850 intermittent heater / blower function ...

[wyoben]

So Howdy everyone … I have a 94 850 turbo W/ECC, here's the short/short version of problem first off I pulled codes and I know I have a few issues W/ actuators etc , codes I got were 231,233,511 …not too bad since when I got the car it had no dash …It seemed to be blowing hot air and would function enuff to get by , but now what happens is …When I Start car, blower runs full speed or wherever I place speed switch …after about 5? min blower quits , no screetching no noise ,just quits… If I shut car off fire it up and it does same thing , everytime I restart motor blows great then quits …Anybody got any tips ? thanxz in advance !
Update ...It appears that when I ran the blower on manual with the engine NOT running and key in position II the blower did not kick off ?

[scot850]

The symptoms sound like either the ECC unit is faulty (they go flaky at this age), but normally the fact that the fan runs flat out is because what is called the 'resistor pack' has failed.

Is the ECC set to defrost by any chance?

Neil.

[wyoben]

Scot850 ,thanxz for the quick reply,I don't think I'm getting notifications,I just saw this...Anyway ...Yes it was,but I moved it to other positions . I don't understand why when I shut the car down and restart , it blows like new,no noise nothing ...then the other tentative observation is when I place key in pos. II engine NOT running ,it seems like it doesnt kick off...but why did you ask if it was on defrost ? thanxz Again for the help 1

[scot850]

Well on defrost, the fan normally goes to high setting automatically on ECC units. If you move it off defrost and get same issue then it is not that which is causing the full on fan action.

Switching off the ignition and then back on resets the systems. Then when they start running again they heat up and if it is a short will fail again.

If you have noise or variable speed when the car is running, it is often signs the motor bearings are dry or failing. Can't recall which way it goes, but when accelerating the fan is pushed toward the back of the car and can bind when the bearings are worn, and when you brake the fan moves off the back of the bearing and speeds up.

If you have a one speed fan most of the time then it is the resistor 'pack' that is bad. The default is full speed.

Neil.

[jreed]

From the description of the fan running at full speed, I agree it sounds like the power stage / fan speed controller may have failed. One of the failure modes of the power transistor is to fail "closed" which causes the fan to run at high speed.
On the blower motor, my experience was that the bearings would squeal when the car was turning left or right.

[scot850]

Mine was the fan ran faster or slower depending on accelerating or slowing down when the bearings were worn, no particular noise from the bearings, but I had lubed them.

Neil.