Mongo

Magically, my fresh air blower and climate control unit isn't working. I tried to turn on the heat and it seems like no power is getting to the fan.

However, when setting the adjuster to defog, the blower comes on full blast and starts to heat up. Great I'm guessing the fan isn't dead, but is this weirdness with the 1-4 fan speed **** not working? The unit still lights up though, but I can't get the damn thing to turn on normally. If it's illuminating and the windshield defogger works, I take the fuse or relay isn't bad?

CJ8 2 928

Sounds like the a/c Blower Resistor Pack part #er 928-616-101-00.
Good Day Sir

Mongo

Wow do those things go bad from one day to the next? It was working fine on Tuesday.

dr bob

Andy--

The blower is powered through the Defrost Relay at full speed when you select defrost. The rest of the time it gets power through the blower switch and the resistor pack. Both power through the same fuse so that's not the problem.

Popular issues include a loose connector on the control head, the one on the driver's side up close to the face of the controller. If you've had the control head out or messed with wiring in the console lately this is a place to look. Access is through the side cover on the driver's side. You can reach up in there with a couple fingers and see if teh connector is still seated.

The other popular issue is a fault in the resistor pack, or a loose/corroded connection to same. You mentioned previously that the car was wet under a tarp, so there's a chance that the corrosion devils are at work on the resistor or the connector from all that moisture. You can pull just the connector off and verify voltage at the pins with a meter or test light. The pack itself is easy to change if you have a screwdriver (#2 phillips stubby), one of those flexible grabber-type parts pick-up tools, and a hefty hemostat. Reach through the blower boot area (boot retracted( and grab the resistor pack in place with the pick-up tool. Unscrew the old one and withdraw it with the tool. Grab the new part with the same tool, and pass it back towards the mounting position. Use the hemostat to grab one of the pins through the mounting hole, lock the hemostat, then pull the pack into place so you can get the screws back in. Note that new replacement resistor packs are wired slightly differently, you'll need to swap a couple wires in the connector to get a new one to work right. The Tips Pages have the connection details.

Mongo

Damn you are a book of knowledge. Thanks!

Alan

There is also the seperate blower relay - I'd check that first - just swap it with the horn relay (if the horn works).

alan

dr bob

Andy, on your car the Fresh Air Blower Relay that Alan refers to is in position X, and pretty much carries power for everything the HVAC control head does. If the AC button is not functioning, that would be a telltale this relay isn't functioning. Standard 53B relay if you need to replace it.

I have a book of knowledge. I finally got around to loading Jim's WSM CDs onto my laptop. The wiring diagrams are just a few clicks away. Makes it too easy to look smart!

Mongo

I should have pressed the AC button to confirm it. Will try a relay swap tonight to verify the resistor pack has failed or not. Can I repair my resistor pack or do I have to buy a whole new one?

Man corrosion is really getting to my car thanks to these rains I'm glad they are over for now.

Mongo

Great, now I'm all excited to actually start tearing this car apart again.

I can't wait to get this car's blower box completely resealed and the electricals cleaned up. I'm sure it will be like a brand new car!

Thanks for everyone's help as always!

Fogey1

Search for "magic blower" in thread titles.

dr bob

I think this problem is pretty much the opposite of "Magic Blower Syndrome" With MBS, the blower will go to full speed somewhat randomly, and retain all other speed functions intact. From the described symptoms, the blower doesn't run at all except when the temp slider is set to 'defrost' position. The other control head functions are dead.

WallyP

On the '87:

If the blower does not run at all (no run on any of the four speeds) with the lower lever in any position, including DEFROST, check Fuse #17. If the fuse is good, the blower motor may have failed.

If the blower will not run on any of the four speeds, but runs at full speed on DEFROST, the blower relay (Relay X) is faulty.

If the blower will run on the highest speed setting and on DEFROST, but not on any lower speed setting, there is a fault in the resistor pack (usually a broken wire). Sometimes, but less often, the blower will run on the top speed and the next lower speed, but not on the lowest speed, and this is also usually a fault in the resistor pack.

Bill Ball

Oh, how I wish it were that easy! Having the wiring diagrams handy and being able to decipher them are two very different things.

dr bob

Part of the pleasure of having the RL resource is the complimentary knowledge cached around the group. I looked at one thing based on a too-quick read of Andy's symptoms. Hip shot suggestion based on that. Alan looked at it a little diferently and pointed to a better possibility, one more closely aligned with the stated symptoms. Wally bundled a very well-reasoned symptomatic troubleshooting/diagnostic method. And my feeble memory has you, Bill, circulating colored markups of wiring diagram details to help someone understand an electrical problem.

I should have looked up to the wall here, to see the words of JB... Relay-relay-relay.

Amen.

928@AMG

Hello @ all,

I have actually a problem with the blower fan/resistor pack.
Car is an 1981 model.
Last week one of the resistor wires on a new resistor pack melted suddenly. That resistor pack was included in a new aircon box I've installed last month.
I replaced the damaged resistor pack with a only 3yr old reserve part, with modified bi metal as described here.
Also I checked fuse 17 and the blower but didn't find anything. The blower was refurbished/cleaned with new motor 3yrs ago. Worked fine always without any squealing noises.
Btw the blower was not removed during the install of the new aircon box.
Yesterday on a test drive the blower didn't work about 10min after start. Outside temperature was about 30°C - hot summer day
First the blower still ran for 1-2 seconds with the **** on lvl 4, simultaniously to bumps on the road, some minutes later it didn't work anymore except on defrost position.
Aircon was still working good.
Directly after I came back home again, I changed the rly defrost and blower with each other - nothing, blower isn't working except at defrost.
This early morning when I turned on ignition the blower works fine again as it should be, on all four levels.
Update: afternoon time after some hours in hot sun, same problem as above . Blower doesn't work except on defrost.
Seems to be sth wrong with the resistor pack... but exactly this resistor worked without any problems three yrs?
Now I'm clueless ... any ideas about a possible fault ?

Known facts :
Fuse 17 removed/checked and ok.
Rly blower and defrost checked and ok.
Blower motor is working without squealing sounds
Resistor pack is in good condition

Thanks in advance for help