Think I *may* have a very slow leak in my AC unit. While the unit still blows cold, it's not as cold as when I first got the car in 2007. Would like to start with a basic off-the-shelf recharge DIY to see if that solves the problem (fingers crossed) or whether a more in-depth probe of the system is required by an experienced professional.

A few NooB AC questions, please:

1. Where in a 993TT is the low side service port located?

2. Is it true that the recharge kits only fit the low side port so I can't accidentally confuse it with the high side port?

3. Have read in the RL forums that one must be careful not to overcharge the AC system. What's the best advice for a DIY recharge in terms of not putting too much freon into the system?

Going to be spending the full day in the car this Saturday and the weather's going to be in the mid-90s. If I can get my ice cold (for a 993!) AC back with a simple recharge, it's worth the attempt.

Appreciate any and all suggestions.

 

To get the pressure right,it's best to buy a manifold gauge set that reads the high and low side the same time. Both ports are by the compressor and are different sizes to prevent mix up. If I recall, low is 10-20psi and hi is 175-250 depending on ambient temp.

 

have a read of https://rennlist.com/forums/993-foru...diagnosis.html

 

At the compressor, there are 2 plastic caps (unless one we lost) covering the service ports.
The larger diameter port is the HIGH, and it is usually on the 'high' side (outlet side) of the compressor manifold
or the refrigerant line of any model.
The smaller diameter port is the LOW. and it is usually on the 'low' side (inlet side) of the compressor manifold
or the refrigerant line.



You are probably discussing the R134 "Retail" DIY refrigerant cans with a hose and a gauge on the can.
The coupler on the end of the hose should only fit the LOW side service port.
If for some odd reason you find it fits both, that would be odd for R134a because of R134a systems are distinctly designed so you won't mess up.
For a DIY you only want to charge through the low side.

It is easy to overcharge any brand vehicle if you do not know the basics.
For example, knowing how much the factory recommended amount of refrigerant needed is very valuable.
If you cannot find the factory refrigerant information decal on the car you can refer to the factory shop manual,
such as section 8, which states 840 grams or 29.63 weighted ounces.
The most accurate way to know if you overcharged a system, or more importantly when the pressures of a system are too high is with gauges (low and high) attached to the system.

"Worth" in terms of time or money, or both?
The way things are normally done are:
1) Check system pressures, HVAC components (vents, flaps, temps, fans, etc).
2) If system pressures suggest the system is low on refrigerant, locate the source of leak and repair.
3) Fix leak, evacuate, charge, test and re-evaluate.
Steps 1-3 above is the way the pro's do it. The least expensive route overall in the long run.