1998 S90 blower replace when replacing blower resistor?

[93Regina]

power being sent to the fan directly

Without seeing MCC/ECC dash units, I know nothing, but schematics suggest otherwise.

I can't lookup your specific part, but for one ECC, it cost around $500.00 new, so jerry-riggers do what-ever it takes.

If you scroll down that page to Fitment/Applications, and open it up, you can see what vehicles this ECC went on. Interesting, I'm not seeing the MCC control unit in Volvo's parts (VADIS)

If you see one of these on your Volvo, then yours is an ECC system

[lummert]

I tried suggesting installing a 1.1 ohm ignition ballast resistor in the battery positive wire to the blower motor. It will slow the blower speed down to about half speed. Then put a switch in the ground wire to turn off the blower motor when not needed.

[jefflamonica]

Okay, I got around to testing more things on the HVAC system. I pulled the #7 fuse and no blower. Put it back in, and it ran at full. (I say "full" but I have not tested to see if I have full battery voltage at the blower.) Not sure of the next step, but tempted to use the 20 amp PWM fan controller. Just have to figure out the correct place to mount it for RF interference and heat. If worse came to worst, I could live with the blower on all the time. I'd just adjust air direction and temp for comfort.

On the AC compressor, I pulled the connector at the low-pressure switch and jumpered it. The compressor did not kick on. The engine RPMs did rise a bit, just like when I turn the AC switch on on the control unit inside the car. Checked the #2 AC compressor fuse in the engine compartment. It was good. Tested for voltage at that fuse location. Showed 13.6 volts. I guess testing the AC relay is next. I noticed, in the relay box in the engine compartment, several of them have a big "J" printed on them. Are they all the same? Could I swap one for the AC relay and see it it works? Otherwise, what is the procedure for testing the relay? And what is the next step after that?

[93Regina]

And what is the next step after that?

Wing it...see wiring diagram for your vehicle.

Lummert has made a cheap suggestion...using a resistor and a ground switch...

Bosch relays of this type have been standardized, where 30 is your feed power, and terminals 87 and 87a are the output power points.

I will hook direct to A/C compressor, to see if it moves...if so, then you trace backwards the circuit.

Relay Basics

[jefflamonica]

power being sent to the fan directly

Without seeing MCC/ECC dash units, I know nothing, but schematics suggest otherwise.

I can't lookup your specific part, but for one ECC, it cost around $500.00 new, so jerry-riggers do what-ever it takes.

If you scroll down that page to Fitment/Applications, and open it up, you can see what vehicles this ECC went on. Interesting, I'm not seeing the MCC control unit in Volvo's parts (VADIS)

If you see one of these on your Volvo, then yours is an ECC system

Hey, 93Reg. I looked at the part you linked to. Looking at the 1997- version, I'm looking at $625. Haha. I don't think so. But, oddly, that looks exactly like my control unit, and is labeled ECC. I thought the ECC units all had the slider control for the fan. Obviously, the wiring diagrams, and this, are telling me mine is an ECC system. I needed a fan speed knob, and found a control unit on eBay for $25. They guy got it with a bunch of parts from a Volvo mechanic, so couldn't confirm it was in fully working order. Tried to pull a knob off of it yesterday, and couldn't do it without breaking something. Is there a trick to that? Maybe I'll install this newly-acquired unit and see what happens. Any DIYs out there for removing the unit from the dash?

Regarding the Air Flap Actuator Solenoid, I haven't dug that deeply into the dash to see that.

[lummert]

Removing the trim located at the right side of the steering column should give you access. There are several switches in that trim panel. You may need to remove the switches before removing the panel.

[93Regina]

Tried to pull a knob off of it yesterday, and couldn't do it without breaking something. Is there a trick to that?

With MCC units, you might be able to pull off knobs, but not on ECC units.

Is there a trick...yes there is...Youtube is your friend...at your own risk below..