# 95 Sentra Rear Defrost Problem



## Scozie (Sep 11, 2010)

I am having an issue w/ my rear defrost and cannot figure out what's wrong. When I activate the defroster, it comes on for a few seconds, then turns off. I have tested the switch and it appears to be OK. Is there a relay? Could it be a broken element? 

Any help is appreciated! Thanks!


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## smj999smj (Jan 1, 2006)

WOuldn't be a broken element. Could be a faulty relay or a bad timer. If you have power door locks, the timer is built into the smart entrance control unit. If you have manual door locks, then you have a rear window defogger control unit. Here's a description of the system:

Description and Operation 


If equipped with power door locks the rear defogger system is controlled by the smart entrance control unit. If not equipped with power door locks the rear defogger system is controlled by the rear window defogger timer. The rear window defogger operates for approximately 15 minutes.
Power is supplied at all times:


through 2O A fuse (No. (4) ,located in the fuse block [HEC]) 
to rear window defogger relay terminal (3) and 
through 2O A fuse (No. (5) located in the fuse block [HEC]) 
to rear window defogger relay terminal (6).
With the ignition switch in the ON or START position, power is supplied:


through 7.5 A fuse (No. (7) located in the fuse block [HEC]) 
to rear window defogger relay terminal (1) and 
to smart entrance control unit terminal (11) (models with power door lock), or 
to rear window defogger timer terminal (1) (models without power door lock).
Ground is supplied to terminal (2) of the rear window defogger switch through body grounds (M43), (M44) and (M60).
When the rear window defogger switch is activated, ground is supplied:


through terminal (1) of the rear window defogger switch 
to smart entrance control unit terminal (20) (models with power door lock) or 
to rear window defogger timer terminal (3) (models without power door lock).
Terminal (36) of the smart entrance control unit (models with power door lock) or terminal (2) of the rear window defogger timer (models without power door lock) then supplies ground to the rear window defogger relay terminal (2).
With power and ground supplied, the rear window defogger relay is energized.
Power is supplied:


through terminals (5) and (7) of the rear window defogger relay 
to rear window defogger terminal (1).
The rear window defogger has an independent ground.
With power and ground supplied, the rear window defogger filaments heat and defog the rear window. When the system is activated, the rear window defogger indicator illuminates in the rear window defogger switch.
Power is supplied:


to terminal (3) of the rear window defogger switch 
from terminal (7) of the rear window defogger relay.
Terminal (4) of the rear window defogger switch is grounded through body grounds (M43), (M44) and (M60).


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## Scozie (Sep 11, 2010)

Thank you! I purchased a Haynes manual and have scoured google, but I can't find where the rear window defogger timer is located (or the relay). ((I have manual locks.)) 

Do you happen to know where they are located? 

Thank you!!!


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## smj999smj (Jan 1, 2006)

Rear defogger relay is P/N 25230-7996A, lists for $27.60, and is located just under the fuse block, behind the left side of the dashboard.

Rear defogger timer is under the dashboard, driver's side, to the right of the steering column.


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## Scozie (Sep 11, 2010)

smj999smj said:


> Rear defogger relay is P/N 25230-7996A, lists for $27.60, and is located just under the fuse block, behind the left side of the dashboard.
> 
> Rear defogger timer is under the dashboard, driver's side, to the right of the steering column.


Thank you very much!!!!


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