I know enough about aircon to be dangerous. I would want to get a set of pressure gauges hooked up and see what your low side and high side pressures are. A shop that works on AC should know the ballpark numbers. As far as the compressor running, you can remove the forward engine cover (behind the seats) and visually determine if the pully on the compressor is turning.
As I recall, it is always recommended to replace the dryers anytime you evacuate the system. Water is not a good refrigerant!
A more non-intuitive issue is the "blend door". It has to be working. Also, if the black foam cover is perished, you will get a mix of cold and hot air. The article linked below goes into some detail. In the 1st and 2nd pictures, it shows the levers that move the blend door. You should literally be able to see the levers move through their full range of motion as you adjust your dash temp setting from full cool to full heat. A final check would be to crimp off one of the hoses leading to your heater core. If the system suddenly feels cooler, then the blend door is probably the culpret. On the Cayman, hot water passes through the heater core all the time. The blend door just keeps it in or out of the cabin as required.

2007 Porsche Cayman S – Fixing the Air Vent Black Foam Problem

As many older Cayman/Boxster owners will know, these cars have a generic problem with the degredation of the heating and AC system such that small flecks of black foam spray out the air vents and t…

newhillgarage.com

 

Enabling AC with the button doesn't yield a click or drop in revs

I've reviewed all of your posts and nowhere have you revealed what generation (model year) your Cayman is. I suggest you put it in your signature, and before Don jumps in, do an intro post describing your car and relationship with it. Pictures are encouraged.
Now, the reason the year is important is that 987.2 models use a different A/C compressor that is always running - no electric clutch in the pulley. So you don't necessarily notice it cycling. Obviously, something is wrong since you don't feel any cold air blowing. Could be the blending door problem that @harveyf mentioned, since most 987's foam is either gone or clogged-up in the vents.

 

Sincere apologies, I did forget etiquette there.

This is indeed a 2010 Cayman S (987.2)

And Funnily enough I did remove some chewed up foam from the fan not too long ago (ie, it was rattling around and making a fan speed related noise). Now I type it out, why I didn't think "hmm wonder if that was important" is a bit alarming....

Ok sounds like it might just be normal air being routed through and the AC is working just fine? But wouldn't the compressor click be noticeable as it engages even on a 6 cylinder boxer?

 

On my 2007 Cayman, there is an Eco button on the dash. My understanding (but confirm in your owners manual) is that in Eco the AC is not allowed to turn on. So another way to maybe experiment and see if you hear/feel the compressor cutting in. That said, if you are getting any cool air at all, the compressor is working. If refrigerant charge levels are low, it might cause it to be less effective i.e. the temperature drop across the cooling coil will be less. BTW, if you replaced the "radiators" do you mean the ones in the front of the car that carry refrigerant (versus the ones that carry coolant)? If so, you would most certainly had to evacuate the system of refrigerant and then follow the protocols to refill it. Which you did. Right?

 

I haven't touched the AC gas myself. It was emptied previously (don't recall them telling me how much was in there).

I replaced the front air-con radiators yes (not the ones for coolant) as I assumed that there was a leak as I had that on a previous Cayman and could see a few glows from the UV lamp indicating a minor leak, but a leak non-the-less.

Then the garage refilled the gas for me, said they put 850g in there, which after a bit of Googling suggests might be too little.

My car is 2010 and doesn't have an Eco button. What I think is strange is that Durametric literally says "compressor running". Which I assume it would not if it was low pressure/faulty... But I haven't ran live data on a working car so maybe it does.

 

Just generally speaking, if the fill is way low, then the compressor will cutout based on a pressure switch in the system. But with a less than complete fill, the efficiency of the system will be adversely affected. If you know how much they put in and know what is considered a full fill, that difference could be your problem.
My paper shop manuals for my 928 have nice charts for the AC that show all sorts of things. For the newer cars, it is getting harder and harder to find info

 

When you refill,I assume you vacuumed down?
How low did you pull,and how long did you hold it?

 

All my blend door foam blew out a couple years ago (over a 6-8 month time frame) and my AC, heater and defroster all work just fine. I've detected no noticeable difference. Go figure.

 

FWIW there are 3 flaps. One is blend. One selects outlet location (feet, dash, windscreen) and one sets the Recirc mode.

 

I used the following webpage to help diagnose my AC system on my Jetta: Understanding Normal AC Pressure Gauge Readings

On that car, it turned out to be caused by a problem with the PWM valve that controls the compressor. VW chose the wrong size filter on the valve, causing it to get jammed. A replacement unit solves the problem, and is a low-cost fix... if you can find a shop to replace it.

