My rear defog doesn't stay on long enough to defrost the window. It will stay on for a few seconds, then shuts off. After that, it takes a while before it will turn back on. A search of this forum suggested replacing the 30A breaker with a 30A fuse. I did that. Still have the same problem. What am I missing here?

 

Does the fuse blow? Threads like this are usually in the general tech forum.

 

Apologies for mis-placing the thread. And to answer your question: no. The fuse is good.

 

Moving.........

 

Any chance the problem could be the rear defog switch itself?

 

Defogger should run 5-10 mins before shutting off..If if shuts off sooner the combination switch/timer is defective. If it stays on correct time but does not defrost then you can test the window grid lines with a test light. Ground light lead and probe the grid lines, should have light on all horizontal lines and light brilliance will change as you move the probe towards the center. Buy the way power seat uses same fuse , verify seat works when defog does not..

 

I don't have power seats. But the grid on the rear window works. The defrost just doesn't stay on long enough to complete its job. Short of going to GM, is there anyone that makes an aftermarket switch/timer setup for the 97's & newer? The switch is integrated with the entire climate-control setup, which I'm guessing isn't cheap...

 

I have this same exact issue...following this thread!

 

In my '94 the delay is built into the switch, sorry I do NOT have a '97 service manual.

 

On a '97, the switch is non-servicable. The parts/service Dept. at the local dealership wants $266 for the HVAC box, which includes the switch. GM Parts Direct wants $138. Autozone, Auto Value, etc., ...no one has a simple, cheap, aftermarket solution for this, apparently...

 

That's why there are junk yards and pick-a-parts......