View Full Version : How to define system is sufficient charge for cars

04-06-2007, 05:00 PM
May I know how to check the system whether is sufficient charge for R-134a?
System have no liquid sight glass.
What is the usual delta T across evaporator coil and on what fan speed to check.
To read suction and discharge pressure at what engine speed?
System takes a long time to cool during the day when car was being parked under the sun.
But can cool well after sunset or on raining day.

Thank you.

04-06-2007, 06:28 PM
R.T.F.M is the only true way

I had to google to see what he was talking about:eek:

I cant stop laughing now:D

C Bagtas
04-06-2007, 09:54 PM
the simple way is just touch the suction pipe,if it is cold you are nearly in the correct charge of gas.and if you have thermometer what i remember max. is 13 degrees C.check the air temp.in vent near to window.if it is below 13 c your cooling issatisfactory.

Karl Hofmann
05-06-2007, 12:28 AM
With the advent of variable displacement compressors, the only way to check the charge is to recover and weigh what was in there. the correct charge weight may be on a sticker under the bonnet

The vent temperature varies widely from one model to another depending on the airflow of the vents, some cars rely on a high air flow and higher vent temps, others have a lesser air flow and have a lower vent temp, the manufacturer should have the required data for the delta T for a range of ambients and RH

Don't forget that in the summer, the interior of the car stores a huge quantity of heat and so will take longer to cool down than it would in the evening

Generally I tend to check the centre vent temperature with the fan on full, recirculate on and the engine at 1500rpm

05-06-2007, 09:06 AM
R.T.F.M is the only true way


RTFM, then if it still doesn't work, do what its says!


16-06-2007, 12:39 AM
Years ago, I had a device called an electronic sight glass, which clamped onto the liquid line at two points and beeped when a bubble went by. If there is still such a device, it might be able to be used to find the fully charged point. My electronic sight glass was made by Snap-on Tools.

18-06-2007, 08:40 AM
I had to google to see what he was talking about:eek:

I cant stop laughing now:D

:D UTFG is also the good way for u..

21-06-2007, 09:20 AM
There are CDs available called AUTODATA.

They are a bit expensive if you have to buy them, but if you go to computer fairs it is amazing what is available.

They tell you where all the components are in the car, how much refrigerant etc.