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Climate control gremlins
So I was too happy too soon. My climate control was stuck in the defrost position with the fresh air flap open; I took off the dashboard and center console and when I found the mysterious vacuum leak that was ailing my climate control, I repaired it, re-routed the wrong lines and everything was working just fine. Then, as long as I was there, I took off the cheap alarm system someone had clumsily installed in the past. Apparently that caused a couple of electrical problems which new fuses solved. But now my climate control is back to square one at defrost flaps and fresh air flap open. No vacuum leaks this time, when the ignition is off, the whole system holds vacuum quite well. As soon as I open the ignition, apparently power is ran through all 6 switchover valves opening them and losing all vacuum. Also, sometimes when I run the blower at max speed it blows a fuse, especially if the blower isn't working at at least 3rd speed. I'm at my 3rd fuse today. It's intermittent though; if I allow the blower to reach speed 5 and then I hit max speed, it won't blow the fuse. I don't know if the control unit is blown or if the electronic switchgear could have received any damage, but I don't know how to test these two units... Any electronic gurus have any experience with either one?
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#2
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Here's a pic of the unit in question:
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#3
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I just tested all the vacuum and it tests out ok. Not perfect but pretty up to par. The unit I just depicted doesn't sound after all like it would control the switchover valves so my last suspect is the pushbutton control unit. The manual calls for a special tool for testing that thing, anyone knows of an alternative? (also comes to mind the numerous times it blew a fuse when I pushed position 6 on the fan speed button...)
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#4
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I've worked on a few of the first generation w126 climate controls. They are in three pieces. PBU, temperature regulator/vent control and blower motor control.
I seen a one or two of the temperature regulator units with some chips completely blown in half.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#5
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Just opened the unit and it's all good inside. Cleaned it spotless for good measure. The quest continues...
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#6
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Which unit?
Most of the time the problem is with a cold solder joint. They are often difficult to see visually. Also aged capacitors can be a problem too.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#7
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i replaced that temperature regulator unit when i was getting nothing but full heat and it solved the problem, but it wasnt causing any of the symptoms you describe, fwiw
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1981 NA 300D 310k miles |
#8
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I dismantled all 3 components. No minute cracks on cold welds; didn't test any capacitors though but at least they look okay. I'm testing the vacuum switchover valves now.
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#9
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Which fuse is blowing?
From your description, it sounds like a blower motor is on it's way out. Have you pulled it and inspected the brushes and commutator? I've also read here of the electrical portion of the ignition switch causing intermittent problems. Have you noticed anything else giving intermittent problems?
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#10
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This might be useful. Scroll down to "Other Items".
http://tank.windwireless.net/~jimc/ My 85 intermittently blows cold at speed. I've changed the mono valve & swapped a working control unit from the 84SD. Perhaps the temp sensor up near the interior mirror??
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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do. |
#11
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I found the culprit. I was testing the vacuum with the ignition off, so of course I want getting any vacuum leaks with all the switch valves closed. The culprit was the vacuum actuator for the windshield defroster whose rubber diaphragm has a small rip, probably caused by never being used up until just recently, worked fine a couple of times and then tore apart. I don't want to replace all the actuators in the car, but I know they're on their way out. I dismantled this one and used electric tape to patch it up to see if there were any more vacuum leaks and it worked fine. No more leaks. I also know that tomorrow morning my patches will be gone. I've been googling about mending rubber diaphragms and found a couple of good solutions. I'll see of I can find a can of liquid rubber, or rubber in a can or whatever it is that they call it and treat all of the diaphragms this way to prevent also future leaks, see if that works. I'll be posting here how that goes
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#12
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Quote:
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[/SIGPIC]~cirrusman 1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang" [SIGPIC] 1983 Toyota Tercel (Tommy, The little Toyota that could) 1965 Ford F100 (Grandma Ford) 2005 Toyota Sienna (Elsa, Wife's ride) Gone: 1988 Toyota Pickup 2004 Subaru Outback 1987 Cadillac Fleetwood Brougham 1986 Volvo 740 GL Station Wagon - Piece of junk. 1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P. 1987 Pontiac Fiero GT |
#13
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Quote:
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
#14
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Quote:
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#15
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On my dad's SD, i found that the clutch wire for the a/c compressor was damaged and arcing to the chassis. This blew the fuse for the blower motor. Didnt realize this until after I replaced the blower motor.
Also there is a set of resistors under the brake master cylinder that are used for the blower motor. They should be next to the aux fan resistor.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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