Why is the heater blowing cold air
How to Fix a Car with No Heat (Easy)
hey guys chrisfix here and with the
colder weather around the corner today
I'm gonna show you how to diagnose a
problem where you don't get heat in your
car truck before we begin anything turn
your car or your truck to the run
position and you just want to make sure
that your temperature gauge here is low
you do not want it to be in the middle
or high because the first test we're
gonna do is to check to make sure that
we have enough antifreeze in the car and
you can't check the antifreeze when the
engines hot you get heat in your car
because that radiator fluid that gets
really hot runs through the engine
through the piping into your cabin where
there's like a mini radiator that mini
radiator holds hot coolant it's called
your heater core and then a fan blows
over your heater core and that's how you
get hot air and then when that coolant
is cooled just a little bit because you
have a fan blowing over it it gets sent
back into the engine so if you don't
have enough coolant your engine might be
able to run at the correct operating
temperature but because the heater core
is so high up into the vehicle there
might not be enough fluid to get into
here and give you heat inside your car
so the first step we're gonna do since
the engines still cold we're gonna go
check the radiator and see if there's
enough fluid in here you just spin it
counterclockwise and then when it won't
spin any more you press downwards and
spin it until it comes off Wow I'm
definitely going to need to change this
fluid very soon you can see it's all
gunked up and that will bring me to
another reason why you might not have
heat but we'll get to that a couple
seconds you can see the coolant is right
up to the top here so this radiator is
filled and now we'll put the cap back on
and just twist this clockwise until it
firmly snaps into place you wanna make
sure that this is on correctly because
this is a pressurized system your car
might not have a radiator cap like this
so just check your owners manual it'll
tell you how to check your coolant
that's just one of those basic things
that every owner's manual has also you
might have a coolant reservoir that you
should check you could just go in here
and see if there's any coolant and in my
case there isn't any coolant so I'm
going to add a little bit when you're
adding coolant to this you want to go
and look there's a cold fill line you
can see it all the way down there it
says cold fill that's where you gonna
fill this up when the engine is cold so
I'm going to add some coolant make sure
you check your owner's manual to make
sure you're adding the right type of
coolant
okay so now we know that our radiator is
filled and we topped off our coolant
reservoir now we can properly test the
heating system and see if we have heat
filling your radiator up with just a
little bit of coolant like this might
just be an easy fix for your no heat
problem so now we're gonna go for a ride
so that we could heat up our engine you
want the temperature gauge here to be
between the C and the H right in the
middle and that's how you know your car
is heated up and at that point you
should have heat in your car so I'm just
finishing up my drive you can see the
engines at operating temperature and now
that the engine is warmed up let me show
you the other steps to diagnose a
vehicle when you don't have heat so I've
been driving around for a little while
and that gauge has been pretty stable
right there but if your car is
overheating then the reason why you're
not getting heat because the water pump
isn't working
typically a bad water pump will leak and
the impeller will still spin but if it
doesn't spin the hot coolant won't be
forced into your heater core or even
your radiator so your engine will
overheat and you won't get any heat in
the cabin you also might have a problem
where your car never gets hot it doesn't
get up to operating temperature and this
could be due to the absence of a
thermostat or your thermostat stuck open
to find your thermostat all you have to
do is follow that top radiator hose into
your engine once you find your
thermostat all it is is two bolts one
there one there you unbolt those you
take the old thermostat out put the new
thermostat in and close it up so in this
case since our temperature gauge is
right in the middle
we know that the thermostat and water
pump are good just to let you guys know
in my truck I actually have heat
everything is fine I'm just going
through steps for you so if you don't
have heat or if you have a little heat
you could diagnose the problem yourself
so after the car is warmed up we're
going to turn the heat on all the way
and then we're gonna put the heat on the
floor so my fan is working when it's on
low it works when it's on medium and it
works when it's on high if your fan only
works when it's on high
and you're not getting heat or a fan on
the lower settings then your blower
motor resistors probably bad and I have
a video on how to replace that it's not
a big deal it's a pretty cheap part and
it's pretty quick and easy to replace
now if your fan doesn't work at all you
have it on all the different speeds and
it's not working then your blower motors
probably bed and I also have a video on
how to replace that but if your fan does
work and you're still not getting heat
or it's not very hot there could be
other problems let's say the air coming
out isn't really hot like it's a little
warm but it's not as hot as it should be
what that typically is caused by is a
quad heater core to check for a clogged
heater core make sure you heat is on and
we're going to go outside to the engine
compartment when we look at our engine
compartment what we want to do is we
want to go back to the firewall
typically on the passenger side or
somewhere near the middle you're gonna
find two hoses these two hoses go into
the firewall and these are your heater
core hoses so with these two heater core
hoses what you want to do is you want to
touch them you want to make sure that
both of them are hot right now it's
about 35 degrees on the blacktop so
imagine how cold it is outside and then
I'm gonna turn the laser on so you can
