Thaddeus

I was warming Sharky up today... turned on the heat. Nada.

Slid the control all the way over to Defrost: full heat blowing out the top.

What's broken? A relay? The head unit (heavens forfend)?

thanks, did do a search, but only found the inverse problem in the archives (heat but no defrost).

TIA

Thaddeus

ErnestSw

The vacuum actuator that works the flap is fried.

Thaddeus

It's not a flap thing. There's no fan when I'm trying to get the heat to come on, twiddle the speed **** however I may. But slide the dingus to defrost, and voila! the fan is blowing.

ErnestSw

Sounds like the AC controller.

SharkSkin

There is a resistor pack that controls fan speed -- it lives in the air plenum under the rain shield. If it fails, then your fan will only work when the resistor pack is bypassed -- e.g. defrost setting. Double-check it before you spend the $$ though.

Thaddeus

Mrmerlin

Hey Thad, check your relays, there are 2 that will send power to the fan blower # V the igntion relay and also find the blower relay, I think they are both #53 relays so they can be swapped with the horn relay also check the fuses and last but not least open up the front cowl cover under the hood and look in the middle you will see a blower duct and look for the big harness that goes to the front side of the blower duct this is the harness that plugs into the resistance group, to remove the group it is pretty easy you need a magnet and a phillips screwdriver remove wire harness, carefully remove the bottom screw with the magnet standing by then the top screw, slide the group to the pass side then pry open the rubber bellows and try to fish it out with a pair of needle nose pliers i use a stiff piece of wire to move it thru the duct then you can test the different circuts if you look carefully they are labeled in the group as to what there resective resistance should be . Stan

Thaddeus

This resistor pack people speak of... is it a seaparate component or part of the fan assembly? And how wold one go about troubleshooting the resistor pack?

Some input from the gurus would be much appreciated...

I am also wondering... if MICE haven't gotten in somewhere and nibbled at somethingthey oughtn't have... I was peeking here and there, but see no eviidence of their presence...

jeff jackson

The resistor pack is a separate part. It is situated inside the evaporator ductwork, about 8" from the rubber sleeve that connects the duct to the blower motor proper. This is in the cowl, below the windshield, near the wiper motor and linkage. If you look closely at the duct, you will see an electrical connector very close to the evaporator "freeze swtch". This connector plugs to the back of the resistor pack. You can diconnect the connector, remove the mounting screws, and then...the resistor pack is too large to come out of the hole its mounted to, so you have to gently pry apart the rubber seal that connects the ductwork to the blower motor, (which is at the passenger side of the cowl, below the wiper blade). Once the rubber seal has been dislodged...you can reach up into the duct and extract the resistor pack. The resistor pack can be checked with a volt/ohm meter for proper resistance and continuity (Specs are in the WSM). If damaged or borken, replacement can be had from the big 3 vendors. A bit pricey for what it is though. PM or email Gary Knox on this board. He has a very nice 88 he's parting right now, and could probably provide you with a excellent used part very reasonably.
Jeff

John Struthers

I believe there are sensors -or is it that resistor pac?- that sit at either end of the slider slot.
Is the slider "sloppy"?

SharkSkin

The connector for the resistor pack is shown in the pic below; it is the rectangular connector just below the round vacuum servo at the far left of the pic.

Thaddeus

Well, Merry effing Christmas to me. Old Saint Ferdy just slid down my chimney and left another electrical gremlin-turd on my hearth.

Ho Ho HO.

karl ruiter

It is certainly the resistor pack. Like the outer door handle pivot they pretty much all fail at some point. 928 intl shows the part (I think) as 928 618 101 01, for $130. Double check with Jim. I think that is a new part and they have used parts for less. Replacement is not too bad. The worst part is that you have to pull the blower motor first, which can be a pain. Not a lot of fasteners, but hard to jockey it out of the hole. I think I recall that I pulled the hood prior to pulling the blower and that this made the process easier, but then you have to re-align the hood and that is a pain also. Once the blower is out of the way it is pretty easy to change the pack, if you have reasonably small hands, which I do not. Another thing that was kind of a pain is that there is a rubber boot that connects the blower motor to the plenum that is tough to get in place as you jockey the blower back into position. Perhaps that was the reason
I ended up pulling the hood. Overall you are probably looking at around $60 plus shipping for the part and 2 hours of work, one of which will not be suitable for mixed company.

jeff jackson

John...
You are referring to the micro-switches that are at either end of the temperature control slider, internal to the Climate Control head unit. These are what work when you have an open control loop, between the cabin temperature sensor, the outside air temperature sensor (in the alternator cooling duct), and the Climate control unit. This is whats referred to as the "majic blower" syndrome...where the fan only blows full speed or nothing, and generally only when in the Defrost program. BTW...I have a good outside air temperature sensor if anybody is needing one to cure this issue.

SharkSkin

I helped Ron_H swap a resistor pack. We loosened the blower motor and jockeyed it to the side a bit and were able to do the job without disturbing the hood or completely remove the blower. YMMV.