welcome back ac lesson number 14 daydreams
normal and abnormal gauge readings let's start with normal what is normal well according
to the pro-demand the following is normal that's what it says normally
functioning ac system remember the four ingredients to normal can you fill
in the blanks the correct amount of blank blank hitting on all cylinders good cooling of
the blank and something that starts with a c you remember these are the four ingredients to
be normal fill in the blanks i hope you did well the correct amount of refrigerant compressor
hitting on all cylinders and good cooling of the condenser circulation of the refrigerant all
of these ingredients are just as important as the first one the second one and the third one if any
of the ingredients are off it's going to affect the performance of the cooling back to normal
it says it normally functioning ac system great what is is this normal i'm
asking you is this normal no and i hope you remember why we're special here
in texas extreme severe heat look at the pointers the blue one can we round off that number 29 to a
30 on the red and we round that number off to 200 so yes we're gonna round off the two numbers the
blue number is 30 and the red number is 200.
Let's look at this chart some of you might remember
that these pressures are affected by temperature we'll start with the blue one the blue one is
between 25 and 35 puts us right at 30. that's what this one is saying on the red we're off you
see the red the red arrow it's only saying 155. if we try to get closer to 200 you see
the arrows now let's go with the red the red arrow is pointing to a pressure on the
high side of approximately 200 but on the blue you see what's going on it's not 30 anymore in fact if
you rounded it off it's like 45. i call it split the difference here we're trying to get close to
what pro demand says is normal on this chart the the blue arrow is indicating close enough to 30.
the red arrow well we're stretching it a little bit but it's close enough to 200 but look at the
yellow arrow that's not corpus that's colorado you don't even need air conditioning when it's 75
degrees out there right each vehicle is different each specification is different throw in
some extreme operating heat conditions with dog days of summer and then you have
normal so what's normal good luck around here here's some more tables let me try to simplify it here on the yellow arrow that's where we
are right now in the summer summertime we're easily between 90 degrees and 100.
Yes the
humidity makes it more difficult to cool us down yes i'm pointing to the right one it's always
high humidity in the summertime the yellow arrow we're always hot on the green arrow we're
almost almost always human the blue i'll keep for the low side the blue says about 35 37 and
on the red we have some more pressure readings here's some more readings let's see if we can do
anything with these this is one reading for one particular vehicle this is another reading
for another vehicle they're not identical each vehicle is different but we have to throw in
ambient temperature the yellow arrow close enough the green arrow absolutely on the blue 50 could
be normal this thing about normal and abnormal can get a little tricky let's go on there's no
question about it on the bottom temperature okay the temperature affects the pressure the
higher the temperature the higher the pressure i'm going to show you these
three different gauge readings i'm going to start with what's called normal
another normal now i just got this off the internet copy and paste but let's take a good look
at it right there under the blue gauge under the red gauge everything says normal this represents
a normal working air conditioning system if we now look at the blue pointer and we look at
the blue pointer sure it looks like 30 to me the red pointer yes you'll have to be able to read
this who can tell where we are we're at 175 psi this is normal that's what it says below the
blue below the red everything's normal here let's look first below the red right away it says well
that's too high can you read the number we're on the inner scale that's the psi the outer scale is
the metric unit we're at 425 that sure seems high on the blue they can't make up their mind is
it high or is it normal if we read the blue it's every bit of 50.