see where I'm aiming I'm aiming right on
the hose and it's about 140 degrees now
I go to the other one same temperature
140 so both of these are the same
temperature they're both warm they're
hot to the touch make sure you don't
burn yourself when you're doing this so
I know my flow is good so if you have
one that's hot and one that's cold the
first thing you want to do is check the
heater control valve which is this right
here
in my case my heater control valve is
run by a vacuum in your case it might be
electronic or mechanical either way all
you have to do is turn the heat on and
shut the heat off and see if this moves
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so if your valve is working it'll move
in and out if your valve isn't working
it won't move now if your heater control
valve isn't working you're not gonna be
able to get heat because it won't let
coolant flow into your heater core and
if that's the case you just need to
replace one of these now if you just
want to set this up real quick so that
you have heat without fixing this all
you have to do is take the vacuum line
off and then clogged up the vacuum line
here you don't have a vacuum leak now if
it doesn't open up when you take the
vacuum line off just manually open it up
you can even tape it or rubberband it to
something so that it stays open now
that's just a temporary fix but it's
something so you have heat if you have
an electrical one of these you can
unclip it from the wiring harness and
test it to see if it's getting power
when you turn the heat on if it's
getting power your heater valve is bad
if you're not getting power then there's
a problem with the hvac under the - if
your car has a mechanical heater control
valve when you turn the dial for your
heat you move a cable that opens the
valve instead of using vacuum or
electrical motor this cable can
disconnect and many times you just need
to pop it back into place to fix the
problem and remember if you can't find a
heater control valve your car might not
use one so don't worry in my case this
works fine so let's move on to the next
thing to diagnose the other reason why
one of your hoses will be hot and the
other will be cool or slightly warm is
because you have a clogged heater core
you can attempt to reverse flush the
heater core by taking off both of the
hoses and running water through them to
flush any gunk that's in there and might
be clogging it up you could use a garden
hose but make sure you use very low
pressure because you could damage the
heater core I have a video on flushing
the heater core and the link to that
video will be in the description now
let's say both of your lines are cold
and your heater control valve is working
properly you might have air in the
system since this is one of the highest
points in your cooling system there's a
good chance that air could get caught in
here to fix that all you have to do is
bleed your cooling system and sometimes
with the heater on a few good revs of
the engine will force that air out and
that coolant in now one of the last
things I'm going to go over to diagnose
the heater system if you did all that
and none of that worked well you could
have a bad blend or actuator in some
cars like this it's mechanical in other
cars it could be moved with an
electrical motor or using engine vacuum
now what a blender does is it's a door
that blocks
either the air-conditioner or the heater
so if you turn your temperature to the
cool position right now the blend door
will be blocking the heater core you
don't want air from the heater core
because you just want cold air now if
you turn your heat on then the blend
door will be blocking cold air coming
from the car the blend door can also
allow both hot and cold air to come in
at the same time to get a desired
temperature typically if you change your
temperature quick like that you'll hear
like a knock and that's the blend or
just slamming shut I'm gonna change this
quickly and we'll see if you could hear
it so in mine you could hear the blend
door opens and closes it's just that one
click or one knock and it's functioning
properly
if you don't hear that on yours when you
turn this quickly or if you hear a
clicking so if I go from here to here
and it's making like a deer stripping
noise or like a plastic click like click
click click click and then it stops that
could be the blend or actuator which is
up under the dash and it's connected to
the blend or and it's just an electrical
motor and the gears strip overtime and
then your blend door won't move so it'll
be stuck in either this position or
it'll be stuck in that position either
allowing cool air or hot air into your
car so all you would have to do is
replace that blend door actuator and
that'll fix the problem or in this case
since it's mechanically connected from
the switch to the blend door you can
look behind here for a connector that
popped off and just reconnected the same
goes for a blend door that works off of
engine vacuum just look for a loose
vacuum hose and reconnect it now these
are the most common problems for no heat
situations I hope this video helps you
diagnose your problem as always you
could comment below with any questions
also remember to give the video a thumbs
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button the top tip for this video is a
basic maintenance tip on how to prevent
a no heat situation because nobody wants
to be left in the cold for their Drive
the best way to prevent many no heat
problems is with a coolant flush every
few years and now if you're unsure if
your coolant needs changing one way to
test it is with the multimeter with the
engine cooled down take the radiator cap
off now start your engine
and put the multimeter on 20 DC volts
and take one of the leaves and put it in
the coolant but only touch the coolant
not the side or the metal of the
radiator down below it and take another
lead and put it on the ground if the
reading is point three volts or more you
probably need to change your cooling
there are other methods to test your
coolant and also I'll get more into this
multimeter method in another video and
the link to that video will be in the
description below
