?

[Tim Helmuth]

Most likely your alternator belt is slightly loose or needs
replacement. When you turn your fan on it is drawing quite a few amps
and causing your alt. to work harder in turn causing belt slippage.

[The Wrench]

Sounds like the added elect. load is causing the alt BELT to slip and
squeal. Tighten the belt if loose.

Streetslug <stree...@aol.com> wrote in article
<19970101222...@ladder01.news.aol.com>...

[John Polasek]

If the belt squeal is being made by the alternator, the noise should also
occur or worsen when the headlights are turned on. (These lights should
pull more amperage than the heater blower motor.)

More likely, it is your a/c air compressor that is kicking on and causing
the squeal; modern autos normally cycle the a/c on when the defroster is
activated, as the drier air does a faster job defogging the windows...
but you knew that already. It may be that the a/c is kicking on
inadvertently when you want only heat on the feet. Just a thought...

[John Polasek]

[McFly]

The altenator expreses a load at the pulley absolutely directly
proportional to the electrical Load on the output
so as you increase electrical load so the pulley resists or brakes against
the belt
chech the tension if it is firm replace it they become glazed do not
tighten it tighter than normall it will kill the bearings of anything its
runs on bar the crank and that may include your water pump
get a new belt
by the way the latest Dynomometers measure engine load at a large altenator
by applying a known electrical load the the current supplied will
represent the horsepower of the engine driving it also counting the ac
pulse gives you exact RPM
groovy hey
Dave.
--
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[John J. Lopez]

Tim Helmuth wrote:
>
> >
> > What causes my belts to squeal when I turn on my heat fan switch,
> only
> > squeals when switch is turned on at low rpms?
> > could this mean that my alternator is on its way out?
>

> Most likely your alternator belt is slightly loose or needs
> replacement. When you turn your fan on it is drawing quite a few amps
> and causing your alt. to work harder in turn causing belt slippage.

If your vehicule has airconditioning, defrost will cause the compressor
to come on to reduse moisture etc. Check alternator and AC belts.

JL

[Paul C. Menten]

Streetslug (stree...@aol.com) wrote:
: What causes my belts to squeal when I turn on my heat fan switch, only
: squeals when switch is turned on at low rpms?
: could this mean that my alternator is on its way out?

Loose belt on the alternator/air conditioner. Subarus had a heater that
runs off the air conditioner pump! Try buying a can of belt dressing
and spraying it on the shiny fan belt.

paul

[JB]

In article <5av6fn$4...@hpbs2500.boi.hp.com>, pcme...@boi.hp.com says...

--
You mean at low engine RPMs? Or low blower RPMs? If low engine RPMs check
for loose alternator belt, if low blower RPMs check for bad bearing in
blower motor making the same type of noise.
Jordan Blessing L1 Master Tech

[jerrodfran...@gmail.com]

So mine does it when I turn the head lights on and it if I have the heater on high at low rmp's. So your saying I need to replace my alternator belt right?

[Steve W.]

The belt OR the tensioner or both depending on mileage and climate.
The reason for the squeal is increased load on the alternator causing
belt slippage.

--
Steve W.

[kdtri...@gmail.com]

I have a 2015 Toyota Camry when I turn on my heater doesn't matter if it's at low or higher RPMs it has a squill not high but it does squirrel a little bit just wanted to know what your thoughts were on that

[kdtri...@gmail.com]

I have a 2015 Toyota Camry and when I turn on my heater whether it's at low or higher speeds it squeals not too high of a pitch just irritating pitch what are your thoughts

[Scott Dorsey]

In article <e531a849-1976-4e19...@googlegroups.com>,

<kdtri...@gmail.com> wrote:
>I have a 2015 Toyota Camry and when I turn on my heater whether it's at low or higher speeds it squeals not too high of a pitch just irritating pitch what are your thoughts

When the heater is in defrost, the AC compressor is kicked in. Retension
or replace the AC belt.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Steve W.]

Scott Dorsey wrote:
> In article <e531a849-1976-4e19...@googlegroups.com>,
> <kdtri...@gmail.com> wrote:
>> I have a 2015 Toyota Camry and when I turn on my heater whether
>> it's at low or higher speeds it squeals not too high of a pitch
>> just irritating pitch what are your thoughts
>
> When the heater is in defrost, the AC compressor is kicked in.
> Retension or replace the AC belt. --scott

Also, are you sure it's the belt? A bad bearing in the blower motor
could cause a squeal.
Belt wise you have the increased draw on the alternator from the fan
motor, and as Scott said, in defrost the compressor engages as well.

I would check the tensioner and the various pulleys and the belt itself
for wear. Do you hear any squeals when you rev the engine? How about if
you turn on the fan and rev the engine? What does the squeal do?
--
Steve W.

[Arlen Holder]

On Thu, 12 Mar 2020 23:49:30 -0400, Steve W. wrote:

> Also, are you sure it's the belt? A bad bearing in the blower motor
> could cause a squeal.

Just to add an experienced +1 to that comment above...
o I've had intermittent squeals that lasted for months that were bearings;
o I've had intermittent squeals that lasted for months that were belts.

I tried the stethescope diagnostic method, which many people suggest, but
an engine is so loud that, personally, I find that method worthless.

I also tried the spritzer of water on the belts method that many people
suggest, but, again, I found that method almost worthless in my tests.

I never was any good at pressing on the belt to test the tension (and I
don't trust those tension gauges any more than my finger), where tension
isn't everything anyway (although visual inspection is pretty good).

In the case of the bearing squeal, it finally manifested itself in the $5
alternator bearings having been the culprit, where the rebuilding took me a
weekend as breaking open an alternator isn't as easy as you might think.
<https://www.alibaba.com/showroom/alternator-bearings.html>

In the case of the belts, the alternator belt eventually broke,
necessitating a parking-lot replacement of the broken belt.
<https://www.alibaba.com/showroom/gates-alternator-belt.html>
--
Together we can learn far more than anyone of us can by learning alone.