A/C Issues

[Samwhaaa]

Hi all,

I've been searching for some answers with no luck as yet.
The A/C clutch doesn't engage when I turn on the Air con nor do the fans in the engine bay.
I tested the relay and it is fine, I've tried jumping the relay and the clutch engages.
The refrigerant should be fine as it was regassed in April with no leaks detected.

Mechanic says they will start with replacing the compressor and then go from there but I'm not convinced the compressor is the problem.

Any ideas or ways I could test anything else would be appreciated.

 

[Fu Manchu]

There will be a wire for a trigger to operate the fans and operate the clutch. The relays can work, yes, but if there is no current from the trigger wire to tell it to do relay things, relay things don’t relay.
When you tested, you fabricated a trigger signal.

I don’t know which one is the trigger. A wiring diagram would be needed.
It’s in here: https://drive.google.com/drive/folders/1-8JJ0l9vjMjbIzCgTX8u2DFOgJAeoJjV

(No it won’t work on your phone)

All going well, someone jumps in with more info.

 

[the_boozer]

put 12 volts on the aircon clutch to bring it on and see what happens does it get cold with in 30 seconds? Is there 12 volt going to the clutch with the aircon turned on ?

 

[lout]

you need a new mechanic
most likely low on gas
see an ac specialist
it may be that the compressor has a leak
but i suspect the parts cannon is loaded and awaiting firing orders
berlina will have climate control
is it set to a level where ac should come on, ie windscreen

 

[Samwhaaa]

put 12 volts on the aircon clutch to bring it on and see what happens does it get cold with in 30 seconds? Is there 12 volt going to the clutch with the aircon turned on ?

Thanks for the reply mate.
With clutch on it does get a bit colder. Not freezing but colder.
I'll double check shortly but I think when I tested with the multimeter this morning there was definitely continuity from relay socket to clutch and there was 12v at the clutch without the car being on (clutch socket is in a prick of a spot inbetween the belt...)

 

[Samwhaaa]

you need a new mechanic
most likely low on gas
see an ac specialist
it may be that the compressor has a leak
but i suspect the parts cannon is loaded and awaiting firing orders
berlina will have climate control
is it set to a level where ac should come on, ie windscreen

Didn't try changing the setting but it was on Max cold, A/C on (and displayed as on on the dash), full fan & vent set to head?

 

[Fu Manchu]

Set to demist/windscreen

 

[Samwhaaa]

Set to demist/windscreen

Still no front fans even with the relay jumped.
also no cold air..

 

[lout]

sounds like no gas
i dont think the fans will come on if bridging ac relay
as it is a command, and you are bypassing straight to power circuit

 

[Skylarking]

I thought all older AC systems had two pressure switches somewhere in the AC line that act as a safety measure to protect the compressor and AC plumbing from damage. One switch goes open circuit if pressure is too low while the other switch goes open circuit if the pressure is too high (or similar). If either switch triggers then the AC clutch can’t engage (as the AC clutch power feed passes through these switches) and thus the compressor won’t turn. As such it won’t compress the refrigerant and the high pressure AC lines will never get hot and low pressure AC line will never get cold (thus the cabin air can’t get cold when blowing through the evaporator). An AC system will only function if it contains the correct amount of refrigerant (and oil) or the safety mechanism is bypassed (ok for doing some diagnostic test but not good long term)…

The rest of the system is electrical (and/or sometimes pneumatic) and used to control the air vanes which direct air flow through the heater core and/or ac evaporator core and to the desired cabin vent as well as the fan speed The older the car the more basic the electrical system.

(More modern cars have more clever electronics and such to turn cycle the AC compressor and control the air mix and airflow outcomes through the cabin but the refrigerant side of the system hasn’t changed much in principle other than different types of gasses and a PWM hydraulic control of the swash plate angle that means no clutch is required in some vehicles).

So if the system isn’t making cold air, the first check would be to test the refrigerant line pressures and go from there. Obviously a wiring diagram and system component view diagram would be helpful in working out how the system functions but any AC mechanic should be able to fault these systems rather easily.

Unfortunately the refrigerant side of the system isn’t something owners can legally service themselves as you need to be licensed to work with such things

At least your car used R123A so it’s not as bad as some older R12 systems that need to be upgraded (or converted to propane?)…

Go see a AC specialist as it’s the best way forward.