1971 corvette lights not operating correctly vents will not open and car will not idle properly

by ed wallace

yesterday I installed a c4 motor blower into my c3, it worked well vents opened car idle great and headlights were operable.only thing I needed to do today was find a wire harness to make the wiring secure to the c4 blower motor it has a 2 male prong connections the c3 has one. I found that part at a corvette salvage yard today,so I hooked it up so it can be secured and when I went to turn it on the vents opened and soon after closed the car had a rough idle, then pulled the headlight switch,because I felt it was a vacuum issue. WHen the headlight switch was pulled only the driverside headlight would open and close real slow, but I wouldnt let it open all the way, because I knew it would stay in the up position. ultimatley the driverside is now uo and the passengerside is closed. I proceeded to check the vacuum check valve, i blew into the single portside and the double port side and air went through both sides with no restrictions, can that be my problem

Comments for 1971 corvette lights not operating correctly vents will not open and car will not idle properly

Average Rating starstarstarstarstar

Click here to add your own comments

Jun 29, 2016
Headlight vacuum leak
by: Chris


Thank you for your submission. Your patience is appreciated while I try to answer your question. From what you have described it sounds like you have a vacuum leak or the check valve you described is bad. I have included a video from Wilcox Corvette that can help you understand what the results should be. Like I said over the phone if I could be there with you and reading the gauge it would be easier for me to tell you with absolute confidence that this was your issue.
https://www.youtube.com/watch?v=hoQ-yKzc3wo please check out this video for more help.

If the valve fails the test as described in the video replace it. If the problem still exists you will have to continue to troubleshoot the system part by part until you find the leak.

I will be here as long as you need help. With that said this is a two way street for communication so please let me know whats happening on your end.

If we have to I will write you a troubleshooting flow chart to follow so we can sort out your problem and you back on the road ASAP.


Chris Trautman
Corvette Brainiac

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Premium Corvette Ask.

Enjoy this page? Please pay it forward. Here's how...

Would you prefer to share this page with others by linking to it?

  1. Click on the HTML link code below.
  2. Copy and paste it, adding a note of your own, into your blog, a Web page, forums, a blog comment, your Facebook account, or anywhere that someone would find this page valuable.
Chris Trautman @ Corvette Assembly Plant 2019

About Us: Corvette Web Central | Owner Bio: Chris Trautman

Established in 2008 by Chris Trautman, Corvette Web Central quickly grew into one of the top leading Corvette enthusiast websites globally. 

"This website is a passion of mine, just as much as being a Corvette owner," says Chris.  He was frustrated trying to find information on the internet about Corvettes which was was not biased or influenced somehow. 

He has owned three Corvettes over the last twenty years and does not plan to stop owning one anytime soon.

Note: Some links on this page are part of our affiliate program and provide a small portion of proceeds to fund the administrative costs and to fund more product reviews.  We are not paid to perform the reviews or are we given any products for free.  

You might like these