Thank you for the site. However,  i found an error in the description of
how an Thermal Expansion Valve operates in the site ;  the text says :
'In an expansion valve air conditioning system, refrigerant flow to the
evaporator varies according to the pressure in the suction line
(evaporator outlet). This is detected by a sensing bulb mounted on the
line, and relayed to the expansion valve via a capillary tube
'

The refrigerant flow to the evaporator is varied NOT according to the
pressure in the suction line , but rather is it based on the pipe
surface TEMPERATURE as sensed at the outlet of the evaporator (suction
line)  by the sensing bulb that is strapped in close contact to the
suction line.  Its purpose is to maintain a certain superheat value
(typically 8-12 degrees f.) so all of the liquid refrigerant is
evaporated as it makes it journey thru the evaporator as well as picking
up additional heat (superheat)  to ensure that only vapor refrigerant
exits the evaporator... as a compressor is only designed to pump 100%
vapor to avoid possible damage.

Further...under the Recharging Section of the site ,  there is another
error . The URL for this section in the site is as follows :
Address:http://car-air-conditioning.blogspot.com/2007/05/ac-recharging-method.html

In each of the charging methods listed, it says to hook up the hose to
the air conditioning systems' access port then to connect the can of
Refrigerant and allow the freon to go into the system ;  this is
incorrect and a bad practice because air which is present the hose will
be forced into the air conditioning system if these instructions are
followed. Air and moisture are the two things which must not be allowed
to enter any A/C system . The text should have explained the absolute
necessity of purging the air out of the hose before releasing the freon
into the system.

This is one example of why disposable cans of freon should NOT be sold
to the general public , as seldom does the average Consumer follow
proper guidelines for recharging an A/C system, plus there is alot of
danger handling freon in these containers.  Summarizing, you have to
know what you are doing when it comes to charging an A/C system and it
must be properly and accurately metered in ;  you do NOT just fill 'er
up  as you would a gas tank.  

There needs to be greater regulation concerning aftermarket A/C products
that are sold to the general public before more people end up suffering
bodily injury (eye injuries and burns mainly) to save money, in addition
to messing up their A/C system ... only to have to take it to a
qualified A/C mechanic anyway.