Defrost relay

[Bitsyncmaster]

I have never needed to use my defrost so did not plan to design a solid state unit. But that is the last relay in my compartment still stock. Testing the OEM unit it switches on for about 3 minuets then off for about 6 minuets and keeps repeating.

Modern cars seem to just run it for 10 to 15 minuets then shut off.

I may have the dash light show when the heat is powered.

[JohnZ]

That would be a nice and clever solution, very Bitsyncmaster's style! :D

I've never ever used the defrost switch, I don't even know if it's operative... and by the time I find out, the rear window is defrosted via engine heat

[DMC-Ron]

I have never needed to use my defrost so did not plan to design a solid state unit. But that is the last relay in my compartment still stock. Testing the OEM unit it switches on for about 3 minuets then off for about 6 minuets and keeps repeating.

Modern cars seem to just run it for 10 to 15 minuets then shut off.

I may have the dash light show when the heat is powered.

Dave,
Is this a special relay in your car that provides the timed modulation? My car is a late 83, and it has a standard original Bosch relay. I have coopted this relay to run some undercar lighting. It does not cycle and works well for the underbody lighting. Also nice that it has the console indicator that reminds me the lighting is on.
Ron

[Bitsyncmaster]

Dave,
Is this a special relay in your car that provides the timed modulation? My car is a late 83, and it has a standard original Bosch relay. I have coopted this relay to run some undercar lighting. It does not cycle and works well for the underbody lighting. Also nice that it has the console indicator that reminds me the lighting is on.
Ron

The stock relay could probably be replaced by a mechanical relay. They swapped the control and ground pins with our harness and that would not permit me to use one of my solid state relays. I guess I could swap the socket pins and just use my fan relay with different software but then I don't get to modify the dash light. I need that center pin to drive the dash light.

The stock unit turns on for about 3 minuets and the off for about 6 minuets and keeps repeating that sequence. The dash light runs off the switch so you don't see that power cycle on your light.

[Patrick C]

...and by the time I find out, the rear window is defrosted via engine heat

This is precisely why the factory started making rear windows without the defrosters built in, that DMCH has for sale.

https://store.classicdmc.com/100625-rear-glass-w-o-defrost.html

[JohnZ]

That's new to me! In my "Ultimate DeLorean" the rear window would be without the defrosting stuff built in, and instead of the defrost switch there would be a cooling fan bypass switch! I think the defrosting ability may be one of the most useless things in the DeLorean....

anyway, keep on with your work Dave! Any improvement is welcomed! :wrenchin:

[Bitsyncmaster]

This is precisely why the factory started making rear windows without the defrosters built in, that DMCH has for sale.

https://store.classicdmc.com/100625-rear-glass-w-o-defrost.html

I do like the idea of not seeing that heating layout. I put black tape on the wide parts of that heater right after I bought my car.