Smoke from glove box. now AC fan wont work '93 850

nickdude814 · Post by **nickdude814** » 09 Aug 2011, 17:24

I was driving and all of a sudden smoke started coming out of my glove box
i could smell something burning and now the fan for the AC wont work
there hasnt been any more smoke
im sitting in my garage with the glove box out and the underside plate off looking at wires and a fan housing
what could this be and what should i check?
Thanks!

Post by **Ozark Lee** » 09 Aug 2011, 17:36

Welcome to MVS,

Before we can go much further we need to figure out if you have the manual climate unit or the electronic climate unit. The electronic unit has several positions marked Auto and the temp settings are graduated in actual degrees. The manual unit has fan speeds from 0 to 4 and the temp settings are marked with graduated width red bars.

Once we know what you have we can try to point you in the right direction.

...Lee

nickdude814 · Post by **nickdude814** » 09 Aug 2011, 17:50

i have electronic

Post by **Ozark Lee** » 09 Aug 2011, 18:36

Yank the radio, you don't need to actually unhook the wires to it but if you do you will need the radio code.

After the radio is out press the climate unit from behind and it will pop out of the dash.

Once it is out and you remove its connectors remove the cover plate and look for burned up stuff on the circuit board and a big scorch mark on the top of the cover.

It is a common problem with a result that only replacing the ECC unit fixes. I am still trying to get my hands on a blown up unit so that I can figure out a component level fix. From the pictures I have seen there is always an electrolytic capacitor that has blown up and I think I was installed with reverse polarity from the factory but until I can get my hands on a bad one I can't tell.

...Lee

pgbuick · Post by **pgbuick** » 10 Aug 2011, 09:21

I am the other, older guy working this issue with my son. There are no apparent burn or scorch marks on the ECC unit. The blower motor is not siezed. I would like to power it up outside the car but don't know which terminals to put power to. We haven't pulled codes but will do that tonight. Since the smoke came from the glovebox area and not out of the vents, does that point to something other than the ECC unit, for example, the resistor/heatsink assembly? Are there any diagnostics we can do on the resistor assy, such as checking resistance or powering it up outside the car? Thanks!

Post by **Ozark Lee** » 10 Aug 2011, 19:40

pgbuick wrote:I am the other, older guy working this issue with my son. There are no apparent burn or scorch marks on the ECC unit. The blower motor is not siezed. I would like to power it up outside the car but don't know which terminals to put power to. We haven't pulled codes but will do that tonight. Since the smoke came from the glovebox area and not out of the vents, does that point to something other than the ECC unit, for example, the resistor/heatsink assembly? Are there any diagnostics we can do on the resistor assy, such as checking resistance or powering it up outside the car? Thanks!

You can hook up power in either direction for testing purposes. It will run forward with one polarity and backwards with the other but it is just a DC motor and it really doesn't care. For testing purposes I normally just remove the connector with the larger blue and the black wires from the power stage (blower resistor) and short them together with a jumper wire. The fan should run full blast in that condition. At that point it usually pinpoints the problem to the power stage it self but not always.

The power stage is inset into the main air duct just below the glove box. The stuff that leaks out the smoke is actually pretty much above the duct. It confirms the Arkansas Smoke Theory - everything runs on smoke and when the smoke leaks out it doesn't work anymore.

Read the codes from port B-1 and post them back. If you have a bunch of them read them all and then clear them and see what comes back. The ECC is like an elephant - it never forgets anything that has ever been wrong.

...Lee