Invective

Didn't find a thread concerning this subject in the S197 category so I'll start one.

My defroster failed to clear the rear window recently even though the switch illuminated (didn't hear the relay click). There is no fuse as far as I can tell and just the one relay under the hood. The connection at the rear window is good but the relay connections needed cleaning and now it seems to be working (can hear the relay). Anyone else have issues with this? Car currently has 21k miles.

Invective

RW defroster stopped working for this season.

1. Light on switch comes on then goes off by itself like it always has but but no defrosting action is taking place.

2. At the beginning of the next driving cycle when the key is first turned on (but car not started) a clicking sound can be heard coming from behind the dash briefly then stops, car starts normally. Only happens when I attempted to use the defroster during the previous driving cycle - not at any other time.

Owners Manual doesn't show a fuse but it does show a plugin relay at the #29 position inside the underhood fuse/relay box. The connections at the rear glass look good with no broken wires, etc.

Unplugged the relay, cleaned the 4 blade connectors - no difference. The clicking noise seems to be coming from behind the dash but I'm wondering if its actually coming from under the hood?

Will run this scenario through multiple Mustang forums attempting to get the best possible sample of responses. Thanks in advance.

Goldenpony

Have you tried disconnecting the two wires to the defroster and checking to see if there is voltage when the button is pushed?

Dimwit37

Fuse 52 under hood should show it in owners manual then replace relay with another one and see if it works

Invective

You are correct about the fuse in the #52 position. Light on switch button comes on, indicating a good fuse. Spoke to the local dealer who stated it was the relay, as long as the heating grid and connectors were good. Dealer parts dept. couldn't give me a price on the relay - they want me to bring it in. Internet pricing is between $19 - $26 for a new unit; $3 - $8 for a used unit. Won't even consider a used unit unless it was locally purchased with a return guarantee.

Thanks for the info.

Dimwit37

If it's the relay it's right by the fuse pull it out and switch it with a similar one see if it works I wouldn't bring it in for that that is as easy as changing a fuse boss if the new relay works when u switch it get one from auto zone they have them

Invective

Good advice and this did clear up the issue. Several identical relays - switched two around (the other regulating the blower) and the defroster started working and the blower continued to work. Dealer even recommended this before spending money.