Rear defroster not getting warm ??

[mustang_zc]

Hi guys,

I have a ecoboost s550 Mustang but it seems like the rear defroster is not working properly. Even after been switched on for more than 20 mins, I don't feel a sign of warm coming from the rear defroster. I touched it with my hands and it was cold. Is that because the outside temperature is cold (30 F) ?

I haven't got any frost on the rear window recently so cannot test it using the most straightforward way... But should it be at least warm ?

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[jasonstang]

It does not get warm.
It's only warm enough to melt snow/ice.
You are not trying to cook with it.

 

[Cobra Jet]

Go to this link, once there scroll down to middle where it discusses how to test the defroster grid with a volt meter or test light:

https://www.frostfighter.com/defroster-repair-fix-it-guide.htm

Also, check the tab connections to the glass (if visible), found on the outer vertical grid lines. If one tab has detached from the grid or glass then the electrical circuit has been broken. The same is true if one of the harness connectors to the tab has become loose or fell off.


Another way to test:
Sit inside cold vehicle for a while (with car off) so that interior windows start to fog up - then turn on just the rear defrost, you can then see if it's on and operating.

Good luck.

 

[jasonstang]

Go to this link, once there scroll down to middle where it discusses how to test the defroster grid with a volt meter or test light:

https://www.frostfighter.com/defroster-repair-fix-it-guide.htm

Also, check the tab connections to the glass (if visible), found on the outer vertical grid lines. If one tab has detached from the grid or glass then the electrical circuit has been broken. The same is true if one of the harness connectors to the tab has become loose or fell off.


Another way to test:
Sit inside cold vehicle for a while (with car off) so that interior windows start to fog up - then turn on just the rear defrost, you can then see if it's on and operating.

Good luck.

Or he could spray some water and let it freeze and then turn it on.

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