Original factory AC system.

It needs a recharge and I'm hoping it does not need a complete retrofit.

Thanks.

 

should be r134 right? Didn't they start using 134 in '93?

 

R-134a, the most common refrigerant now used. You can add R-134a yourself very inexpensively. While you will not know exactly how much is in the system, you can make it work again.

The only way to know for certain how much refrigerant is int he system is to pump it out and start again, you can get an idea by using a set of gauges and using the pressures and temps to make an educated guess about the amount needed.

Or, you can buy a simple low-pressure hose with the correct fittings and add 12 ounces of R-134a and see how well the system works.

If you try this, be very careful - I recommend that you do NOT use any R-134a that includes sealant, and most of the cans at the auto parts stores will include sealants, magic additives, etc. Use only straight R-134a with nothing added.

With the engine cold, hook up the can to the hose, then hook the hose to the low pressure fitting buried under the upper radiator hose. Crank the engine and let the gas flow into the system. Shut off the engine, disconnect the hose and replace the cap. Try the system and see if it works well.

 

Randy,

A slight correction to Wally's post (didn't think I'd EVER do that!!).

The low pressure connection on the '94 and '95 GTS's is not in that AWFUL location under the upper radiator hose. It is actually under the valence tray behind the engine, in front of the WINDSHIELD (NOT the radiator as I originally posted - stupid error, didn't check before sending!!) - on the drivers side. MUCH easier to work with when the engine is hot!!!

Also, confirming - the refrigerant in these cars is R-134A. You can get a can of ~12oz at any auto supply store, along with a "tap" to access it for either direct connection to the low pressure side, or with the hoses as Wally described. Can and tap should be less than $30, probably about $50 with the hoses.

Gary Knox
'94 GTS auto
'89 S4 manual

 

A slight correction to Gary's post - (didn't think I'd EVER do that!! )

MUCH easier to work on when the engine is cool.

 

Great info, guys - thanks.

Is this the inlet port?

If so, how do I remove that black cap - it does not seem to twist off?

 

That's the high pressure side - Inlet (low pressure) is under the plastic cover behind the air filter on the drivers side

 

134a introduced in all Porsche models in '94 MY. AFAIK, there are no onerous regulations requiring 134a cars to made leak-proof before recharging as there are (or were at one time) for R12 ... in other words, should be able to get a 'shot of refrigerant added' with no questions asked ...

 

Ah, thanks.

Gary's advice seems to be quite conflicting:

This is it:

 

So any advice on correct procedure?

Is the engine running with AC on when charging the system? Wally says to 'crank the engine' - rather than having the engine running?

 

For the low side to take the full charge from the can, you need the AC compressor running. To get the most out of the can, it helps to immerse it in hot water once the can gets cold to warm it up again.

 

OK, so that means engine running as well?

Thanks, Bill.

 

Yeah, the AC compressor is driven by a belt from the engine.

If you are doing a "top-off" rather than a full evacuation and recharge, then you need to go by pressure. Get a R134 kit that includes a low-side gauge. The pressure "target" varies with ambient temperature but usually you want in the range of 0.5 to 1.5 bar with the system running and engine at 1500 RPM. A chart from WSM vol 4, page 87-131 is attached.

It's best to do this with a manifold gauge set that allows you to check both high and low side pressures, but in this case, without this equipment, if you get good cooling and correct low side pressures, then be happy.

 

Engine ruuning, ac on, fan on full blast, there are cans of r134a only and when you connect the can you want to charge in the blue area of the supplied gauge, going to the very top of the line does not really mean colder air, just more pressure, so going to the upper mid part of the blue area is perfect
And yes the blue cap is your low side.
Supposed to cool a little here, I hope so!

 

Wow this got complicated. Low pressure side(blue cap ). Read instructions with Tap, connect can with proper tap setup (available at auto parts stores). start car, put on AC full cold ,blower at least medium, Meat thermometer in vent, run at about 1500 rpms as freon gets sucked into system. When thermometer gets to about 37 degrees your done. Shut off engine, disconnect hose, replace cap.