AC high pressure switch replacement

[Efren]

I’m having issues with my AC. New rebuilt compressor from 944online. It was working well for couple weeks then all of a sudden it barely worked. I did a lot of search I clouding picking Tom’s brain and resources. Tom helped a lot on trouble shooting my system. A lot of pointers from him and his documentations.

My primary issue is it’s not blowing cold air. Sometimes it does and most times it doesn’t. When it does work cold air only works when it’s on low or #1 setting on the fan knob. I did take it in to have it evacuated and recharge and it checked out good. No leaks.

I did some YouTube search and found my symptom is one of the cause of a bad AC high pressure switch. This was a YouTube video on a GM and Chrysler they described the symptoms I was having.

My question is if I take out the old high pressure switch will the refrigerant discharge? From The way it looks it will discharge.

Appreciate any feedback
Thanks

[Tom]

I’m having issues with my AC. New rebuilt compressor from 944online. It was working well for couple weeks then all of a sudden it barely worked. I did a lot of search I clouding picking Tom’s brain and resources. Tom helped a lot on trouble shooting my system. A lot of pointers from him and his documentations.

My primary issue is it’s not blowing cold air. Sometimes it does and most times it doesn’t. When it does work cold air only works when it’s on low or #1 setting on the fan knob. I did take it in to have it evacuated and recharge and it checked out good. No leaks.

I did some YouTube search and found my symptom is one of the cause of a bad AC high pressure switch. This was a YouTube video on a GM and Chrysler they described the symptoms I was having.

My question is if I take out the old high pressure switch will the refrigerant discharge? From The way it looks it will discharge.

Appreciate any feedback
Thanks

If you suspect the pressure switch, you can unplug it and jumper the connector in lieu of the switch to see if that changes anything. However, I'm 98.B47% sure the pressure switch works by turning off the compressor -- so I'd only suspect the pressure switch if the a/c clutch is not staying engaged when you think it should be.....

PET shows an o-ring for the pressure switch. While I've never removed one with the system charged, I would have to believe you'd be letting the freon out if you removed it without evacuating the system.

[AudiSport]

Was the system charged and tested with the engine at operating temp? Sometimes they can be filled with the engine cold, then when the car is hot, the pressure is too high and then you hit the high pressure switch turning it off.

Get a gauge on the system with the car at temp. It could be overcharged.

[Efren]

Thanks for your feedback. I went ahead and made an appointment with a shop that specializes in AC system.

[Efren]

Was the system charged and tested with the engine at operating temp? Sometimes they can be filled with the engine cold, then when the car is hot, the pressure is too high and then you hit the high pressure switch turning it off.

Get a gauge on the system with the car at temp. It could be overcharged.

Thanks for your feedback. I went ahead and made an appointment with a shop that specializes in AC system.
I don’t have a gauge but what I do notice is when turning on the AC usually the fan automatically comes on high once you turn in the AC. In my case the fan is working JT at a very Low speed. This is why I suspect the high pressure switch. From research via YouTube non Porsche. It was mentioned that if I have a bad switch it can cause the issues I’m having.

[Efren]

Update on my issue.
Took the car to Radiatorland. They specialize in AC and radiators. The tech there has over 30 yrs experience on AC system and the owner is a 911 SC owner.

They Evaluated the system and charged it up but the high pressure side was low on pressure. They found the expansion expansion valve to be the culprit. This is when they called me to explain the situation.

According to their estimate they would need to remove the HVAC unit and in order to do that they need to remove the dash. This is according to their manual they they use for reference. They quoted me over 2k to do the job. Told them let me think about it and I automatically did a search on Expansion valve replacement. I found an post from 2010 on Rennlist and another on Pelican. Both post states you can access expansion valve directly from the hood where the blower motor sits.

I showed the post to the owner. He’s familiar with Pelican and Rennlist. He said they’ll give it a shot using this method. 5 hrs later car was done.

[Efren]

Note
The Thermometer temp was at a stop. While moving it was 50 deg

[Tom]

Awesome! The FSM does indeed say the HVAC unit needs to come out, but 944 people have learned better over the years. It's still a hassle, but you saved your interior from a ton of unnecessary disassembly, and who knows how many brittle old plastic pieces would have snapped in the process. Nice work. Enjoy the cool air.

[Efren]

Thanks Tom. Very happy with the results. I was thankful they were willing to go by the Rennlist post. Not sure if other shops would even attempt that.

[tubegearhead]

Is there a DIY tutorial on replacing the expansion expansion valve? If so, please post.