Heater blower quit Topic is solved

swe280Z · Post by **swe280Z** » 11 Feb 2017, 11:07

1994 850 manual heater fan quit. Fuses good, replaced motor and resistor, motor first. Switch activates vents, etc but no blower. Is there a relay I'm missing and where? Next step? Thanks.

Post by **abscate** » 11 Feb 2017, 15:52

Go to the blower and look for 12 volts. You troubleshoot electrical stuff working backwards, starting at the failed component.

Post by **rspi** » 11 Feb 2017, 18:57

Could also be the switch.

Post by **rspi** » 11 Feb 2017, 18:57

You can also put 12 v on the old motor to see if it works. They almost never just flat out fail.

Post by **Ozark Lee** » 11 Feb 2017, 22:59

The A/C - REC switch is a weak link. You can usually verify that the problem is there by reaching up behind the panel through the radio position and squeezing it.

...Lee

swe280Z · Post by **swe280Z** » 18 Feb 2017, 14:54

Do not have 12 volts at the new blower. Old blower works when 12 volts applied on bench. No voltage to blower when AC/recirc squeezed. What is the best way to check the fan switch even though vents, A/C makes noise when fan switch moved to different speeds or A/C button and recirc button pushed? Could I have fried a wire? Are there any fusible links? I noticed a couple pieces of black over-heated electrical tape on the main wire bundle coming over from the left(might just be old) Thanks for any suggestions.

Post by **Ozark Lee** » 18 Feb 2017, 15:13

The way the manual system works is that speeds 1 to 3 go through the blower resistor and speed 4 gets routed directly through the max fan relay.

First off look for voltage on the Green/Red wire that goes to the blower on all speeds. There is a failure mode on the max fan relay where nothing can get through it but it is not they typical failure mode. If you have no voltage on the Green/Red wire go to the max fan relay and look for voltage on the Red wire and the Green wire. If the max fan fuse is good you should definitely have voltage on the Red wire and, with the key in position II, you should have voltage on the White wire with the speed selector in position 4.

If you have no voltages there then you need to go back to the speed selector switch and look for voltage on Yellow/Violet wire which if the fuse is good should be there with the key in position II.

There should be voltage on the following wires with the key in position II:

Fan Speed 1 - Blue wire.
Fan Speed 2 - Blue/White wire.
Fan Speed 3 - Brown wire.
Fan Speed 4 - White wire.

If you have voltage on the Yellow/Violet wire but none of the other wires above it is a bad fan speed switch.

...Lee

swe280Z · Post by **swe280Z** » 20 Feb 2017, 10:33

No power to red/green wire to blower at any speed with key on position II. Fan relay has power on red and white wires but none on green. Speed selector switch has voltage on blue, blue/white, brown and white wires on respective speed settings as well as yellow/violet at switch. Any ideas?
Thank you. At least the new fan blows harder than the old one when I jumper it! I gave it white lithium grease before I installed it.

Post by **Ozark Lee** » 20 Feb 2017, 17:41

That tells me you have two problems. The first is the bower resistor since you have voltage coming into it but nothing coming out. The blower resistor has a thermal fuse and I have heard of people soldering in a new thermal fuse like one that would go into the burner on a coffee pot but you really need to use silver solder to do it and it is tricky to get the solder hot enough to flow without taking out the new fuse in the process. On the original it is spot welded in. The second problem appears to be the max fan relay since you have voltage going into it but nothing coming out.

The relay is relatively cheap and super easy to change. The blower resistor is easy to change but not cheap. Many of the online parts stores refer to both the MCC and ECC fan speed controllers as blower resistors but they are very different and not interchangeable. If you buy a new blower resistor be sure to get the correct one. The correct blower resistor for the MCC is the cheaper version of the two parts in almost all cases.

...Lee

swe280Z · Post by **swe280Z** » 20 Feb 2017, 21:54

In the past month I have purchased 2 Professional Parts-Sweden blower resistors #9137937 without success. Could the relay alone cause these voltage readings? If this is possible, I'll be spending about $35 (including shipping) for #9494787 Volvo green relay from the same supplier in CT. I don't mind having already replaced the fan motor as well considering the car spent the first 22 years without a cabin filter. I appreciate the help from those of you with much more Volvo history than I. Thanks again.
...Scott