More heat ad problems

Volvokoolaid · Post by **Volvokoolaid** » 07 Sep 2016, 14:56

Hi everyone,

I've recently purchased a 98 s70t5 and have noticed among other things that when I try to use the heat, nothing happens. The lights on the unit light up for the preferences I've selected but when I push the fan speed up nothing happens. Only a very very faint noise I can only hear if I place my ear next to the unit. I accessed the blower fan while turning on/off the fan speed switch I felt no vibrations and heard nothing coming from the fan. I've checked fuses and all are good. Is this a simple fan replacement? What's the next step?

Cheers

Post by **Ozark Lee** » 07 Sep 2016, 16:17

First double check the fuses again, there are two fuses for the climate unit.

It could be the blower fan or the power stage (blower resistor) that controls the fan. Power the fan directly from the battery to test the fan and it if doesn't run then that is the problem. You can power it directly by grounding the blue wire to something like a seat anchor bolt. If the fan runs and isn't noisy then chances are it is the power stage that is at fault. The power stage is expensive and if you want to be sure before you buy a replacement then about all you can do is get the unit scanned but it takes a Volvo specific scanner to do it.

...Lee

Volvokoolaid · Post by **Volvokoolaid** » 07 Sep 2016, 16:31

Thanks lee, I know this topic is played out.

I will check it out tomorrow. What is the power stage? Is it in the ecc? Or is it just to the left of the blower? Or is it the same thing as the blower resistor? I've heard people use both terms and I've gotten confused.

Post by **Ozark Lee** » 07 Sep 2016, 19:12

The power stage is inset into the main air duct, to the left of the blower as you look at the blower. The power stage is the functional equivalent of the blower resistor but in reality it is a MOSFET transistor for the ECC units. On the MCC it really is a resistor pack. The online parts stores usually call it a blower resistor for the ECC but Volvo officially calls it a power stage. Make sure that the part you buy, if that turns out to be the problem, is specifically called out as being for the ECC.

...Lee