Heater vent control problem

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Dec 30, 2012 | 06:37 PM

tcom98

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Cruising

Joined: Jun 2012

Posts: 14

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Heater vent control problem

I have an 88 C4 that has a heater control problem. The heat blows out of all vents all the time. I cannot direct the heat to just the floor or just defrost etc. I do not believe the problem lies with the heater control itself as I have taken it apart and thoroughly cleaned all of the connections and buttons. The lights indicate the head it set to whichever button I push but the air always blows out all vents. I would appreciate any input to point me in the right direction to troubleshoot this problem.

Dec 30, 2012 | 07:36 PM

rrt898

Burning Brakes

Joined: Oct 2010

Posts: 1,037

Likes: 28

From: Montclair New Jersey

I have a 1986 and had the same problem. It was a vacuum diverter valve and two vacuum lines were cracked. I don't know the differences between the years but; this fixed my heat problem.

good luck

Dec 30, 2012 | 07:38 PM

tcom98

Thread Starter

Cruising

Joined: Jun 2012

Posts: 14

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Quote:

Originally Posted by rrt898

I have a 1986 and had the same problem. It was a vacuum diverter valve and two vacuum lines were cracked. I don't know the differences between the years but; this fixed my heat problem.

good luck

Thanks for your response. Can you tell me where the vacuum diverter is located?

Dec 31, 2012 | 08:52 AM

AGENT 86

Team Owner

Joined: Jan 2003

Posts: 20,306

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From: Summerland B.C. Canada

The check valve is near firewall and driver side of distributor. Follow the vacuum line from plenum, backwards towards firewall and you will find it.

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