mpillow13

Does anybody know on Denso compressor, which fitting is low pressure one- the one facing the rear of the car or the one to the right side of the compressor facing the right side of the car. AC system periodically leaks freon. Lasted about 1 and 1/2 years after last recharge. Cools fine and then one day- nothing but hot air. Compressor seems to be working fine. Planning to update to r134, kit - $40 including freon, fittings, guages etc. or updating fittings and trying hc12a (autocool-refrigerants.com). Any advice would be greatly appreciated.
Mark
91 C2 coupe

Drew_K

I just recharged my freon tonight, and the low pressure fitting was the one facing the rear on my 964. Mine is converted to R134, but I imagine the compressor fittings are in the same location. Also, I believe that the low pressure hose on a recharge kit will ONLY fit on the low pressure compressor fitting. The plastic cover also had an "L" on it, denoting low pressure. Yours may have the same.

Just remember to turn the engine on and turn the A/C to max before adding freon. Otherwise the gauge won't read accurately.

Drew

darth

I believe the low pressure side is the larger diameter hose. I've replaced all the seals in my system so it's completely empty. Do I have to jumper the compressor to override the low pressure switch when I start filling the system with R12 or will the pressure from the refill can create enough pressure to trip the pressure switch and in turn, turn on the compressor. What pressures readings should I see on the hi and low side when the system is full or should I just add four 8oz cans to bring it up to the indicated 32.8oz capacity? Can anyone post the graph of pressure vs. temperature from the Porsche manual? Since I've had the system open to replace the seals and repair the condensor do I need to bring it to an AC shop to have it evacuated? I plan on checking if it leaks prior to refilling by either pressureizing it with compressed air or a vacume. Since I've had the system open for over a week I've plugged up everything so no moisture gets in, including the dryer. When I opened the system it still had a whisp of R12 left in it so I can assume it was still relatively closed to the outside environment and moisture. Is there a way I can tell the dessident in the receiver/dryer has no moisture in it - I was thinking of putting it in a low heat oven to dry out any moisture that may have entered. I use to do this when I worked with electronic equipment where we added a dessident bag to all equipment to capture any moisture. The chemical in the dessident I think, was copper sulphate became blue in color when it was retaing moisture and opaque after it was put in a low heat oven to remove the moisture. Any other advise on recharging the system is welcome. Sorry millow13 for hijacking your thread with so many other questions but I thought you and others might be interested in the replies to my questions.

Thanks in advance
Bill
90C2

springer3

The can pressure should activate the low pressure safety shut-off.

Charging by total weight is the preferred method for filling the system. Test gages get you close, but you are spot-on if you get the correct weight charged.

The system needs to be evacuated. If it has been open, it needs to have vacuum held for an hour or two to help pull out any moisture that entered.


If you find one, let us know. I have always replaced the receiver/dryer any time I opened an AC system. Perhaps I am too conservative in this regard, but the dryer is cheap enough, and good insurance to protect the investment in the system repair.

Be sure to give the system a good flush to get contaminants and any remaining oil out. Use Ester oil - it is compatible with both R12 and R134a. Even if you are charging with R12, it pays to be ready to switch. Where are you getting R12?

Good luck

darth

I had the R12 leftover from a few years ago.

Thanks for the response
Bill
90C2