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  #1  
Old 02-27-2012, 08:03 PM
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1980 240D Heater doesn't work-

So I've done a bunch of research/troubleshooting, and can't seem to figure out why the heat in my car doesn't work. When the heater is on, I can feel warm air inside the vents, but the actual blower doesn't spin.

I got to the blower today, and hit it with a 9v battery, and the blower motor turned without a problem. I then checked the wire going into it with a multimeter (ignition on, all switches pointed to 'full heat'), and there was no power going to it! I noticed that the three dials on the dash all seem to do what they are supposed to (as they are mechanical dials, you can see what they are operating).

I traced the wire from the blower motor back to a 4 pin connector, which is shown in image 098 here : (PeachPartsWiki: Replacing the A/C Evaporator). See the one being hit with the screwdriver here:



I didnt have a wiring diagram, but I used my multimeter under the same conditions as above to look for voltage, and it seems that no combination of wires from the source (hanging wire above the hand in the image) had any power coming from it!

Further, I checked all of the fuses in the box next to the brake booster, and all seemed to be fine. I didn't see anything else in the engine bay that looked like a fuse box or anything, and the 'blower motor resistor' that research shows should be inside the fender, isn't there.

So, anyone have any additional troubleshooting tips I can take?

Additionally: I found a wire with what looks like a BNC connector (screw on single terminal inside) just hanging under the passenger side near the dash. Does anyone know what this is for?


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  #2  
Old 02-27-2012, 08:48 PM
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That's not a BNC. It's a UHF for the no-longer installed car-phone unit. The other end is probably in your trunk.

For your car, per the FSM since I've got no 240 experience, the blower resistors are in the fresh air duct, not on the fender.

Fuse 10 <> is blower, only hot in RUN and START so position II on the ignition for testing. Flow is Battery--->Switch--->Resistors (except for max setting)--->blower. You can check at the switch (pin 1, Bk/Gn/Pk) for +12v.

Link sent via PM.

The manual system is also discussed here. I couldn't really make sense of what was meant by "The wiring harness on the left connects to the fan, the receiver for the four prong dongle thingie, the resistor pack for the fan and a single black(red/green) wire that goes to the A/C thermoswitch (Make a note of this for later)." A bit too technical, I guess.

http://www.peachparts.com/Wikka/W123ACC1Conversion

Last edited by Yak; 02-27-2012 at 09:04 PM.
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  #3  
Old 02-27-2012, 08:59 PM
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Huh, I didn't realize that was even an option, this car seems to amaze me!

Is there an easy way to get into the fresh air duct without having to pull the entire dash apart? The link in mine above seems to imply that the only way to get there is to remove half the car to get the duct out! At the moment, I have the passenger side knee panel out.

I checked for a fuse 16 (I don't have it, but there is a 'd' that is listed as 'auxillary heater fan') that I checked, but it works.

Also, I don't have a heater switch on the dash, it is a mechanical rotary dial that changes the fan speed.
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  #4  
Old 02-27-2012, 09:02 PM
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See above post. I was editing while you replied.

The "aux fan" usually refers to the condenser cooling fan in front of the radiator. Probably a two-fuse deal. Fuse c (or d?) is the power to turn the motor. Fuse 12 should be the electricity to close the relay that lets fuse c route the power. Shouldn't be related to the blower functions
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  #5  
Old 02-27-2012, 09:15 PM
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I read through that link, and it is a bit over my head, but I'm going to keep looking. All the fuses (assuming just the 1 box) work, so I doubt it is that. I'm trying to work backwards from the wiring diagrams, so I think I need to find the blower resistor and ensure that it is OK, though I'm still not sure how/where to find it.

A part of me is thinking about just wiring the blower motor to a switch and pull off of an ignition 12v source somewhere. At least then I'd have heat for the short term, since everything else seems to work fine.
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  #6  
Old 02-27-2012, 09:37 PM
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Quote:
Originally Posted by Keaner View Post
I read through that link, and it is a bit over my head, but I'm going to keep looking. All the fuses (assuming just the 1 box) work, so I doubt it is that. I'm trying to work backwards from the wiring diagrams, so I think I need to find the blower resistor and ensure that it is OK, though I'm still not sure how/where to find it.

A part of me is thinking about just wiring the blower motor to a switch and pull off of an ignition 12v source somewhere. At least then I'd have heat for the short term, since everything else seems to work fine.

