daturbosix

iTrader: (3)

it just quit working on my 2001 formula.

30a breaker is good. from what i see, it shares the power seat breaker. seats work fine.

i have power at the wires to the button on the control panel. when i press the button, it doesnt light up and the rear defrost does not work.

what else should i be looking at?
yes my defrost grid is fine. i think the board in the control panel is fine, as the switch does operate, and i hear the mini relay click when i depress it, but the indicator light still doesnt come on. unfortunatly i dont have another defrost board to try at this time..

dont know if there is any relation, but the indicator light for my traction control button also stopped working at the same time. however, the traction control still turns on and off and operates as normal.

wssix99

iTrader: (5)

I'd still test the breaker by replacing it with a 30A fuse just for a test or switching the two breakers. (BTW - I do not advocate using a fuse long term here.) The breaker could be borderline and quickly resetting.

If the problem still happens, you'd have to trace the electrical going in and out of the board.

daturbosix

iTrader: (3)

no change swapping the breakers. and same thing with a fuse.

Phil424

Most likely the control unit which is built into the HVAC control head unit is bad. Its a 100 dollar part.

daturbosix

iTrader: (3)

do you know if the control board is able to be bought separate from the whole hvac panel?

ok got it working! apparently that circuit board was bad in my hvac control panel, i simply swapped it out with another one and now it is all good.

after i swapped the control board the defrost started working again, but it would shut it self off after a short amount of time. i noticed that my power seats also stopped working temporarily, so i picked up a new circuit breaker from napa for $6 and so far so good!!

Phil424

Yeah that is a very common problem. Don't be surprised if it stills shuts off after a short period of time with the new circuit breaker. I had the same problem along with many others. The fix for this is to use a 30A regular fuse in place of the breaker and the problem will never come back.

wssix99

iTrader: (5)

If you still have the old breaker, its interesting to take it apart and look at the charred insides. Between the defogger and the power seats, the breaker really takes a pounding.


This is not a true statement. If a new breaker is good and it still shuts off, there is probably a control board problem, like the OP encountered here.


This is not a fix or sound advice. There is a reason why GM installed a (more expensive part) breaker instead of a fuse. The technical merits are discussed in other posts.