Carl Muckenhirn

Has anyone replaced their A/C 3 level pressure switch? Seems mine has failed.

A/C compressor won't engage normally, it can be "hot wired", and all fuses and relays are ok. I assumed that the pressure was low and prepared to re-charge. When I hooked up the recharger the pressure read 25 PSI (minimally charged).

I'm wondering if the pressure switch can be changed without evacuating the system?

thanks in advance,

carl.

Adrian

Dear Carl,
The switch is easy to change but it does require the system to be evacuated. It is hard connected into the system. Caution is also advised because the expansion valve is just down the line and these lines are known to be easily disturbed and leak if you have not carried out the simple TSB on the expansion valve.
Ciao,
Adrian
964C4

PS: Just as a matter of interest what are the measured high and low pressures when you bypass the switch?

Carl Muckenhirn

I haven't bypassed the switch. Once I discovered the system is not empty (my original thought) I buttoned everything up and sent my message.

I'm not at all equipped to properly evacuate (and the pressure test) the system so its off to the wrench for a little work.

carl.

PS. My brakes are an interesting problem, after hotwiring the hydralic pump so I can safely move the car, the pump came on when I started the car (go figure). I've got the pressure switch on order hopefully that will get things back to normal operation.

(given my recent history with pressure switches, I guess I'll be replacing the differential pressure valves in the heating system next...)

Adrian

Dear Carl,
Be careful with that hydraulic pump it has got to turn off within 120 seconds max otherwise it will burn out.
I hope you do not have to change the valves in the heating system that is one dirty job.
Ciao,
Adrian
964C4

Brecktex

My '87 3.2 does not have the pressure safety switch like the 964s & 993s, and I'd like to retrofit one into the compressor clutch circuit. I'm trying to not reinvent the wheel, if possible, and would like to know how and where Porsche did it. In the 964 & 993 models, where is the safety pressure switch located ? At the compressor's outlet port, at one of the drier's ports, etc.?

Any info will be most appreciated.

Thanks,
Bill

Navaros911

It's definitely not by the compressor.
Replaced mine not long ago, just the compressor, two hoses and the clutch cable there.

It must sit elsewhere in the system. Sorry I can't be more specific. Perhaps you can check the spare parts diagram. It should be quite easy to figure out from there.

mystert

Its up in the frunk on the drivers side. You need to removed the plastic over up by the cowl that covers the AC system to get to it. Its screwed into one of the metal pipes that come out of the drivers side fender.