Aircon works GREAT..... for 10 minutes.....

[Millenium7]

Essentially the aircon works really well after the cars been sitting for at least a few hours, and it'll work for around 10 minutes give or take with no reduced performance at all, its really cold. But then it just totally stops blowing any cold air. Very rarely it'll start blowing cold air again if I keep on driving after an indeterminate amount of time but usually it'll only go cold if I let the car sit for a bit.
So i'm thinking maybe its the electromagnetic clutch or something else thats getting hot in the engine bay and just kills the A/C system. I don't think its a refrigerant leak because the aircon is not performing rubbish when it works, it's awesome and will cool the cabin right down on a stinking hot day within 5 minutes or so

What are the things I can check and how do I go about checking them?
If this is likely to be a part I can grab from a wreckers and slap on myself without involving an A/C shop i'm all for it

[Millenium7]

Ok so had pressures checked, they're totally fine so its definitely not a leak. What to check from here?
I'd rather not take it to a shop and pay them an hour or 2's labor just to dick around if I can instead buy some parts from a wreck and replace them cheaply in an attempt to sort it anyway. I just don't know about A/C systems and what is user serviceable

[AQUAR]

Maybe as a first point of call - check the belt tension.

[Millenium7]

I would surely hear it squeaking away if it was loose though wouldn't I?

[leadfoot6]

Yes, I think you would probably hear some squealing if the belt was loose.

To be sure, turn A/C on with the bonnet open.....listen.

Do you know if your fan(s) are operating?

When the car is idling with A/C on, can you hear the passenger side fan(the one that is for the A/C operation) turn on and off?

If your fan is not working, I can tell you how to test it to see if the problem is the fan itself, or possibly elsewhere.

Have you checked your relays in the engine bay fuse box(next to the battery)?

[leadfoot6]

Beyond some basic troubleshooting as above, my knowledge of servicing A/C systems is quite limited.

The following site suggests that your problem may be more involved and need equipment not normally owned by the "amatuer".

Troubleshoot Air Conditioning

by Larry Carley copyright 2019 AA1Car.com

[.....]

AIR CONDITIONER PROBLEM: INTERMITTENT COOLING

An A/C system that blows cold air for awhile then warm air is probably freezing up. This can be caused by air and moisture in the system that allows ice to form and block the orifice tube.

Evacuating the system with a vacuum pump will purge it of unwanted air and moisture. Evacuation should be done with a vacuum pump that is capable of achieving and holding a high vacuum (29 inches) for at least 30 to 45 minutes.

For best performance, an A/C system should contain less than 2% air by weight. For every 1% increase in the amount of air that displaces refrigerant in the system, there will be a corresponding drop of about one degree in cooling performance. More than 6% air can cause a very noticeable drop in cooling performance, and possibly cause evaporator freeze-up.

Air can get inside a system through leaks, by not evacuating the system prior to recharging it, and/or by recharging the system with refrigerant that is contaminated with air. Recovery equipment can suck air into the recycling tank if an A/C system contains air or if the system has a leak. For this reason, the refrigerant recovery tank on recycling equipment must be checked and purged daily. On some equipment, this is done automatically. But on equipment that lacks an automatic purge cycle, tank pressure and temperature has to be measured and compared to a static pressure reference chart.

Some refrigerant identifier equipment can detect air in the system as well as other contaminants. An identifier should be used to check the refrigerant before the system is serviced to prevent cross-contamination of recovery and recycling equipment.

Possible causes of intermittent cooling in a manual A/C system that might be caused by an electrical problem include:

Faulty low pressure cutout switch. This switch prevents the compressor from running if the refrigerant level is low. If the cutout switch is not reading correctly, it can prevent the compressor from coming on.

Faulty compressor clutch. The magnetic clutch on the compressor requires full battery voltage to engage. If the voltage to the clutch is low, or the clutch coils have too much resistance, or the air gap in the clutch is too great, the clutch may not engage to drive the compressor.

Faulty compressor clutch relay. Check to see if the relay is receiving voltage when the A/C is turned on. Also check the relay wiring and ground connections. If bypassing the relay with a jumper wire or routing battery voltage directly to the compressor clutch makes the A/C work, the relay is probably bad.

Faulty A/C control switch. The switch may be worn and not making good contact when it is turned on.

Some possible causes of intermittent cooling (or no cooling) on automatic A/C systems include all of the above, plus:

A problem in the control module or control head (this usually requires using a dealer scan tool to read fault codes and perform self-diagnostics).

A bad temperature sensor (an ambient air temperature sensor, interior air temperature sensor, evaporator temperature sensor, or sunload sensor). Again, a factory scan tool is usually required to perform diagnostics on the system.

[.....]

https://www.aa1car.com/library/ac98.htm

Best of luck.

Please advise what fixes your problem(s).

[Millenium7]

Well I've tried nothing and I'm all out of ideas

I don't think it would be freezing over because I can turn the entire system off for 40 minutes but keep on driving with the windows down, then attempt to start it again and still nothing. I'd imagine it'd thaw out and work again for a while

Its probably not a relay because I swapped it around with a fan relay. Both fans are on yet AC stops so very unlikely a bad relay. It almost seems heat related because I'm noticing the AC cut out sooner now that it is leading into summer. And it refuses to work if the car continues driving but if I park it for a couple hours it'll work again, briefly

Temp sensor, maybe but again unlikely due to the above. Does the AC ever fully turn off in these cars assuming it's running correctly? My understanding is it runs continuously unless in Eco mode whereby it cycles. Otherwise the climate system keeps the AC on but varies the fan speed, fan direction and heater core involvement (I.e even setting it to 32c the AC still runs but the heater is also on). But I could be totally wrong about that

[AQUAR]

There is more to the Aircon Control than just a relay to switch the clutch mechanism and a temperature sensor.


I don't have a third gen, but as a guess there must be some sort of logic controller with more than just a temp sensor (eg vacuum sensor!).
If anyone has a manual this might help pinpoint other things to look at.

[Millenium7]

OK I think its got nothing at all to do with the A/C system and is infact an engine issue. I noticed the temps seemed a bit higher than usual and sure enough as I watch the temp rise over time the A/C cuts off after it gets to a certain point. And when I stop the car I can still hear coolant in the radiator boiling after 5 minutes, so the engine is getting very hot. The question now is why...... Fans are running just fine so its not that
First thing is i'll check the coolant levels once it cools down and bleed it, could be as simple as an air bubble in there. Spark plugs were replaced not long ago but i'll look at them and see if there's anything obvious

[flyboy]

Always start with the simple stuff with cooling system. If it’s full, new genuine radiator cap next.