HOW DO YOU TEST 850 HEATER BLOWER RESISTER PACK ?? ECC UNIT

TEAGLESON · Post by **TEAGLESON** » 08 Nov 2006, 07:26

mY HEATER BLOWER STOPPED WORKING IN MY 1993 VOLVO 850 glt SEDAN WITH eLECTRONIC CLIMATE CONTROL (ECC). This occurred when the heater core sprang a leak. I've installed the new heater core.
and now I need to fix the heater blower/fan.

I removed the fan and it works fine. The fan has power thru the red feed wire (serviced by fuse # 5). It runs on high speed when I jump the ground feed coming from the resister pack.

I removed the resister pack from the heater duct. and the 2 wire plugs.

Is there a way to test this resister pack to make sure this is the problem?

Is there also a fan relay in this car?

How do I know its not the ECC unit? This had to be repalced afew years ago when it went up in smoke (literally).

I've downloaded many error codes from the self diagnostic unit.

The car has 187K miles. I'm trying not to spend a lot of money.

Help.

Todd

email: [email protected]

Post by **billofdurham** » 08 Nov 2006, 11:52

The heater fan power is split into two parts. Fan speeds 1 - 3 are covered by fuse #31 which supplies power to the fan motor resistor unit. Fan speed 4 is covered by fuse #5 which supplies power to the only relay in the system, the max speed relay.

First check fuse #31 if you have not done so already.

I do not know of any easy way to test the resistor except by replacement with a known good unit.

What are the error codes you have pulled? It may help with a diagnosis.

Bill.

Post by **Ozark Lee** » 08 Nov 2006, 12:31

The ECC blower system uses a solid state system to control the fan in 12 speed steps rather than the 3 steps through the resistor that is used in the MCC units. There is really no reliable way to test it.

I did run across one on eBay.

http://cgi.ebay.com/ebaymotors/Volvo-85 ... dZViewItem

...Lee

TEAGLESON · Post by **TEAGLESON** » 09 Nov 2006, 11:21

Steve & Bill of Durham,

fuse # 31 is good as well as fuse # 5.

The AC unit is currently discharged. The evaportor went bad earllier this year.

I had the following codes before replacing the heater core & thermostat and before removing and testing the blower fan:

Note: Error codes shown with ** have been around since April 2005 when the ECC unit was replaced. The self adjustment mode 9-9-9 was used after replacing ECC unit.

1-3-5** (note: temp. guage on dash works)

2-1-1

2-3-5**

3-2-1**

3-2-5 ** (note: recirculation damper opens and closes using ECC switch)

4-1-1 ** (note: blower fan works fine - high speed using jumper wire to provide a GRD)

4-1-4

4-1-8

4-1-9

I used the haynes manual to find the diagnostic codes. I have not checked the components associated with each error code except as noted.

After replacing the heater core & thermostat and testing the blower unit, i read all of the above codes and reset the diagnostic unit.

I have driven the car, the fan does not work. I now only have 2 codes in the diagnostic unit: 2-3-5 & 4-1-8 which I previously had.

I also read the A/C heater section of the 1995 manula posted on online. Many of the component tests require you to hook up a VOLVO test unit and check voltage/restistance/etc. across test unit pins and components.

I do have access to another 850 to borrow componets from in order to isolate the faulty compenents.

Any thoughts?

Todd

I will post this same reply on the other posting as well.

Post by **billofdurham** » 09 Nov 2006, 15:33

Code 1-3-5 would not affect the temp gauge as there are two sensors, one for the ECC and one for the gauge.

Codes 4-1-8 & 4-1-9 are indicating faults in the resistor. If you can try the resistor pack from the other car it may show that this is the trouble.

I feel that some of the other codes will sort themselves out if you can get the power back to the fan. It is amazing how one fault can snowball in complicated systems like these. Thankfully, I have a manual climate control.

Bill.

TEAGLESON · Post by **TEAGLESON** » 09 Nov 2006, 15:45

I made a typo. I do Not have access to another 850 to borrow parts from.

Thanks for your input

Todd

steve · Post by **steve** » 09 Nov 2006, 19:32

I would first erase all codes, confirm that they are erased, then see which codes reset.

I would then bite the bullet and replace the resistor pack if the blower still did not work. I would also suggest replacing the blower while you were at it. True, the blower may work,now, when you hook it direct to 12 volts, but I would personally not take the chance of having an older blower, that possibly is nearing the end of its life, fry itself and take out a new resistor pack, that I spent good money on, with it.

If the blower previously made any whirring/clicking noise, I would feel all the more strongly about replacing it. You will have to rely on your own judgment here.......

If code 235 were to reset itself, 235 is Recir. Damper motor position sensor open or shorted to power. Relying heavily on the 1995 downloadable manual section regarding the ECC I would first check the connection at the connector to the damper motor. If that checks out ok I would check the internal resistance of the damper position sensor using paragraphs 8 & 9 of the DTC 235 diagnostic section in combination with Figure 11 as shown there. You'll need a DVOM and know how to use it to test for Ohms (resistance).

It is difficult to check the wiring from the ECC to the damper motor without the pin-out box from Volvo.

I cannot be of any great help with code 418, but I agree with Bill in that it may go away with getting the power back to the blower, and I feel replacing the resistor pack is the key.

Code 414 is the temp probe / intake fan seizure. This one will come and go until the thing is either cleaned or replaced. You can check out the other thread I wrote regarding this one.

Post back and let us know which codes reset.

S

bobsnow100 · Post by **bobsnow100** » 10 Nov 2006, 07:44

I believe there are two relays that also are for the heater blower fan, They are left (about 6 Inches) next to the resistor pack where it is mounted. This believe this could cause this problem

TEAGLESON · Post by **TEAGLESON** » 22 Nov 2006, 14:47

UPDATE

Just installed the new blower resistor pack. The fan works great. Have variable speed and full speed.

I cleared all the codes and then drve the car.

I checked error codes again and have 2:

2-3-5

& 4-1-8

The Auto AUTO setting does not work but I am happy.

I now have heat again and can control the temperature and fan speed.

Todd