Ecc flashing lights-blower not working.

roryb · Post by **roryb** » 09 May 2012, 21:03

I am getting the flashing lights as seems to be a common problem. The blower does not work and the lights flash for approx 20 seconds.
I removed to blower motor and it works when connected to the battery so i presume that's not the issue.
The blower does not work on full speed and the resister looks fine upon removal so I presume it is not that also.

What else could be the problem? the Ecc has power as the lights are flashing.
The blower does not spin at all. There is a slight delay and possibly a slight click sound before the lights start to flash.
Any ideas?

Post by **Ozark Lee** » 10 May 2012, 08:07

A visual inspection of the blower resistor (power stage) really won't tell you anything. The guts of the power stage is a MOSFET transistor that can fail with absolutely no visual evidence.

Since the blower works when hooked up to a battery chances are that the power stage (blower resistor) is bad but the only way to know for sure is to have a dealer or an indy that has a Volvo scan tool or its equivalent check the codes.

...Lee

roryb · Post by **roryb** » 10 May 2012, 16:46

I was of the opinion that if the blower didn't work at full speed then it was not the resister at fault?
Am I wrong and it could still be the resister even if the blower does not work at full speed?

Post by **BEJinFbk** » 10 May 2012, 17:33

Bear in mind that the 850's and V70's shipped with two systems.
The Manual Climate Control (MCC) is a pretty basic setup.
The Electronic Climate Control is automated and "smarter".

I think you may be confusing the MCC ( that uses actual resistors
for the lower blower motor speeds ) and the ECC that your R has.
ECC uses the mosfet based electronic power stage for the blower.

A lot of confusion results from people calling the power stage a resistor. It's not.
It's more of an ECC controlled variable output power supply for the blower motor.

One of the big differences is that the 4 speed MCC has a full speed override relay
that totally bypasses the low (1,2 & 3) speed resistors for the highest speed, #4.
If MCC runs at speed 4, but not the lower speeds, it's often a bad resistor pack.
With the ECC, the power stage is variable and provides power to the blower motor
at all speeds. If the mosfet dies, it'll usually short and be full on, or open at full off.

Something else that may be shutting you down is a dirty cabin air temp sensor.
It's worth taking a minute and giving it a shot of canned air. That may work.
I've had to do that twice in 7 years to clear the blinkies...

: tempsensor.jpg (4.5 KiB) Viewed 2522 times

If you need real answers, the ECC has a diagnostic system, but you'll
need a propietary Volvo tool plugged into the OBD ll port to read them.

Post by **JRL** » 10 May 2012, 22:22

Cabin sensor not there in 850s

Post by **BEJinFbk** » 11 May 2012, 00:00

OP is driving a '98 R.

Post by **JRL** » 11 May 2012, 06:29

My mistake, replace the sensor first

roryb · Post by **roryb** » 15 May 2012, 10:49

Thanks, I will remove the cabin sensor and clean it this evening.
Is there a small fan in the sensor that clogs with dust and dirt that can cause this issue also?

Post by **BEJinFbk** » 15 May 2012, 11:20

Before going to the trouble of removing it,
just shoot some compressed air through it.
If it's just gunk on the sensor, you're done.

If the tiny fan has failed, you'll still get lights.
These both assume that the sensor really is
the source of your fault indication.

roryb · Post by **roryb** » 16 May 2012, 00:34

So I removed and cleaned the cabin sensor and fan. I tested it as I reinstalled it and the fan works fine.
Is there any way of checking that the ECC 'resistor' is working? Can I check voltage before and after the resistor?
Or is it a case that if the blower, ECC controls and sensor are working, then its the resistor at fault?
Thanks again.