Here is another aircon question

Just took delivery of my 1999 996. Car is a blast to drive, but woould be more comfortable,probably, if the A.C. was working. Is there a way to engage comp clutch? Not able to re-gas witout suction side drawing.

If you haven't already found a way to do it, jump a wire from the 12V jumper point in the engine bay to the electrical connector on the AC compressor. Be careful working with 12V in the engine bay, that jumper point is directly from the battery and not fuse protected. You do realize that the AC system needs not only freon but compressor oil?

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Have you checked the fuses? Any pressure in the system currently? Have you actually tried hooking up a can of R134 to recharge it?

Thanks for your replys. Yes I checked all three, maybe four fuses, all intact. When I tried to recharge initially I think the gauge registered over 150 p.s.i. Not sure if my memory is as good as it used to be. Any ways I blew to atmosphere all but twenty pounds of pressure. Thought maybe too much pressure in system. Been awhile since I tried to recharge any system. I tried to recharge , brought system up to forty p.s.i., but no compressor clutch action. Thought I could short across limit switch , but thought I should ask you guys first.

Something is not working in the system because 40psi is definitely high enough to close the low pressure sensor so the climate control should activate the compressor.

Ahsai, Thanks for your reply. I think you are correct. Comp clutch not getting 12 volts to coil or coil is bad. Don't have a manual or a durametric yet so thought I would ask the list about how you guys would go about energizing comp. clutch. Can't find any relays in fuse box or anywhere else in and around the car. Maybe someone will chime in with a tried and true method or some expeerience with thier own car. Thanks everyone...

Check and/or replace this relay located in Relay Support 2 underneath the carpet on the rear ledge Like I said, a simple jumper wire to energize the compressor clutch will tell you if the electromagnetic clutch engages. That will bypass all the other fuses and relays. You can do it even if the engine is not running. If it engages with direct 12V, your problem lies elsewhere.

DBJoe, Appreciate your posts. I will energize clutdh on compressor and see if it pulls in. Unfortunately your photo is not viewable on my old computer. Will check my smart phone and see if viewable from there. sounds like the relay is behind back seats? Will check.

Yes, behind back seats. Relay S4 as shown here

DBJoe, Got your last message. Was able to view on my smart phone. I took the initiative and removed air filter housing, cracked oil fill flexible joint. must have been baked out at least that is my story. Located wires going to clutch and gently pulled on one and found that it had been cut. looked like varmit bite. Was the one going to spade connector housed in plastic holder and wire tied to 12 volt supply cable. Used butt connector and solder along with shrink wrap to fashion a fix.Will let you know outcome.

First off thanks to DBJoe996 and Ahsai for thier responses. I met with success after finding and repairing power lead to compressor clutch coil. A.C. blows cold, but may need to be topped off as pressure on low side below what ambient and gauge recommended. Will use 134A with oil when topping off. Although my fix didn't require my accessing the relays, that was great info for future use. Again thanks for all the responses.

Glad to hear you got it sorted. However, if it's blowing cold, I would not recommend topping it off unless you know for a fact that the refrigerant is low. Overcharging will make the a/c blow less cold and put excessive stress on the whole system. If you really want to, I would recommend letting a shop do a full vacuum and refill to the correct amount.

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Another great post by Ahsai. I swear, a man could just about own/operate and enjoy a 996 just from Ahsai's posts alone. Got to love this forum!

Thanks! Always glad to help!

Ahsai, Will take your advice and not add any more refrigerant. Plenty cold enough, especially on the LO setting. Too cold. One other question: My key battery only lasts about a week, anyone else have and or sorted out that problem? Please let me know a fix if there is one. Thanks as always.

I've read that it's likely the circuit board has developed cracks on the solder joints. You can try to visually examine it and clean it first. If that doesn't work, you can try to resolder all the joints (surface mount).

What do you mean your key battery only lasts a week? FYI, if you don't use your car for a week, the key fob will not work, it is shut down to conserve battery power. You have to use the key in the door, then the fob will work again until it sits undisturbed for a week, then the fob will not work.