Aircon compressor testing

Tested my aircon compressor today or at least attempted to as my aircon is not working. Gave it a direct feed from the battery and all it did was 'click' ,it didn't come to life at all other than the relay sound,does this point the finger towards or away from the compressor and where should my next port of call be?
I have gas in the system though it was topped up by one of those little Halfords cans by the low pressure valve only,I've been told that the low and high pressure valves need to be worked with when topping up with specific kit.
I only get the book symbol when attempting to operate the aircon and my system has no leaks.
Thanks.

engine needs to be running and click is magnetic clutch, there is a pressure switch on ac and if gas is low or switch faulty it won't run.

fanatic said:

engine needs to be running and click is magnetic clutch, there is a pressure switch on ac and if gas is low or switch faulty it won't run.

Click to expand...

So because my engine was running and I got the click this would mean my compressor is ok?

amongstit said:

So because my engine was running and I got the click this would mean my compressor is ok?

Click to expand...

Does the compressor centre turn when you get this click. It is connected by a magnetic field pulling the clutch in. You will note that with engine running outer part of clutch rotates, when clutch engages all of clutch should rotate. Compressor is switched by relay 3 supplying power to dual pressure switch from fuse 27. This switches compressor on or off dependant on internal system pressures.

If he uses a direct 12v line from the battery to test the compressor, are the pressure switches still in the circuit? Because power is no longer being sent through HEVAC ecu I would have assumed not? Been known to assume wrong before..!

rasheed said:

If he uses a direct 12v line from the battery to test the compressor, are the pressure switches still in the circuit? Because power is no longer being sent through HEVAC ecu I would have assumed not? Been known to assume wrong before..!

Click to expand...

No, if you jump 12 volt + direct to lead from compressor clutch all it proves is that magnet is capable of being activated. Does not even mean clutch will engage. Clutch is metal to metal and sits on a diaphragm which is deflected by magnet to engage, it wears over time, can be adjusted for engagement by removing shims from shaft. There was a mod on early models because of voltage drop in circuit causing clutch to slip. It will be in tech bulletins. Switching Hevac on activates relay 3 powering dual pressure switch along with rest of system.

Once again getting useful info from this group - excellent!
My P38 aircon does not work - no 12v at the red wire on the compressor - but powering the clutch directly results in the compressor working.
No cooling though, but probs because the rest of the system is not working - dual pressure switch I assume.
I guess next step is to check out relay 3 (fuse 17 and fuse 8 both OK).

This thread is a decade old! You're often best starting your own thread with your own set of problems, if the existing thread hadn't helped, then folks don't get confused with what difficulty you're having

Oops - sorry!

P38 Monkey said:

Oops - sorry!

Click to expand...

It's fine easy done!!

kermit_rr said:

It's fine easy done!!

Click to expand...

At least he used the search facility..well done that man.

tomcat59alan said:

At least he used the search facility..well done that man.

Click to expand...

Here here