Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Full charge but A/C compressor won't turn on

 
Old 09-07-2010, 05:59 PM
  #16  
Formula94lt1
User
Thread Starter
 
Formula94lt1's Avatar
 
Join Date: Jul 2007
Location: DFW
Posts: 373
Default

Well power at the switch was 10.6v. I forgot where to test the head unit at and cannot find the thread.

One thing that worries me is the fact that I found no volts at the freeze switch, I may have to go recheck that, as I found 10.6 at the a/c switch with the car not running but Zero at the freeze switch, but that was when the car was running...

I guess that could also mean that the switch itself is bad, how could I test this?
Formula94lt1 is offline  
Old 09-29-2010, 02:09 AM
  #17  
Speedtoys
Addict
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 9,807
Default

*bump*
Speedtoys is offline  
Old 09-29-2010, 09:11 AM
  #18  
Mrmerlin
Petie3rd
Rennlist Member

This Post Sponsored by:
Dow Corning« & DeoxIT«
 
Mrmerlin's Avatar
 
Join Date: May 2004
Location: Philly PA
Posts: 22,569
Default

did you replace the AC relay switch that is controlled by the AC switch?? if you did then it may be miswired otherwise it probably is bad
Mrmerlin is offline  
Old 09-29-2010, 09:14 AM
  #19  
Mrmerlin
Petie3rd
Rennlist Member

This Post Sponsored by:
Dow Corning« & DeoxIT«
 
Mrmerlin's Avatar
 
Join Date: May 2004
Location: Philly PA
Posts: 22,569
Default

read this found with a search of "ac relay"
https://rennlist.com/forums/928-foru...ight=ac+relay+
Mrmerlin is offline  
Old 09-29-2010, 11:13 AM
  #20  
Speedtoys
Addict
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 9,807
Default

Im 99% sure my relay is fine, fans come on with AC switch, AC switch lights up, nd on defrost the system blows on high fan.

I have about 45psi of R134 on the high and low side..but no compressor spinny uppy.

Will take the 12v feed of compressor to ground next in the next few days, if not tonight.
Speedtoys is offline  
Old 09-29-2010, 04:49 PM
  #21  
SQLGuy
User
 
SQLGuy's Avatar
 
Join Date: Mar 2010
Location: Colorado Springs, CO USA
Posts: 1,297
Default

Originally Posted by Speedtoys View Post
Im 99% sure my relay is fine, fans come on with AC switch, AC switch lights up, nd on defrost the system blows on high fan.
Based on what are you so sure about the A/C head relay? The pair of contacts in it that typically burn up don't power the fans or the blower. They only feed power to the clutch (through the freeze and low pressure switches).

You should take a meter and check for 12V (relative to ground), first at that the clutch wire (near the air pump), then at the low pressure switch (near the receiver drier - I think it's the bottom one), then at the freeze switch (under splash guard between windshield and firewall). If you don't find 12V at any of these points, then the A/C head relay (see links earlier in this thread) is a very likely culprit.

Paul
SQLGuy is offline  
Old 09-29-2010, 07:00 PM
  #22  
dprantl
Super User
 
dprantl's Avatar
 
Join Date: Dec 2003
Location: Atlanta, GA
Posts: 4,470
Default

Originally Posted by Speedtoys View Post
Im 99% sure my relay is fine, fans come on with AC switch, AC switch lights up, nd on defrost the system blows on high fan.

I have about 45psi of R134 on the high and low side..but no compressor spinny uppy.

Will take the 12v feed of compressor to ground next in the next few days, if not tonight.
45psi on both low and high side when the compressor is not running means there is not enough refrigerant in the system. Depending on ambient temperatures, you should be seeing at least 75psi on both sides.

Dan
'91 928GT S/C 475hp/460lb.ft
dprantl is offline  
Old 09-29-2010, 07:23 PM
  #23  
SQLGuy
User
 
SQLGuy's Avatar
 
Join Date: Mar 2010
Location: Colorado Springs, CO USA
Posts: 1,297
Default

Originally Posted by dprantl View Post
45psi on both low and high side when the compressor is not running means there is not enough refrigerant in the system. Depending on ambient temperatures, you should be seeing at least 75psi on both sides.

Dan
'91 928GT S/C 475hp/460lb.ft
Probably true, but the low pressure switch is supposed to close at 2.2 bar (about 33psi).
SQLGuy is offline  

Thread Tools
Search this Thread
Quick Reply: Full charge but A/C compressor won't turn on


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: