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#1
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Diagnosing W124 Climate Control Fault
Here is the issue: 1995 W124 E320, go to turn on heat, nothing. No servos for blend doors, no AC, no fan, nothing, on any setting. Ribbon fuse R15 is fine. Pulled and checked fan motor, works as should. Connections to motor seem fine. Getting solid 12V to red wire at X64 plug on firewall by the brake booster with ignition on, using black in same plug as the ground, however no voltage to Yellow signal wire, on any CCU setting. Replace CCU with 2x known good units, still nothing to Y wire. My understanding is that the voltage to the yellow signal wire that is a "trigger" to the voltage regulator under the fan should be between around 2v at low and 9v at high. I have nothing. What is the next step? (It seems that around the same time this issue cropped up the accelerator kick down stopped working, and to get it to kick down I have to manually shift it into 2 to get passing speed...any connection?!)
Thoughts? At wits end.....! Cheers. |
#2
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Sounds like a fuse problem. Get in the fusebox and check them all closely. They can look good while being bad so use your fingers and get tactile with them.
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90 300TE 4-M Turbo 103, T3/T04E 50 trim T04B cover .60 AR Stage 3 turbine .63 AR A2W I/C, 40 LB/HR MS2E, 60-2 Direct Coil Control 3" Exh, AEM W/B O2 Underdrive Alt. and P/S Pulleys, Vented Rear Discs, .034 Booster. 3.07 diffs 1st Gear Start 90 300CE 104.980 Milled & ported head, 10.3:1 compression 197° intake cam w/20° advancer Tuned CIS ECU 4° ignition advance PCS TCM2000, built 722.6 600W networked suction fan Sportline sway bars V8 rear subframe, Quaife ATB 3.06 diff |
#3
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If the key switch is sloppy, you can overshoot the contact.
Try slowly moving the key back and forth in the #2 position to see if power comes on. Sounds like a power supply issue, if not the switch than start checking fuses. Jim
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14 E250 BlueTEC black. 45k miles 95 E320 Cabriolet Emerald green 66k miles 94 E320 Cabriolet Emerald green 152k miles 85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles |
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