I have heard that these Porsches have the same design, but maybe they used a different valve because the problems on Porsches aren't that frequent. Still, the point is, aside from the mixing door issues on the Porsche, the advice to use dual gauges is VERY important. You simply can't troubleshoot the problem without reading both sides. (I took the Jetta to a shop that only read the low-side and said everything was fine... morons.) I did the dual gauge testing and found the problem very quickly (I used a free rental kit of dual-gauges from Autozone... it's that easy).

 

And I'll repeat what @RSchwerer already pointed out. It doesn't matter what Durametric is telling you - there is NO ELECTRONIC CLUTCH on your AC compressor, it's running continuously whenever the engine is turning. The amount of pumping that is done is controlled by an electronic swash plate in the compressor that varies the stroke of the pistons in the pump.

There is no click. Not even a relay click since the compressor is controlled by a computer module designed to tell it what to do.

And as @schwinn reiterated - doing it with a quick fill can isn't going to work, nor is doing it without full evacuation of the system.

As to the dryer needing replacement - how long was the system "at air" (no refrigerant in it)? If less than a week or so, a good 30 minute vacuum with a high-vacuum AC pump should pull any moisture out of the dryer. If that isn't done the moisture will freeze in the dryer causing restricted refrigerant flow. If it was open to air for longer than that, enough moisture may have gotten into the system that the dessicant inside the dryer (same crap as in the paper envelopes that used to come with cameras and electronics) can turn to mush from the moisture - causing the same sort of flow restriction.

ALL of this would be quicky evident to someone trained in automotive AC systems who follows the correct procedures when recharging a system (including using a good vacuum pump, good gauges, and a wet-bulb thermometer.)

That sort of person with some Porsche expertise can often be found at a Porsche dealership. You might save some money doing the physical replacement of parts yourself - but it would be a good plan to leave the recharge to someone who (1) is supposed to know what they're doing and (2) you can complain to if it isn't working well when they're done.

It isn't the foam. I haven't heard of one case of the foam causing AC cooling problems, even on cars located in hot areas of the US. It usually is complaints about inadequate heat that get people replacing the foam.

We await your intro posting in https://www.planet-9.com/forums/new_members/ - please DO read the link at the top of very page of the forum about formatting photos to post here, and we do expect photos... its tradition.

And Welcome to Planet-9, the Friendly Porsche Forum!

 

re are 3 flaps. One is blend. One selects outlet location (feet, dash, windscreen) and one sets the Recirc mode.

And I'll repeat what @RSchwerer already pointed out. It doesn't matter what Durametric is telling you - there is NO ELECTRONIC CLUTCH on your AC compressor, it's running continuously whenever the engine is turning. The amount of pumping that is done is controlled by an electronic swash plate in the compressor that varies the stroke of the pistons in the pump.

There is no click. Not even a relay click since the compressor is controlled by a computer module designed to tell it what to do.

And as @schwinn reiterated - doing it with a quick fill can isn't going to work, nor is doing it without full evacuation of the system.

As to the dryer needing replacement - how long was the system "at air" (no refrigerant in it)? If less than a week or so, a good 30 minute vacuum with a high-vacuum AC pump should pull any moisture out of the dryer. If that isn't done the moisture will freeze in the dryer causing restricted refrigerant flow. If it was open to air for longer than that, enough moisture may have gotten into the system that the dessicant inside the dryer (same crap as in the paper envelopes that used to come with cameras and electronics) can turn to mush from the moisture - causing the same sort of flow restriction.

ALL of this would be quicky evident to someone trained in automotive AC systems who follows the correct procedures when recharging a system (including using a good vacuum pump, good gauges, and a wet-bulb thermometer.)

That sort of person with some Porsche expertise can often be found at a Porsche dealership. You might save some money doing the physical replacement of parts yourself - but it would be a good plan to leave the recharge to someone who (1) is supposed to know what they're doing and (2) you can complain to if it isn't working well when they're done.

It isn't the foam. I haven't heard of one case of the foam causing AC cooling problems, even on cars located in hot areas of the US. It usually is complaints about inadequate heat that get people replacing the foam.

We await your intro posting in https://www.planet-9.com/forums/new_members/ - please DO read the link at the top of very page of the forum about formatting photos to post here, and we do expect photos... its tradition.

And Welcome to Planet-9, the Friendly Porsche Forum!

I agree with most here, except:
1) A good AC specialist is usually better than the Porsche dealer who hardly ever sees an AC problem compared to the number of oil changes he does.
2) The desicant will not turn to mush unless you fill the system with water.
Long term (overnight) vacuum will boil off most all of the moisture.
If you really want to get the system back to clean, break the vacuum with a shot of refrigerant and pull the vacuum again for a few hours.

 

Many thanks for the tips chaps. Have reached out to a recommended AC specialist, not really interested in paying Porsche diagnostics for something that's probably quite generic. I used a local garage around the corner to do the refill (independent Ford dealer, unlikely to have an AC expert)

I'll post some pictures on the intro thread soon, hope you enjoy!