It's maybe not as complicated as it looks. If you start at the "vacuum pod in question" line, that pic shows the harness.

At the top right in that pic you've got a 6 pin connector that plugs into your rotary fan switch. Wires appear to be 1) Bk/pk/gn to fuse box - this is the power for your blower - probably fuse 10. 2) Gn/red - this connects to the #3 connector on the 4 -pin dongle thing for the low speed resistor. 3)Gy/Bl for lights off the dimmer 4) Gn/Yl connects to #2 on the 4 pin for medium resistor. 5) Br for ground for the lights 6) Gn/Yl/Bk connects to #4 on the 4 pin and bypasses the resistors for max fan.

The other end of this - the 4 pin on the lower left plugs into the 4 pin on the center right. The Rd and Br two pin off this seems to plug into the fan. So if you traced the Rd and Br from the fan to the 4 pin in the above pic, then you've found all your connections.

In the pic, the female end of that 4 pin seems to be the "upstream" side. Turn the ignition to ON, turn the heat on and the blower to MAX. Then check pin 4. It should have +12v. If it doesn't (and everything above is also correct - which is a guess) then the problem is at the switch (or the fuse). So then work upstream.
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  #7  
Old 02-27-2012, 09:49 PM
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I suspect you've got the wrong pic referenced. I don't think 098 shows the fan plug. More like 120. 122 shows the 240D resistors. Pic 098 appears to be in the driver's footwell.

If you look at pic 090 you can better see the relative location of the plug with some perspective of car locations. It's to the left of the aluminum rectangle (the TXV for the A/C). You can follow the fan wire to the left of the round grommet that is easily visible in pic 120.

PeachPartsWiki: Replacing the A/C Evaporator

Find the female end of that plug and check for voltage.
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  #8  
Old 02-27-2012, 09:54 PM
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I think you're right about the picture. 120 does look like the right one.

I checked for voltage against both a body ground and the ground wire on the plug panel (which interestingly doesn't show up in that picture), and got nothing. I am having a hard time getting to the back of the fan speed switch though, there is a ton of stuff in the way, and it doesn't look like it'll come out the front.

The only thing I see behind it is the mechanical wire pull which goes around the drivers side, and comes around and pulls an arm on the fresh air box.

Thanks very much for the help, I definitely appreciate your help on this.
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  #9  
Old 02-27-2012, 09:58 PM
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Put the voltmeter on both sides of fuse 10 in the fuse box with the fuse installed and the car on. If that gives you power in the in and the out sides, then you may have isolated the problem to the switch itself.

And, don't overlook the obvious, make sure your meter is set correctly and isn't set to auto-sense AC or something (I've NEVER done that...). Measure something that you KNOW works and is in the proper range.
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  #10  
Old 02-27-2012, 10:30 PM
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I was able to get the plug on the back of the switch with much finagling. I came in to write down the wiring stuff you gave, I'll take a look!

The switch is very hidden inside the dash! If it ends up being the problem, I have no idea how to get it out.
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  #11  
Old 02-27-2012, 10:43 PM
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Pic 043 shows the switch and the plug. Probably remove the trim plate (earlier pics) remove the radio, unbolt the switch, drop it down. Or pull the whole console - which isn't that hard either.
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  #12  
Old 02-27-2012, 10:47 PM
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So I figured it out! I went off of your wiring diagram, and was able to get it to work with just the harness (shorting 1-6), then I plugged it back into the switch, and it worked still! I pulled the plug and noticed that the #1 wire was corroded through where it attaches. I was able to pull the switch apart enough to clean/re-solder the connection, and all seems to work.

The only problem I have now is figuring out what kind of fuse it uses, since I popped it while soldering. Hopefully the guy at Napa can tell me in the morning.

Thank you very much for your help!

-Erich
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  #13  
Old 02-27-2012, 11:13 PM
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Assuming it was #10, probably a 16A. They're color coded.

See here, post Fuse box chart, what fuse goes where

There's an '82 240 that says 8 is the blower. Still a red/circle/16 A fuse.
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  #14  
Old 02-27-2012, 11:37 PM
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I bought a 16A fuse, the fuse that was in there was a red 16A fuse, though the wire looked smaller than the rest :/ All seems to work now Thank you again, you were a huge help!

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