ECC Power Stage/Resistor Help

[Peters911s]

1988 760 B230FT with ECC....A/C light flashes on whenever I try to use the blower...Code I pulled is 233 (Too much starting current for blower etc)...Pulled the blower...Was original so replaced it with new. Verified it works, but would still only move less than an inch before the A/C light flashed back on.
Pulled the Power Stage/Resistor and Replaced the transistor inside...Still not turning the blower.

Any other Ideas? ECC unit itself or bad Power stage?
Anyone have either available?
Thanks in advance for any help,
Peter

[lummert]

I had the exact same problem with my 1988 760 Turbo Wagon. Last winter I unplugged the power stage/resistor and ran 12 volts from the 12 volt ignition switched tap on the relay panel though a heavy duty switch and a .7 ohm ballast resistor to the blower motor. I figured having the blower running at half speed was safer than no fan at all. I haven't done anything else with it.

[Peters911s]

Appreciate the feedback....I realize we often need to be "Macguyvers" with these cars...but was looking for something more permanent...Anyway to test the ECC control panel itself?...or shall I try and find a used Power stage first?....Anyone have the above resistor used that they want to sell me?

[93Regina]

...Anyone have the above resistor used that they want to sell me?

How to fix a 740 940 heater motor resistor

Also: PWM blower

[lummert]

...Anyone have the above resistor used that they want to sell me?

How to fix a 740 940 heater motor resistor

Also: PWM blower

The blower motor resistor on 88-90 760, 91-92 940 SE, and 960 cars is not the same as on a 740/940. The a/c heater system on these cars is supplied by Harrison France. (GM). The blower motor is GM. I'm running a Pontiac Sunfire Blower motor on my 760.

[Peters911s]

I replaced mine with part number GM # 52474449 new for $35 inc Shipping....can't seem to find a power stage for less than $150 though...Anyone know of a Bypass for the power stage?...even if it only runs on high I'm fine with that as long as i can get it to run at all....

[lummert]

I replaced mine with part number GM # 52474449 new for $35 inc Shipping....can't seem to find a power stage for less than $150 though...Anyone know of a Bypass for the power stage?...even if it only runs on high I'm fine with that as long as i can get it to run at all....

I used the GM blower motor connector plug and ran the ground wire to chassis ground. I ran 12 volts from the switched 12 volt rail on the relay panel. I wired the 12 volt through a heavy duty school bus rocker switch and a .7 ohm ignition ballast resistor (commonly used on older Chrysler vehicles) to the blower motor. The ballast resistor lowers the voltage to 9 volts lowering the blower speed. The blower speed on 14 volts is really fast. The original blower motor positive wire contained a solid copper wire wound resistor.

[93Regina]

The blower motor resistor on 88-90 760, 91-92 940 SE, and 960 cars is not the same as on a 740/940.

That PWM cite should get a blower motor working OK.

Maybe not related: 1994 Auto. A/C-Heater System Volvo 960

Volvo 960 climate control & heater system repair manual

[swiftarrow]

Hi! I have the exact same issue with my 1988 760.

Code 233 with the electronic climate control.

I too changed the blower motor which did not fix the issue.

So here’s what I’ve learned so far: Volvo has a few different varieties of climate control, but broadly they fall into two categories: ACC (Which uses vacuum circuits and a resistor to control louvres and the blower motor) and ECC (the smart system which senses temperature and adjusts accordingly).

Telling them apart: ECC has an “auto” function and you choose a temperature rather than a selection between hot and cold. ECC is found in the luxury editions of our beloved bricks: the 760, 940 SE, and 960.

Compatibility: head units (the piece with the dials and buttons) are comparable at least from 88-95. I swapped my 88 760 head for a 95 960 head unit and it works just the same.

The blower motor: many people have had issues with the blower motor not working, but it’s not always the blower motor. Error code 233: blower motor starting current too high. This is analogous to the resistor, except it allows the computer to control the fan instead of a switch. It’s basically a fan power stage. It costs a LOT of money if you can find it.

I am going to look into repairing mine. A friend sold me one from a junket and it works in mine, but seems to have a differentt plastic housing, so I’ll have to fix mine. I will update here if I get to it.

Questions: do other cars have fan power stages that could potentially be swapped in? Even if it’s not a perfect fit...

[enferm82]

Hello,

I have a problem with my 780 blower fan motor, I am after the resistor part number 3506972. Any help is greatly appreciated