You see this now
look at it i did not do a switch-a-roo 400 on the red 425 is what normal is the
ambient temperature is what very high believe it have you figured it out our
pressures change with temperature especially with extreme severe heat anything above
90 degrees is considered extreme severe heat let's look at another one below the red it
says low below the blue they can't make up their mind why can't their make up their mind because
we haven't plugged in the ambient temperature it is abnormal is it low i'm not doing a switcheroo
look at it again on the red look at it that's 75 that's 75 psi if i was measuring temp if i was
measuring red pressure here in the summertime that thing's half empty but look what it says it's
normal if the ambient temperature is what low it goes both ways when the temperature is extremely
hot the pressure goes up when the temperature ambient temperature is extremely low the
pressures go down more about normal you remember these are the four ingredients to make normal
you should memorize them when we have all four ingredients the correct amount it's nice and cold
of course you can't read that and i don't need you to read it i'll explain at the top it says
normal now i hope you can count two four six eight nine we're going to go over nine abnormal
readings look at those those are crazy look at all those readings almost makes me busy
to look at all those numbers but let's go on our first most common abnormal reading in
my opinion is this one starting at the top low r134 charge the system is low on refrigerant
that's what the title says above the blue gauge is low above the red gauge it's low everything is
indicating low over here we have a couple of more symptoms on the blue arrow there's other things
to look at sight glass there it is a spike glass i almost stopped mentioning these because they
were gone but i am so glad they're coming back i haven't seen it yes i have i did see it
some of the newer vehicles on the liquid line now have a sight glass you see that little round
glass on top of that drying element that's the side clasp we used to use the side glass all
the time uh it was i couldn't understand why they took it away the side glass was the easiest
way not only to tell that the system was low but to hit your target charge as you were adding
the refrigerant you would look at that glass when the glass was white that means it was low as
the charge got to a normal level the white would turn to clear why is it low who remembers
is the refrigerant like gasoline it gets used up and you got to keep adding it every year no why
is it low because of leaks leaks and more leaks who doesn't believe it yet 80 percent of the
time the problem is the system has a leak what leaks everything compressors lead connections
leak operators leak condensers leak fittings leak hoses leak everything leak what part doesn't leak
everything needs any questions about low hong kong that's our first abnormal gauge vegan the next
one yes we start to get a little bit more involved at the top the blue arrows compressor malfunction
there's something wrong with the compressor above the blue gauge the blue's too high
the red's too low you see them over here what's wrong with it where they're telling
us that we have an internal compressor leak or it's mechanically broken who remembers
what goes wrong with the compressors well they're like an engine and they wear
out we have internal leakage here here the ring has decided to leave the groove but
remember is why the teflon rings decide to leave the groove because they're overheated and they're
melting this particular image shows plenty of oil on the moving parts compared to this one this one
doesn't have any oil and it's easy to understand why they wear out they're like engines that's
not going to go away they're still the same they're going to wear out because they
don't have oil they're going to wear out because they overheat or they're going
to wear out because of a combination yes that's an ac compressor off a vehicle what a
mess let's go on i gets a little more tricky here insufficient cooling of the condenser or
this is two things we're covering two things insufficient cooling of condenser is one problem
or refrigerant overcharge is another problem now above the gauges where are they let's keep it
simple above the above both gauges it says high the pressures are high and at this
point there's two things that will make both pressures too high one is the condenser is
not getting cool very well it's not sort of kind of nice it's an essential part of the process we
have to remove heat from the refrigerant it's part of the process you should have an idea why well
condensers get dirty nobody cleans them except me bully fans guarantee they're going to
wear out because if you know inside inside all vc motors are the brushes
these guys are going to stop working and now the air conditioning is going to be
affected and the pressures go too high here's a wiring diagram we can have problems with the relay
and the protection and some of the switches other problems that can cause insufficient cooling of
the condenser is that the fan clutch is slipping these guys don't last forever they might be
spinning but they're not spinning fast enough when the engine is hot and you're in stop and
go driving these fan clutches should hardly slip the only time they're supposed to slip is when
you're going down the interstate 75 miles an hour you have a ton of ram air the engine
compartment and passenger compartment is full that's why we slip it who knows why we
slipped the clutch there's a couple of answers one is to improve fuel mileage another one is to
quiet the operation these guys don't last forever dirty condensers damaged condensers 30 condensers
it's the same thing whether you're working on a house or a car this is an important part of the
process that's what happens when the pressure guess what happens to the pressures when the
condenser does not get pulled they go high and now we're destroying the compressor
we're melting the rings we're they're wearing out the compressor
next one we're still talking about the same thing insufficient cooling of
condenser or refrigerant over charge how does an ac get overcharged over charge means
too much freon well i'll tell you how rookies you gotta love them you trust that guy never in a
million years grace monkeys they used to call us that's not real that's a hollywood actor or
