Heater AC fan intermitent '83 300D
 

I've been kickin this for a while. The fan is a known good one. Once in a while the fan just stops working. Usually after a restart. This happens when you need it most of course. Temps are around 28 degrees in the winter, no fan. 95 and above, nope no fan. Seems like a power issue but it sure seems like it has a mind of it's own.

Any one have a wiring diagram, or funtion diagram of a an 83 300D?

Worn brushes? New ones can be adapted from brushes available at the hardware store.

The motor is fine. Has a ton of brushes inside.

Ok New info

The fan quit working again and I found out that the hot wire to the fan motor went dead. The ground wire for the fan was still at 0 ohms. Few minutes later I hit the defrost switch which makes the fan go in fully the fan is again got power. I've done this before with mixed success. Sometimes it works, sometimes it doesn't. All other functions are working, i.e. vents and AC compressor.

Now that I know it's a power loss to the fan I can always bypass the other switches but I have faith I can fix this correctly,,,, without a bank loan:rolleyes:

Oh by the way it's a 1982 not an 83 300D. Sorry I'm like the rest of you all out here, ADDICTED

High on the list of suspects would be cracked solder joints in the CCU.

I believe there is a fan controller behind the glovebox. If it makes sense the controller would be giving the fan power. I just need to find out what would make it or what ever stop giving the fan power. Fan controller it self, relay to the controller or the push button control unit.

Sure do wish I could see a wiring diagram.

Very unlikely that's your problem. I would recommend opening up the push button unit. Check for problem solder joints and clean the relay contacts on all relays on the board.

Hmm
 

This is a common issue.

Climate Control Repair
on the 1983 300D Turbo (W123 Chassis)
http://www.peachparts.com/Wikka/W123ClimateControl


.

Honestly I've tried that. My circut board relaly does look good at all the solder joints. What are you using to clean the relay contacts? If anything the relay contacts sounds like the culpret.

I've found the wiring harness going from the fan to the controller which makes sense. I'd swear I've heard the relay controller trying to switch but it must thave been my imagination as there is no power to the fan. Once she quits I have to let it be off for a while and it seems to be ok for a while. Exersizing the buttons sometimes makes it quit other times all I have to do is turn the car off.

It really has a mind of it's own

If you bang on it and it gets going... or it slows to a crawl at times, you can bet on the brushes. Especially if the fan is original, they'd need replacement by now. It is an easy fix, there is a guy on the forum that sells inexpensive drop-in replacements.

The fan is fine. I've had it appart and the brushes an so on are like new. this car only has 114k miles on it. The problem is there is no juice coming to the fan at times. So fan controller or what ever is turning it on.

Love to find out which wire powers up the fan controller.

There are only 10 or so terminals:eek:

Kindly explain how bad brushes will prevent power from getting to the fan motor.

Terminal #12.

at a time when the fan is not working, verify that the fan is connected to the chassis, then measure the voltage present at each juncture between the battery and the fan motor. one of them is intermittently cutting out. a cold solder joint, as mentioned, is a likely culprit, but it could also possibly be a dirty switch/relay/fuse terminal.

Anyone have a wiring schematic for an 82?