Lude Generation

I would like to get the air con working on my Type S as it hasn't worked the whole time I have owned the car and its the only thing on the car that doesn't work, I've never had it gassed so it could be as simple as that, I have a rough idea about how they work but never messed with one before.

What are the main things to check when diagnosing the issue, obviously I should get it pressure tested and then gassed if it holds but there's probably more things that should be checked before that, eg I know there is a clutch on the compressor that should kick in to spin the compressor when the system is switched on so that's part of it, what else?

That's about it really. Air con works on a closed loop of refrigerant using pressures and vacuums to create the cooling and drying effect. I know a lot of places add dyes into the refrigerant to aid in detecting leaks. The dyes are only really visible under UV light, so if you can get hold of a small UV torch, follow the piping as best you can shining it on all the joints etc. Also have a look at the condenser (radiator looking thing that sits in front of the radiator) as this usually bares the brunt of and stones and weather coming through the grill. Just make sure it looks pretty complete.

Remember that an acceptable loss is roughly 40-50g refrigerant per year.

Regas and go from there. I reinstalled Aircon from another Prelude in my Type S (originally mine was broke) as I removed mine when I first got it I 2007, regassed it and 4 years later is still the exact same pressure (had it retested).
Generally it's the dryer that fails of not in use for a long time.
I leave air con on permanently in all 3 ofy vehicles. Mine is set to disengage in VTEC anyway with the Hondata s300 in the Prelude.

to echo what has been said - best to leave it the AC on all the time. Not only does the gas perform the aircon function, it also contains a lubricant which when flowing through the systems keeps the rubber seals intact. When the aircon is not used, the seals dry out, and then the gas leaks out. Also having the aircon on even in the winter with hot air will hep dry out the interior of the car.

There isn't much you can do DIY. If the gas has leaked out because the seals are gone, then DIY topping up isn't going to help. Take it somewhere where they can pull a vacuum on it and then fill with dye and find the leak, then recharge it properly after the repairs are made.

The clutch will only activate when the pressure in the system is correct. Generally, if there is no gas pressure in the system then the compressor clutch will not engage. I haven't visually seen the sensor, but there is normally a 3 way sensor that senses when pressure it too low, just right, or too high. I suspect there is a troubleshooting section in the prelude workshop manual.

An easy way to check if you have any gas pressure is to remove the cap and press the schrader valve with something (not your finger), if you get a strong release, then there probably is gas. If you get a feeble emission then the system isn't pressurised.

Thanks guys, i suspect the system isn't pressurised then, will do a thorough visual inspection and check if anything in the system, then go for regass and see from there, looking forward to getting it back on the road again this year