Hi all,

I am new to the Volvo cars and my first impressions are very good. I have picked up a 1994 850 and looking to fix a number of problems.

The system has the 2 flashing AC lights that indicate the system has a problem and the fan is not working.

I did a DTC and it came back with the following

2-2-1 ................. Pass. Side Damper Motor Position Sensor Circuit Open Or Shorted To Power
3-2-5 .............. Recirculation Damper Motor Active Too Long
4-1-1 ......... Pass. Compartment Fan Overcurrent Or Seized Fan
4-1-4 ............ Driver’s Side Temp. Sensor Intake Fan Seized
4-1-8 .................... No Control Signal To ECC Power Stage
4-1-9 ....... ECC Power Stage Emitting Faulty Diagnostic Signal

I pulled out the fan motor and it was a bit stiff but when I connected it to power worked okay

When I did the following : 4-1-9 2) Turn ignition on. Connect voltmeter between test unit pins No. 6 and 27. Voltmeter should indicate 3 volts. If voltmeter indicates one volt, there is no control signal to power stage. See DTC 4-1-8, NO CONTROL SIGNAL TO ECC POWER STAGE. If voltmeter indicates 4 volts, there is excessive voltage from power stage. See DTC 4-1-1, PASSENGER COMPARTMENT FAN OVERCURRENT OR SEIZED FAN.

I did get 4v so This points back to the fan, however as indicated above when I connected 12v to it, it turned around okay.

I gather that the 4-1-1 is the main blower fan?

Given the above codes can some one point me into the right direction?

 

I would clean the connections, reset the codes and try to run the system again if you haven't done that already. Then pull codes and see what returns.

The thing about these systems is the domino effect in the codes. One problem will trigger one code after another. I almost ran out of gas once and popped about 8 codes.

 

I cleaned the fan connectors if that is the ones your referring to. I did not have much luck resetting the codes, ie held down the A button for 5 sec and the 5 more but still the same codes came back.

I the main question I was asking was given the list of codes can you recommend a place to concentrate on.

Thanks for your advise

Troy.

 

The 418 sticks out because that would indicate no power. IMO

I would check out the blower motor resistor as it may have failed and that's why you have no blower. The best thing to do is to take a test light and find out if you have power going to the blower motor.

 

Just checked the volts at the blower plug - 7v so that is less then it should be?

I unplugged the resistor pack and re tested the plug and it had zero volts. Any suggestions on how to test the resistor pack?

I plugged in a new fan motor however as it only has 7v's I guess that is why it will not turn

Thanks again for your input.

 

Download this file

2shared - download Volvo_850.zip

and then open the "1995" folders until you get to the page of PDF files. Open the one for "AC heater system auto" and go down to the instructions for trouble code 418. That voltage could be the correct voltage if you're checking the correct pins.

 

The suggested file is where I have obtained all the information so far, so good to know I am on the right track.

2) Turn ignition on. Place fan control lever to maximum speed. Connect voltmeter between test unit pins No. 6 and 42. If 6-8 volts are present, go to next step. If voltmeter indicates zero volts, wiring is shorted to ground. If voltmeter indicates 12 volts, wiring is shorted to voltage. Repair wiring as necessary.

At this point the volts are .45 so close to being shorted, this has directed me to the resistor pack, which I have dismantaled and found it is K1423 (N-Channel MossFet). Being a big Moss (around 80amp switch) I am unable to locate one. My next step is work out how to test this item. I am thinking I can bridge the D (drain) and S (Source) pins, which should give me power to the fan?

 

Just to let you know I found this

AWD - How to remanufacture your Blower powerstage yourself- final update

Will let you know how I go once I have replaced the transistor.

 

If you go to the link above it talks about the shape of the transistor. If anyone knows where to get a compatable TO-3p transistor, please post it. I tried radio shack, digikey and a couple others without luck.



Hello Mark,

Thank you for contacting Technical Support.(digikey)

Unfortunately I'm unable to find a N-Channel Mosfet that would be compatible in a TO-3P package.

Thanks again and let me know if I can be of further assistance.

 

I ended up using - MTP75N05HD and extending the legs, however this did not fix my problem. Seems that the Main ECC is not sending the controller 6v to start (violet and white wire) So I am now looking around for a second hand ECC and hope that is the problem. Not easy to come by as most of the cars have the standard system. I have pulled the ECC apart but could not find any noticeable issue.

Has any one got a circuit layout of the indside of the ECC? I could then test the driver transistors to see if one has popped or the IC for correct triger volts?

 

I have checked all volts at the connectors and it looks like the control wire to the resistor pack is only .4v this should be 12v. I have traced the circuit and found that the 12v stops at a 47k resistor, so next I have to work out if it is faulty or if it is the IC.

 

After putting the power module on to a scope it is not sending back the good signal so I have ordered a new one. Can any one tell me if the LHD is the same as the RHD? The numbers are different my one is rhd 9144355 the lhd one is 9144354.

 

For any one interested, the LHD module is not a straight forward swap in. The reason I went for the LHD module was the one in Australia was $300 and the imported one from the US including postage was $150. I had to grid away some plastic mounts and create a new mounting point at the bottom. However as it works and I get cold air, we are happy.