Where to fill R134a refrigerant in '86 928S?

[MPDano]

Isn't that the dryer in the pictures? It's the cylinder with the window on top?

[psychII]

you found the dryer, but the wires you were jumpering are for the fan, not the compressor.

The low pressure switch is lower down on the dryer with a big rubber boot protecting the wires. If you stoop down in front of the car, you should see it through the grill.

my camera is F'ed up, or I would take a pic.

[MPDano]

OK, got it. Lower on the Dryer. I will look tomorrow after work.

[MPDano]

Ok, makes sense. The wires I was jumping go to a switch on the Dryer to turn on the electric fan. Will look for another pair of wires when I get home.

[psychII]

I know I'm doing a horrible job of trying to explain where the low pressure switch is - sorry.

If you are standing in front of the dryer looking down, it will be on the front of the dryer facing the inside of the front bumper, about half way down. However, the headlight bar will block it from view. So, stoop down and you will be able to access it through the grill.

Sorry again... hope this is a little more clear?

[MPDano]

Cool, my grill is off my car for now, so I should have a clear view of it.

Oh BTW, my inside controls do need to be on, correct?

[MPDano]

Found the area to jump. Yup, was easier to access through the grill area. I jumped it and the clutch engaged. I stopped there as I am sure it needs refilling and some oil. Thanks for all the advice!

[PorscheFanatic]

Does anyone know how to fill the compressor with oil? Do the lines have to be removed? If so, won't all the refrigerant leak out at that point?

I already filled my system with one bottle of R134a. I am guessing a completely empty system takes more than one bottle to fill.

thanks for your help. Excellent thread!

[Danglerb]

The oil goes in first, usually a precise amount. (I think)

The amateur AC hour must be hilarious for the pros to watch, but I suppose its another skill many 928 owners are going to have to learn. Anybody have some links to good write ups?

[psychII]

I am converting to 134, so I got the o-ring kit, dryer, expansion valve, and hydroglopic oil from 928gt.com.

In order to change the oil, the compressor has to come off the car (the lines will have to be removed). Turn the compressor upside down and dump out the old oil, and refill about 6 oz or so of the new oil. Replace o-rings and put back on the car.

Your refrig will leak out as soon as you crack one of the lines, so you will need to have it evacuated then refilled.

[MPDano]

Ok, go ahead and slam me, but I thought I would just do it and see what happens.

I installed all the R12 to R134a adapters (high and low). Hooked up the gauge, got nada pressure. Figured no pressure, no R12 inside. Hooked up the hoses to gauge to R134, opened the valve and jumped the compressor clutch. I emptied a can in and started another when I saw leakage at a coupler. Shut the engine down so I can tighten it down, leak stopped. I also heard the dryer (bolt next to high side port) leaking air. Put a 9/16 wrench to it and did 1/16 turn clock and it stopped. Now I hear another leak at the low side adapter, loosen the adapter and it stops. I took a long screwdriver to the low side air valve to see if it still had pressure and it did. Ok, I am no longer hearing any hissing (leaks). Started it back up and dumped the 2nd can in. Still not too cold air inside the car.

Shut car down, removed jumper. Figure I better to do a test drive and get it up to rpm and see if that makes a diff. Started car, turned A/C on, clutch engages fine without jumper. Drove about 10 miles, a little better but not cold.

The Gauge was reading on the Blue area centered, which was good according to the video the kit included. I do have a decal on the radiator that says 37, should I dump 1 more can in there?

[psychII]

from what I've been reading, 134 capacity should be about 80% of the R-12. So, I guess you should only put in about 30 oz or so. If you put in 2 cans, that's only 24. You should be able to get a half can in.

Are your vacuum actuators working properly? (comb and air recirc, heater valve)

did you vacuum out the moisture? That will impact performance too.

[MPDano]

I vacuumed nada. Just did what I did. Would 24 oz be enough to feel anything or does it have to be full at 30ozs?

Not sure how to test those things your asking me.

Vacuum Actuators (I think your talking about those things behind the center console): I did a lot of repairs to them before buttoning them up, but didn't test them. They sound like they are working behind the scenes.

Heater Valve: Is this the one near the firewall on the engine side? If so, yes this is new. How do I test this?

Comb and Air Recirc? What is this?

Thanks for this input.

[Danglerb]

Pretty sure every AC guy is going to tell you the same thing, "maybe" you haven't permanently damaged the AC system, but first thing to do is evacuate, flush with a good commercial flush, evacuate again and hold a vacuum for a few hours, then start over with a new receiver dryer, oil, and 134.

Are you using a set of gauges, or a can with a gauge on it? The can with the gauge has a LOT of stuff in it, oil and leak stuff, I don't think I would use it again (due to the amount of fluid it leaves in the system).

[psychII]

http://members.rennlist.com/pirtle/svc.html

read the HVAC section. Talks about 134 conversion, as well as checking the vacuum actuators.

The easy way to check the actuators, crank your car: pull the center vent. Inside is the comb flap-it looks like a comb. If it is working, it will be down. If not, it will be up. it's basic function is to mix hot/cold air based on where the selector is. Full cold, should be down blocking airflow across the heater core, or full hot allowing air to cross the heater core, and all possibilites in between. It it's not working, you will be getting hot air mixed with cold=inefficient.

The recirculation flap is behind a grate in the top of the passenger footwell. It either recirulates cabin air or brings in fresh air. If you have constant air coming out of your vents, tell-tale sign that flap is not working. or with the car cranked, feel in the hole that is in the center of the grate. If you can feel the lid, it is not working. If it is in the up position and you cannot feel it, it is working. Your AC will be trying to cool warm outside air, and loosing that battle.

If one or both of those flaps are not working, it will reduce the efficiency of your AC, along with the relative inefficiency for 134 and possible having moisture still in the system reducing efficiency even more.

Only having 24 oz should not make that much difference, but I don't know the answer to that. My understanding is that the system should have capacity, no more no less.

If all flaps are working, along with the heater valve, then there is probably excessive moisture in the system. May be a good idea to have an AC person vacuum for you and replace the dryer b/c moisture will F' it up. Then fill with refrigerant.

HTH

[MPDano]

Cool, that sounds like reasonable tests to try first before buying a Dryer. Thanks for this.

[MPDano]

I just thought of something. I bet it is working and that flap that covers the heater core is not there. I did have an extra flap and I couldn't figure out where it went. I could have sworn I felt some cold air as well as some warm at the same time, if that makes sense.

[MPDano]

The Flap has a bunch of holes in it, so I doubt this is the flap that shuts the heater core from mixing with cold air.

Part #928 573 505 03

[MPDano]

Also, found the "Drier" <---correct spelling of it on 928 Intl. It's not as expensive as I thought.

[psychII]

Originally Posted by MPDano

The Flap has a bunch of holes in...

if you are refering to the thing in the center vent, it will look just like a comb. when it is in the down position, its teeth will interlock with other teeth to form a solid cover over the heater core.

the HVAC link I posted has a partial picture of the comb and the teeth it locks with.