put some more the temptation is overwhelming to put a little extra refrigerant is not going
to make it cold ac pro is no help to the rookies more is not better it's very easy to overcharge
the temptation is overwhelming and the system will take it as fast as you put it in let's go
on next what does it say it says poor refrigerant circulation we're going over all the problems
the refrigeration system can have the first one i showed you was well it's low on prima
freon the second one i showed you while the compressor is bad the next one i showed
you either we're not cooling the condenser or somebody to put too much free on this is
part of the ingredients we have poor circulation look at the gauges they're doing something
funny the blue gauge has gone into negative vacuum now this is still a normal system
it's got the normal amount of refrigerant we now have another problem it's not on the
on the top of the list but it is on the list you should ask yourself and maybe you
have an idea what causes poor circulation we have certain several answers you've
seen some images i'm going to show you some more we have dirty tubes dirty valves
hooked up dryers and restricted condensers of course i have pictures there on the left
the new tube and then the one next to it that's not special hollywood makeup
i'm sure that's actual failure who knows what that is that's probably mostly
piston material teflon and that expansion valve they get restricted the passages are very small
it doesn't take many deposits from the compressor to plug it up whether it's the block style or the
90 degree style they're going to get restricted guts of the compressor whether it's metal or
teflon or whatever it is it's going to wind up at the tube at the valve what are we looking
at we're looking at a cutaway of the condenser why do i mention it and i told you last time the
new condensers are high efficient the passages are tiny when we have catastrophic failure of the
compressor it's pretty much standard procedure to replace the condenser we used to flush
them but nowadays the passages are so small we don't even try dryers now those are the
ones get plugged up the one on the right the red one that's the dryer i know the color's
off but they're at the bottom i want you to notice that's a screen and what happens is when the
screen gets dirty what we're doing is identifying the major proponents four of them that are likely
to get plugged up or restricted the sub says in the discharge in the liquid line no they don't
get restricted evaporators don't get restricted there's only four things that get restricted
and try and understand now let's go on and split some hairs you see the difference now now
they're saying there's no circulation as compared to poor circulation it's almost the same thing
here notice the the blue gauge it's in a vacuum whether it's poor circulation or no circulation
the gauges are going to act real funny on the blue sometimes we're getting down to the list here it's
possible moisture you have moisture in the system moisture is in the air the refrigeration system
all of them have not cannot tolerate moisture when moisture hits that expansion valve what
happens is it freezes instantly now the way you can spot it over here above the blue the blue is
on the left the low side read the word slide above the blue gauge one minute is normal and the
next minute it's in a vacuum what's happening well it's working normal normal normal and the
moisture it doesn't happen every single time it's a little hard to catch it right at the
incident occurs sometimes the ac is working man is working well and all of a sudden it goes
hot and then it goes cold and then it goes high when you have a system that one minute it works
and the next minute it doesn't and what i mean works i mean cold and when i say it doesn't it's
hot one minute is working the next minute it's not what's wrong with it it's possible it has moisture
we go out of our way to make sure that there's no moisture in the system mostly by pulling a
vacuum the more technical term is evacuation the important part this is not the most common but
it's on the list we're headed toward the last one the last of the list if you have moisture the
system works and works well and just out of nowhere it turns hot so it's possible the system
has moisture in it starts off normal they're really milking it here they're trying to cover
every single aspect air rookies here we go again when we're charging the system whether we're using
the gauges or the station both of us the station at and ourselves we take steps to purge air out
of our service hoses it is possible to have too much air in the system air is not cold brianne
is cold we don't want air we don't want moisture we want that good juicy refrigerant here our last
one or is it wait a minute what am i showing you here when you have air on the system above both
gauges look at it they're high now that should remind you of this one there's two things the
condenser is not being cooled somebody over charged it you see above the gauges it says hi
i'm not pulling a switcheroo this is what happens we actually have four things support them three
we have three things if there's air in the system the readings are too high if there's insufficient
cooling of the condenser buy if we have too much refrigerant the readings are too high let's go
on i believe this is the last one something about the expansion valve improperly mounted or here we
go two things now wait a minute again i was right there are four things that will cause high high
high high we can have them both high there's air in the system we can have them both high there's
insufficient cooling of the condenser we can have them both hives somebody put too much refrigerant
we can have them both high if the expansion valve is not mounted correctly or we have the sensing
ball the sense involved this particular type of expansion valve needs to know what the temperature
is of the evaporator you see the yellow arrow the sensing bulb has to be securely mounted to the
outlet of the evaporator pictures are better the blue the yellow arrow on top that's the beginning
of the sensing bow the yellow arrow on the bottom that's the sensing ball the sensing bulb has to
be securely attached to the out of the evaporator and some of this tar tape you see on this
particular image we have the same thing we have the same sensing bulb but it's under a tar tape
this looks like this might be a good place to stop
