Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 12-14-2011, 07:53 PM   #1
Pat
Registered User
 
Join Date: Jun 2007
Location: Littleton, CO
Posts: 456
Running the heater makes the whole car shake

Today when I turned the heater on, the whole car started to vibrate/shake. I turned it off, and the shaking stopped. I turned it on and off many times, and sometimes the car shook, other times it did not. Another interesting point is that when I turned it off, it seemed to take a couple seconds for the HVAC system to "spin down," and the shaking/vibrating was at it's worse during the three seconds between the LCD saying the fan is off, and actually hearing the system stop.
Has anyone else experienced this before? What could it be? Loose bolt on the compressor? Please tell me this is an easy DIY fix.

__________________
"Of all the extreme sports I've ever participated in- windsurfing, kite boarding, wake boarding, tow-in surfing and snowboarding- skiing, for me, made everything else easy."
-Chuck Patterson

Last edited by Pat; 12-14-2011 at 07:59 PM.
Pat is offline   Reply With Quote
Old 12-15-2011, 04:27 AM   #2
Registered User
 
Join Date: Oct 2011
Location: Olympia, Wa
Posts: 370
on auto? AC compressor runs on auto mode...my car's RPM's dip for a second when the HVAC kicks on after starting
fivepointnine is offline   Reply With Quote
Old 12-15-2011, 08:04 AM   #3
Registered Boxster abuser
 
healthservices's Avatar
 
Join Date: Oct 2011
Location: socal
Posts: 1,014
Sorry, just trying to decipher if it is a engine thing or a fan thing. Does this happen with just the fan? Engine off, fan on, can it be reproduced?
healthservices is offline   Reply With Quote
Old 12-15-2011, 08:27 AM   #4
Schatten-Baum-Mechaniker
 
Join Date: Mar 2005
Location: Mississippi
Posts: 242
I'm guessing motor mount.
__________________
Tommy
2000 Boxster S
1973 914
tommy986 is offline   Reply With Quote
Old 12-15-2011, 08:45 AM   #5
Pat
Registered User
 
Join Date: Jun 2007
Location: Littleton, CO
Posts: 456
Thanks for the responses, guys. The motor mount was replaced a few months ago. It is definitely related to the compressor. I keep the HVAC on while turning on and off the compressor. It only shakes when the compressor is on.
I'm guessing the compressor is just loose or something. Where is that? Is that easy to get to?
__________________
"Of all the extreme sports I've ever participated in- windsurfing, kite boarding, wake boarding, tow-in surfing and snowboarding- skiing, for me, made everything else easy."
-Chuck Patterson
Pat is offline   Reply With Quote
Old 12-15-2011, 09:47 AM   #6
Schatten-Baum-Mechaniker
 
Join Date: Mar 2005
Location: Mississippi
Posts: 242
remove the panel behind the seats, then you can observe what is happening.
__________________
Tommy
2000 Boxster S
1973 914
tommy986 is offline   Reply With Quote
Old 12-15-2011, 10:24 AM   #7
Pat
Registered User
 
Join Date: Jun 2007
Location: Littleton, CO
Posts: 456
Fantastic! I was hoping that would be the answer. Thanks, tommy986.
__________________
"Of all the extreme sports I've ever participated in- windsurfing, kite boarding, wake boarding, tow-in surfing and snowboarding- skiing, for me, made everything else easy."
-Chuck Patterson
Pat is offline   Reply With Quote
Old 12-15-2011, 01:14 PM   #8
Certified Boxster Addict
 
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,646
My guess is that the problem is in the idle control - its not properly adjusting for the added load of the A/C.

When you turn the fan on in Auto mode, the A/C compressor comes on and extra load is bogging down the engine idle to where the car shakes. Turn off the fan (and thus the A/C) and the idle resumes to normal in a few seconds.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
thstone is offline   Reply With Quote
Old 01-03-2012, 12:26 PM   #9
Pat
Registered User
 
Join Date: Jun 2007
Location: Littleton, CO
Posts: 456
I finally got around to taking the interior engine cover off today. Everything there looks good and tight. There seems to be no play in the compressor pulley or anything else.
thstone, things seem to be pointing to what you suggested, the idle control valve. That said, the car has always and currently idles perfectly. Knowing that, do you still think it's the ICV that is the culprit? If so, is this the procedure you recommend?
Clean the Throttle Body
Thanks all!
__________________
"Of all the extreme sports I've ever participated in- windsurfing, kite boarding, wake boarding, tow-in surfing and snowboarding- skiing, for me, made everything else easy."
-Chuck Patterson
Pat is offline   Reply With Quote
Old 01-03-2012, 06:13 PM   #10
Registered Boxster abuser
 
healthservices's Avatar
 
Join Date: Oct 2011
Location: socal
Posts: 1,014
I wonder if your condenser fans are going when the compressor cycles on. If the fans do not go on to cool and lower the pressure in the a/c system, it is very hard for the compressor to compress a high pressure gas. One of my Boxsters had a dead compressor when I bought it. Not hard to replace though.
healthservices is offline   Reply With Quote
Old 01-03-2012, 07:28 PM   #11
Pat
Registered User
 
Join Date: Jun 2007
Location: Littleton, CO
Posts: 456
Hmmm...interesting. How would I diagnose that?

__________________
"Of all the extreme sports I've ever participated in- windsurfing, kite boarding, wake boarding, tow-in surfing and snowboarding- skiing, for me, made everything else easy."
-Chuck Patterson
Pat is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 08:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page