Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

AC High Side and Low Side Pressures

 
Old 07-10-2018, 05:17 PM
  #16  
Speedtoys
Addict
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 9,910
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Andre The Giant View Post
I remember checking that last year and the liquid was creamy with no bubbles, haven't checked this year. It's doing the same thing as last year and the year before.
I will have to check for leaks when I store it, right now enjoying the drives. I do have one of my vents (comb flap I think) which is not operating like it should but the rest are fine. I also have to check my recirc vent, which I have no idea what to look for and where ?

https://www.google.com/search?q=pors...hrome&ie=UTF-8
Speedtoys is offline  
Old 07-11-2018, 11:33 AM
  #17  
Eplebnista
Addict
Rennlist Member
Thread Starter
 
Eplebnista's Avatar
 
Join Date: Jul 2011
Location: Millersville, MD
Posts: 1,292
Likes: 0
Received 0 Likes on 0 Posts
Default

Thank you all for your input and the reminder to check pressures with RPM above idle. She Who Must Be Obeyed and I took a nice Sunday drive to experience some of Maryland's covered bridges in the Catoctin Mountains. The AC was deemed to be working at the required level and I have not touched it.

Andre; It is my understanding that the chart you found, which is pretty much identical to the one I use, is derived principally from the qualities of the particular refrigerant and the immutable laws of thermodynamics rather than the characteristics of a particular vehicle. The WSM chart is better, but the generic chart will get you in the ballpark. If I am wrong about this, I hope someone will chime in.
Eplebnista is offline  
Old 07-11-2018, 03:15 PM
  #18  
Andre The Giant
Addict
Rennlist Member
 
Andre The Giant's Avatar
 
Join Date: Mar 2014
Location: Gatineau, QC
Posts: 807
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Eplebnista View Post
Thank you all for your input and the reminder to check pressures with RPM above idle. She Who Must Be Obeyed and I took a nice Sunday drive to experience some of Maryland's covered bridges in the Catoctin Mountains. The AC was deemed to be working at the required level and I have not touched it.

Andre; It is my understanding that the chart you found, which is pretty much identical to the one I use, is derived principally from the qualities of the particular refrigerant and the immutable laws of thermodynamics rather than the characteristics of a particular vehicle. The WSM chart is better, but the generic chart will get you in the ballpark. If I am wrong about this, I hope someone will chime in.
Thank you Otto and everyone.
Andre The Giant is offline  
Old 07-11-2018, 08:09 PM
  #19  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 17,857
Received 1 Like on 1 Post
Default

The description of “creamy with no bubbles” is contradictory. The refrigerant stream is clear with thin slivers of oil in the liquid. “Creamy” is the same as “large fraction of entrained vapor”, technical language for “bubbles”.

While it it might be simple to just add refrigerant until there are no bubbles, the mass of refrigerant needed to get there varies widely as ambient and cabin conditions change. We use gauges to monitor system conditions against those ambient conditions. High condenser pressure can point to poor airflow, high ambient condition In both the cabin and outside. Suction pressures are determined by compressor performance as well as by charge mass. Along with cabin temps and humidity, fan speeds, and a properly functioning expansion valve. A perfect system has suction pressures low enough to freeze the evaporator, generally less than 30 psig. There’s enough condenser performance and airflow to get liquid to the expansion valve at the lowest possible condensing pressure and temperature. Easy to do when it’s cool outside. So testing pressures while it’s 70 and seeing bubbles at 1500 rpm tells me there’s air in the system, it’s undercharged, the compressor isn’t working well, perhaps the expansion valve is sticking. The Big Test is whether you can keep your fun barometer cool and happy on a hot day in Hell.
dr bob is offline  
Old 07-12-2018, 02:38 PM
  #20  
worf928
Addict
Rennlist Member
 
worf928's Avatar
 
Join Date: Oct 2003
Location: New England
Posts: 12,143
Received 2 Likes on 2 Posts
Default

Section 87-116;117


worf928 is online now  
 


Thread Tools
Search this Thread
Quick Reply: AC High Side and Low Side Pressures


Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: