Abnomral Sound after starting GMC 1991 A/C


Old 10-24-06, 07:03 AM
Thread Starter
Join Date: Oct 2006
Posts: 1
Received 0 Votes on 0 Posts
Smile Abnomral Sound after starting GMC 1991 A/C

My vehicle's details are:
1- Engine size is 454, 7.4 L, V8
2- Model 1991
3- Type GMC 2500

It is working fine. However, every time I started the A/C an abnormal sound is heared like "hummm". several checks were done and did the following:
1- Replaced the A/C compressor
2- Replaced Auto belt tensioner
3- Idler pulley bearing
4- Replace belt
5- Replaced broken mounting bracing of Power steering pump
6- Replace broken power steering pump and alternator bracket at the bottom support

However, the problem still exists. Please share your possible solutions and advices that will help me fix it.

Many thanks in advance.
Sponsored Links
Old 10-24-06, 08:18 AM
HotxxxxxxxOKC's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2006
Location: USA
Posts: 8,044
Received 0 Votes on 0 Posts
Look at the following:

1. Inspect Water Pump - Main shaft seal on water pump has failed causing shaft to squeel or grind.

2. Inspect Radiator Fan Motor - Worn or damaged cooling fan motor or circuit.

3. Inspect Alternator Bearing -Worn or damaged bearings

4. Inspect Fan Clutch -Worn, loose or faulty fan clutch.

Also, it's been so long since I replaced a a/c compressor, but, did it come with a new clutch? If not, check that out as well.
Old 10-24-06, 03:23 PM
Join Date: Oct 2006
Location: Wilmington
Posts: 4,219
Received 0 Votes on 0 Posts
You have spent a lot of money on this and still have the problem, which may not even be a problem, just an annoyance. During a cold start, there are often things in the emmissions control system that are at half settings(by the computer), that may flutter. Most of these noises go away as the engine warms up, is this your case??? If yes, stop throwing your money away, or send it to me. How many miles on this vehicle??

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes
Ask a Question
Question Title: