Vibration only when Air Con is on
Thread Starter
Advanced
Joined: Feb 2001
Posts: 79
Likes: 0
From: Brisbane, Queensland,Australia
Vibration only when Air Con is on
I have a problem that i have seen posted before but i have never seen a solution for. I have a vibration that i can feel between 2000 and 3000 revs only when the Air Con is on. I have had the gas checked and it is ok. If i hold the car in the rev range while the vibration is present and switch off the air, the vibration disappears immediately. I have checked all brackets and can not see any cracks etc
I have had this problem for 2 years now and would appreciate any help to fix it. BTW,, it's a 90 convert
I have had this problem for 2 years now and would appreciate any help to fix it. BTW,, it's a 90 convert
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: Vibration only when Air Con is on (sm90)
Sounds like the A/C compressor may be on the way out. My 87's compressor acts in a similar fashion except at a lower RPM and there is a noise in addition to a slight vibration. The A/C expert at my shop says I should replace it.
It works fine right now but with winter coming on , it won't get used as much except for de-humidifying when I turn the defogger on.
It works fine right now but with winter coming on , it won't get used as much except for de-humidifying when I turn the defogger on.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Vibration only when Air Con is on (sm90)
For the Nippendenso compressor, there's a rear brace running from the uppermost rear bracket bolt to the middle of the header. Make sure it's there. The bracket bolts to the right head should be torqued to 24 ft/lbs; the compressor mounting bolts including the rear brace are spec'd at 18 ft/lbs; and the brace at the header is 19 ft/lbs (may need to use a backup wrench on the header bolt).
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Vibration only when Air Con is on (c4cruiser)
My 87's compressor acts in a similar fashion except at a lower RPM and there is a noise in addition to a slight vibration. The A/C expert at my shop says I should replace it.
There is a TSB for '87 concerning slight vibration or "whine" from the compressor. It instructs the mechanic to install the brace that SunCR mentions.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: Vibration only when Air Con is on (SunCr)
My 87 has the older Harrison radial-type compressor on the passenger side and there is a small bracket already from the bottom rear of the compressor to the front bolt of the pass side exhaust header.
My 92 has a Nippondenso condensor but it's on the driver's side and there is already a bracket that attaches from the compressor to the center part of the exhaust manifold. When did the A/C compressor get moved to the driver's side?? 89 or 90?
My 92 has a Nippondenso condensor but it's on the driver's side and there is already a bracket that attaches from the compressor to the center part of the exhaust manifold. When did the A/C compressor get moved to the driver's side?? 89 or 90?
Team Owner
Joined: Apr 2000
Posts: 27,818
Likes: 8
From: CT
Vibration only when Air Con is on
Mine does the exact same thing. The whole car vibrates with it on. I don't use it that much really. It reeeeally sends the oil temps beyond what I like and the coolant temp in traffic(to me) is almost OH SH** level. :cheers:
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Racer
Joined: Feb 2000
Posts: 488
Likes: 28
From: Peabody MA
Re: Vibration only when Air Con is on (Jay 383)
My 91 did the exact same thing. When I put in my new motor I dug up the bracket that goes from the AC bracket to one of the studs on the mechanical fuel pump block off plate. No vibration at all - it's great!
I'm sorry I ever took it off in the first place.
-Mike
I'm sorry I ever took it off in the first place.
-Mike