hb4

Running the A/C somewhere north of Vacaville, noticed 'smoke' coming from center vent, then realized it was fog. Shut off the A/C and saw 'dust' coming out. Later, wasn't getting much cooling so shut it off again and here comes ice flecks! And cool air, at least until the ice on the evap melted. Turned it back on, and cooled great for a half hour or so, and then it happened again. Rinse and repeat for the rest of the day, off and on, sometimes accompanied by fog.

I think the A/C was on low speed and know the the rear A/C was off. OSA in 70s.

Normal, indication of a problem? Sensor location?

Otherwise, the A/C worked great, and I remembered a trick that Jim C told Tom M about cycling the A/C off and on to melt the ice. Did that through Oregon the second day.

MainePorsche

Antifreeze switch is located under the black cowl when you lift the hood. It is about midline. It has two wires to it and a capillary tube that disappears in to the bulwark. You should note a small clip with a screw holding the tube in place. The antifreeze switch will shut down the compressor when ice build up is sensed. Easy to replace.

911 Crazy

On my shark my girlfriend would say, "looks like you blew the turbo!"

hb4

Actually, there was a perverse pleasure in seeing those ice crystals flying into the cabin after all the work I did on the A/C last year.

Fussed around with that sensor when I had the blower out for the recirc diaphragm. Maybe it came out when I was trying to stop the wiper mechanism from attacking the feather cowl. Not sure how that thing (the cowl) is supposed to fit under the two clips so I held it up with a piece of foam over the washer reservoir.

dr bob

The freeze switch is a consumable part. The fluid in the cap tube expands and contracts in a copper/brass (brass is mostly copper anyway...) bellows inside. The expanding bellows works a micro-switch to open the circuit to the compressor. The bellows work-hardens with use, eventually resisting the force of the fluid inside. Failure mode is usually 'expanded' so the compressor still runs, but the anti-icing capability is lost. Replace with new, they aren't expensive last I looked, and they do help with the in-cabin snowstorm problem in more humid climates.

hb4

Thanks, Dr Bob
I'll give it a try; still not sure how far/where it should be placed within the evap.

MainePorsche

From what I remember after my blizzard and switch replacement, I placed the capillary tube as far as it wanted to go through the aperture in the bulwark. Has worked fine ever since.
It does not retard crystal formation as designed, for example if you have the AC on and you drive into a dramatic weather front change (ie sudden thunderstorm/downpour with high ambient humidity and a mist from the driving rain on the blacktop). I had the new switch in and within seconds of this type of external weather I got fog through the vents. Only time since the replacement two years ago.

jcorenman

Bill,

There is a guide tube for the capillary, you can see it if you peak into the evaporator under the cowl (pull back the rubber seal between blower and evaporator housing). Push the capillary tube into the guide tube until you see/feel it touch the evap fins, and then another inch or so into the evaporator, between the fins. It will run up against one of the freon tubes and stop-- anywhere in there is fine.

It is also adjustable, a small screw on the side of the switch housing. I think it is clockwise for warmer (less freezing), I'll check my note on the shop wall... In our more typical climes you should see the compressor cycling on and off after a couple minutes running.

Cheers, Jim