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I am trying to track down a snag in the heater fan on this 1992 Volvo 964 with air conditioning.
The fan does not come on at all, no matter what combination of heater/blower/temperature selectors I choose.
I have two pictures of the blower motor, taken after the glove box and dashboard undercover have been removed.
Can anybody tell me which of the outlined parts is the resistor?
And is there any giggling, etc., that can be done to try and resurrect it?
As per usual the technology defeats me. I cannot get the image I want uploaded. I do have a couple of images where I indicated which item might be the resistor but I cannot get them to upload.
Bob
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Dear muskox37,
Hope you're well. The heater resister is mounted in the top (upper) surface of the air duct, to the left of the blower motor enclosure, as you face the windshield.
The resistor is secured with two screws which - if I recall correctly - are T-20.
Most of the resistor is inside the air duct.
I do not think that "giggling", chuckling or even a full-scale laugh will help to revive a failed heater resistor!
Most likely the termal fuze - a small, tubular device mounted on "bare metal wires" that come out of the resistor pack - has burned-out. Were Radio Shack still in business, a replacement fuze could have been found there.
A recent post - within the past three months - had the specifications for this fuse. I had intended to note this thermal fuse's specifications.
This part likely can be ordered "on line" for small money. The resistor pack no longer is available from Volvo.
Hope this helps.
Yours faithfully,
Spook
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Hi Spook,
Thanks for all your input. Mechanic friend of mine came by today, banged the heel of his hand on the fan motor and it came to life. Works on all five settings. I should remember that this car sat around for almost a year before I bought it.
muskox37
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The tapping worked for about a week but now that no longer works. The fan does not come on no matter what position I choose for it and no matter where I tap the motor.
I rechecked both fuses and both are good.
So now the snag is manifesting as some kind of corrosion/looseness that I was able to overcome by tapping the body of the motor. But now it has settled in and the fan will not come on.
I would describe it as an intermittent problem that has progressed to a full on snag. I will see what I can find but it looks like I will have to start removing the fan blower assembly to see what is sticking or open.
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Dear muskox37
Hope you're well. The blower motor may be at the end of its service life. Worn motor brushes - through which electricity flows to the commutator (the part that spins) - don't make consistent contact. When that happens, the motor doesn't run.
If a new blower motor works only at one-speed (high), then the resistor pack has failed. The resistor pack's thermal fuze may have failed. A recent thread discussed the thermal fuse specifications. If the fuse is replaced, that might make unnecessary a replacement resistor unit, which part is no longer available from Volvo.
Hope this helps.
Yours faithfully,
Spook
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Hi Spook,
This fan blower ran for about a week with a little thumping from a small rubber hammer I carried with me. Sometimes it started on its own and sometimes it needed the persuasion. It ran on all four settings
Then it shut down on me completely and I am back to trying to find the fault. The heater itself is working and at speed I can feel heat emanating from the dashboard vents.
Both fuses that service the heater assembly are good.
I am familiar with electric motors and their brushes, etc., which could be an issue.
The thermal fuse you mention could have broken as well. I need to find the fuse and get a breakdown on how to get at the fan. Not sure if anybody has posted information on servicing the heater fan on Brickboard but I will take a look around tonight or tomorrow.
Thanks again for your valuable input.
muskox37
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Is your AC control panel has the word AUT (means automatic) on it? If it has then there is no blower motor resistor or thermal fuse installed in your wiring.
To know if your blower motor has issues, disconnect its electrical plug then test it by powering it directly from the battery.
Amarin.
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Not being intimate with the 9-series climate control, I do have some documentation, and with it, a vague recollection that the "computerized" version of this varies the blower speed with a solid-state device (transistor) which, if nothing more than in my mind, had a reputation for developing some easily-rectified solder cracks. To my way of thinking, one of these could be just as susceptible to a "technical tap" as a short brush in the motor might be. I'm sure Steve has preserved all this in his 7/9 FAQs somewhere, but I'll let the OP do the research.
My manual refers to ECC (Electronic Climate Control) and ACC (Automatic Climate Control).
--
Art Benstein near Baltimore
“Never underestimate the difficulty of changing false beliefs by facts.” --- Henry Rosovsky
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I will say that the motor was not obviously noisy when running and it reacted correctly to changes in the controller. My 240 squeaks and squawks and is very obvious. This would point more to the transistor if, indeed, that is installed on this car. I was hoping to go and look for the resistor today after consulting a wiring diagram. Not sure now.
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Dear amarin,
Hope you're well. Volvo VADIS - a Volvo dealer superseded parts/service database - shows that on '92 960s, there's an "MFI module" (Part #1365678, no longer available from Volvo) mounted in the duct between the blower motor and the evaporator housing.
I suspect this "module" is the equivalent of the resistor pack found in 940 climate control systems. I do not know if this "module" has a thermal fuse and if so, whether the fuse is readily replaceable.
Even if the motor runs when powered directly from the battery, brushes "on the way out" will soon fail. The thumps required to restart the motor suggest that the brushes are worn.
Volvo does not list internal parts for climate control blower motors, unlike internal parts for alternators, which are listed (but may no longer be available from Volvo).
Hope this helps.
Yours faithfully,
Spook
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I remarked to Art that the motor is not noisy and does work well when it is "on" instead of being "off".
I wonder if worn brushes would create noise. I would suspect bearings if there was a noise---and given the ability to resume function after thumping it over the last week it could be that the brushes were on the edge of function and have now been pushed over into permanent malfunction. Just thinking out loud here.
This is pointing me towards removal of the blower motor. I will take a look at the manual for instructions on that job.
Thanks for your help again, Spook.
A tip of the hat to Art Benstein and the two other contributors as well.
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Dear Spook,
Googling the part number of the said item showed a black box with aluminium heatsink. The box is installed in such a way that the heatsink is cooled by airflow from blower motor. The box houses a transistor circuit with relays that controls the blower speed.
As such I don't think this is our usual green resistor pack with thermal fuse. The Volvo circuit diagram for ECC system showed the internal circuit of this box without any thermal fuse. Regarding the blower motor I'm inclined to think it could just be seized bearing instead.
Amarin.
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Dear Amarin,
Hope you're well. You're correct as to the nature of the motor speed controller in 960s. I have a couple of these devices, which I think fit 850s: they came with a lot of 940 parts. The 960 motor speed controller indeed may not have the thermal fuse, as air-flow cooling should prevent over-heating of the MFI module.
The bearing could be "on the way out". If so, I'd guess there should be some noise, as bearings "on the way out", usually do not go quietly.
Hope this helps.
Yours faithfully,
Spook
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Dear muskox37,
Hope you're well. The thermal fuse does not "break". If the motor seizes, the fuse could be over-loaded and "burn out". Once the fuse "burns out", it has to be replaced. It will not be affected by thumping on the motor (or anything else).
For access to the heater blower motor, see the FAQs at: https://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#HeaterBlowerMotorReplacement .
Hope this helps.
Yours faithfully,
Spook
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Does this picture show the resistor? Item A has two small Εmm?] bolts holding it on. No torx screws that I can see anywhere.
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hi Spook,
Strange. I always found giggling to be quite effective at fixing car snags.
I was thinking of a message you posted to another heater query about using an anti-corrosion fluid to get rid of moisture at the connector. You advised using the fluid because the corrosion could not be easily be seen by the naked eye.
Regardless, I have attached a revised picture of the heater arrangements,this time with my annotations, and I am guessing that item C is the resistor.
muskox37
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Somehow the picture did not appear with my post. I will try to post it here.
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Are you saying that the resistor lives to the left of the four spherical bulges or to the right? I did not get any text with your message.
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