Ford Fiesta 2008 WQ - AC pressure test

[dckmedia]

Hi All

I have an issue with my AC, which it is not doing a good job on hot days(above 30c days)

On a normal day(outside temperature less than 30), I can hear AC clutch cycles on constant time periods and AC is cold enough, but when the outside temperature is above 30, I can hear the clutch cycles frequently than a normal day, and AC is not very cold.

I have tested the system using the manifold gauge and below are the readings.

Car not started - Static system pressure
Outside temperature - 21c
AC High gauge - 65psi
AC Low gauge - 70psi

Pressure gauge - static pressure reading - image

When I reading about the static pressure on this forum, I found most people saying static pressure should be equal on both sides, but mine seems to be 5-10 psi less on the high side.

Then I started my car turn on the AC and I have recorded the movement of the gauges you will find it in the below video.

AC pressure test video

When the AC clutch engaged, the high side goes a maximum of 110 - 120 psi only and I can hear the AC clutch turns off. Also noticed that the indicator of the gauge is a bit wobbly when it reaches 110psi. I don't think the gauge is faulty as I have connected it to another car of my fried and it seems to have no issues.

I don't have much knowledge about car ac systems, but every form i read people mention the high side should be at least 150 psi but mines cut off near 110. Is it a problem with my high-pressure switch? or im low or high on R134a

Any diagnostic advice much appreciated.

[Luke Plaizier]

Can you see this link? It has some handy troubleshooting steps regarding the high pressure and low pressure switches. Given I am 8 months late in replying I assume you have solved your problem by now?

http://fordforums.com.au/wsmpub/wq95/412-00.html

Luke