shadow993

My a/c was running a little warmer than Normal, so I checked the pressure. It showed 30lbs and 250lbs

Based on the outside temp and chart it should be about 50-55. I drop a can in and it barely moved from 30. So I drop another can and it goes to 40. Now the problem... highside shot up to 450 and the compressor kept turning off. Classic over charge. So I let Freon out until the compressor wasn't turning off frequently.

Now it reads 33 low and 350 high with air in vent reading 20F with outside temp 96.

It all works now , but what has me worried is nothing matches the r134 chart or anything I've read.

Thoughts on issue?

jimbo3

Your pressures are WAY too high. The spec's on the can aren't Porsche factory specs. You're lucky you haven't had a blow-out or created a leak. Yet.

NC TRACKRAT

"...with air in the vent reading 20F with outside temp 96". Whoa! That sucker could keep ice cream frozen like a brick! Sure about that reading? 50F would be more like it.

shadow993

Positive!!! I double checked

shadow993

Thanks!


I'm letting Freon out. I was using the standard R134 chart. Why does porsche always take a different path?

shadow993

26.5 after letting Freon out

griffiths

Need some clarification:
Are you meaning you had a refrigerant service gauge set connected to the system, engine running, you have a low side of 30 psi and a high side of 250 psi?
Was this at idle?
What was the outside are temperature when you observed this?

shadow993

Yes.... I had ref. Service gauges with car at idle and 95 degrees outside with mild humidity.

I think it's possible a stuck/blocked / bad expansion valve.

It registered 28-30 when .... if I dropped it to 19 as mentioned above ... I think it would get hot. It's sitting at 30 low and 250 high now. It cools properly.

griffiths

"I think it's possible a stuck/blocked / bad expansion valve."
I would not put that on the top of the list as a suspect.

"at 30 low and 250 high now. It cools properly."
If that is at 95F ambient around the car then you are doing quite well.
The low side of 30 psi "suggests" an evaporator core temperature about 32.5F.
If it was 95F ambient at that time and you have 250 on the high, you are doing quite well.

Before you go topping off or adding refrigerant to attempt to fix a "little warmer than normal" problem, always look at your P&T's (pressures and temperatures),
see if the condenser fan is operating properly, the HVAC flaps are in their proper position.... just for starters.
And, consider what "ambient 95F" you are observing: cell phone weather report, the thermometer on the house, or the average ambient around the exterior of the car.
You can have a 95F ambient standing on the grass however a 110F ambient rising off the black top under near the front bumper.

shadow993

Thanks for your help.

Don Magee

Why does Porsche use such a low charge pressure? Most cars I know of use around 35-45 PSI. Can someone educate me on this?

shadow993

Based on what I'm reading here... it says 2k RPM's which might change the pressure.

https://rennlist.com/forums/993-foru...diagnosis.html