Low Pressure? A/C

[Porschekid944]

hey guys new to the forum and just here for some help like everyoneelse so my first question is, i just got this 944 year 85.5 and the a/c doesnt turn on at all, i made the assumption it was the freon and so did the seller. so i bought some R12 off of ebay got the right hose, but now my only dillema is that i dont know which is the low pressure. ive gotten word that the larger diameter pipe is low which is the farther north nozzle and ive gotten word it is between the headlight and the rest of the hood parts which is the south nozzle. can any one make some sence of this for me. and also if any one has the time to give me a quick walkthrough on how to approach this refill.

thanks a bunch

sonny

[looneybin]

The one near the shock tower, also if the compressor won't come on with the a/c switch pressed, you can jump the low pressure switch near the other port with a screwdriver.
Only do that for 10 seconds until the pressure is high enough for the system to take over

[Porschekid944]

so the farther south one? near the headlight?

[looneybin]

The low pressure port that you use to fill the system is the one next to the top of the shock (top of photo)
The low pressure cut off switch is on the side of the drier (next to the headlight, it looks like the aluminum can with the glass window on top)
Pull the cover off the wires going to the low pressure cut off switch, & with the car running & A/C on, attach the freon to the low pressure port, then jump across the terminals with a screwdriver.
you should hear the A/C compressor come on.
Start filling the system.
Only jump the switch for 5 or 10 seconds.
When you move the jumper away from the terminals, the compressor should stay on.
Keep an eye on the pressure so as to not overfill the system.
If the compressor won't stay on, even with pressure in the system, the A/C relay may be bad.
Hope that helps

[Porschekid944]

"jump across the terminals with a screwdriver" what does that exactly mean

[mattdavis11]

to create a connection through the use of a screwdriver, to bridge the connectors or terminals on the switch with a screwdriver, to connect the two electrical posts on the switch via a screwdriver. This process will not work if your screwdriver is plastic, the handle can be plastic, or rubber, but you need a real screwdriver, not a fisher price screwdriver.

[Porschekid944]

i feel like im asking some dumb questions but i got to, connection of what two electrical posts? haha what connecters or terminals

[looneybin]

the 2 electrical wires that go into the low pressure cutoff switch need to be jumped to bypass the cutoff switch.
If the A/C freon pressure is too low, then the low pressure cutoff will not allow the system to run, saving the compressor from destruction.

[GasPowered]

Just to make sure I understand (I can be pretty dense at times), you should jump the plug (to make a circuit) and not the terminals, correct ?

Thanks for the help !

Cheers

[mattdavis11]

yes, if you put a paper clip or other metal object in the female ends of the plug that will bypass the switch. Sometimes you can use a screw driver or other with the plug plugged to jump across the male terminals on the switch. Either way you bridge the connection so the switch is by passed. As said above, the switch is right there near where your lower circle is in the picture above, at least it is on my car.

[looneybin]

you don't need to unplug the switch, just pull back the rubber cover to expose the terminals

[Porschekid944]

hey guys i did what you said
took off the covers of the 2 square looking
points almost under the headlight (south of pic)
filled up through the low pressure
near the shock tower(north end of pic)
with the car running
i saw some fluid moving through the
glass view of the drier
but i dont feel any cold air yet?
any ideas? am i supposed to hear something
when i jump the terminals or maybe one
can is not enough?

thanks

[mattdavis11]

You will hear the compressor kick on. If you saw a stream of bubbles in the sight glass the compressor was most likely moving the refrigerant but you need to verify that it was the compressor, and not just the can as it was being added to the system. The system holds about 2lbs of R-12. Did you throw some dye in to help you find the leaks?

[Porschekid944]

naa i didnt throw any dye in. and i cant say if i heard the compresser kick in. i know i dont feel any change in a/c coldness.
any ideas what i should do next?

[mattdavis11]

You mean outside of putting guages on it to see the pressures on the high and low side? See if it will suck in another can. One pound of R12 isn't going to make it blow cold.

You'll know when the compressor kicks on.

[Porschekid944]

ok im proably gonna get another 2 just to be safe from ebay
and do i still have to jump the terminals when filling?
and also were can i get a guage that will fit the old r12 fittings?
and high pressure is the nozzle near the headlight correct

[mattdavis11]

You don't need to jump the switch after the first can goes in, at that point there is enough pressure in the system for the compressor to run. Yes, the high pressure fitting is near the headlight. You might try harbor freight for gauges, but I don't know if they will have them. I wasn't going to say anything about leaking r12 to the atmos. because I think it's all a bunch of bull**** anyway, besides that I don't know if you are, and it might be legal where you are, but I'd hate to see you throw cans at your a/c system only to have it all leak out overnight.

For the shade tree mech, you can get it to blow cold, but if you want it done right, you are far from it. I don't mean to sound harsh, but I know, and I think you know that there are certain steps that must not be skipped if you want a fully functional a/c that runs at peak performance. Vacuuming down the system is only one step, for instance.

I used to be exactly where you are today. Let me know what else I can help with.

[Porschekid944]

great info, like i said ill proably get 2 more cans, try and get a guage too. ill keep you updated as soon as i get them in. and thanks a bunch for all the info.

sonny

[Zero10]

If the system truly was empty then it probably also has air in it (likely for the same reason as it being empty). Go ahead and throw R12 in there, and the moisture in the lines (since the driers go bad after being exposed to air for enough time) will help to completely destroy your A/C system.

Take it to a shop with a sniffer, pull a vacuum on the entire system then charge it part-way (don't even kick the compressor on), use the sniffer to check the entire system for leaks at this point, no leaks = turn compressor on and fill the rest of the way.

Doing it any other way with R12 or R134A is just half-assing it.

That said, if you really want to do it the easy way get a hydrocarbon based R12 replacement (redtek, duracool, hc12, etc). They don't care about air or pulling a vacuum on the system, they are more efficient than R12 and they don't hurt the environment NEARLY as bad if they leak out. If you use redtek it also has a tracer added to it so that sniffers can pick it up. Duracool has flourescent dye added already to help find leaks as well. My 951's A/C is full of red tek, it blows absolutely ice cold and after finding all the leaks it has been working great for over a year now.

[The Glademister]

Originally Posted by Zero10

Duracool has flourescent dye added already to help find leaks as well.

Trying to figure out what's in my system. I can see bright green fluid and bubbles thru the dryer window. Duracool?

Also, if I'm converting to r134 I'll have to pull the valves out of the high and low side ports. What's the procedure to collect the old coolant before you remove these valves? I've got a vacuum pump and gauges so I'll be able to evacuate the system (after changing the dryer and o-rings).

I've also seen posts speaking of flushing the system. How is that fluid introduced and then extracted?

Thanks.