Rear Defroster Trouble
03-30-2007, 07:59 PM
#1
Rear Defroster Trouble The rear window defroster in my wife's '00 B4C works, but only half-***. If we push the button, it will come on... but only for 12-15 seconds (I have timed it). It shuts off way before it effectively clears the window of condensation. Then, the bastard will not come back on at all for a good 5-6 minutes.
Thankfully most days it is not needed at all. But when she needs it, it is nearly worthless.
My guess would be that whatever electrical/electronic control that times defroster use (or rather it lets the defroster get up to a certain temp and then is supposed to shut it down) is not operating properly.
What circuits/modules/controls/wiring should I look at? Where are these components located?
Thanks! (in advance)
Thankfully most days it is not needed at all. But when she needs it, it is nearly worthless.
My guess would be that whatever electrical/electronic control that times defroster use (or rather it lets the defroster get up to a certain temp and then is supposed to shut it down) is not operating properly.
What circuits/modules/controls/wiring should I look at? Where are these components located?
Thanks! (in advance)
03-30-2007, 08:43 PM
#3
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I tried a new breaker but it still kept shuting off after 20 seconds so I changed mine permenately to a 30 amp fuse with no problems. It shuts off after a couple minutes now and works great.
03-31-2007, 11:58 AM
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I've been told replacing the breaker with a fuse results in the fuse getting hot enough to melt the fuse block somewhat so I've refused to do that with mine... mine shuts off after roughly 3 minutes. I replaced it with a new 30A breaker and got a couple more minutes out of it but it still doesn't work like it used to and the CB was HOT.
I've been through three seperate HVAC modules (the card behind the button you push) without any better results. I've also gone through the Helms manual schematics and checked for loose grounds and damaged wires... still no luck. The best explaination I've ever heard is that after heat cycling over the years the wires and rear defroster grid increase resistance and cause the breaker to trip sooner. The wires were apparently undersized and did not take aging into account?
I'm considering making a test circuit with new wiring and checking to see if the problem is fixed- just a matter of actually putting it all together first.
I've been through three seperate HVAC modules (the card behind the button you push) without any better results. I've also gone through the Helms manual schematics and checked for loose grounds and damaged wires... still no luck. The best explaination I've ever heard is that after heat cycling over the years the wires and rear defroster grid increase resistance and cause the breaker to trip sooner. The wires were apparently undersized and did not take aging into account?
I'm considering making a test circuit with new wiring and checking to see if the problem is fixed- just a matter of actually putting it all together first.
