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#1
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1985 560 SEC - Automatic climate control works sometimes!
My AC / heater control unit (the automatic one) doesn't work. But sometimes after a long trip, it suddenly starts working again, high / low speed work fine. Then later, dead.
What the hell? Is it the AC relay or can it be some other gremlin? |
#2
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The silver temperature regulator box behind the glovebox is dead. When they go, it results in erratic fan control that occasionally works, and lack of temp regulation (hot/cold only, or stuck in one mode). There are capacitors in it that leak and eat the copper traces off the circuit board.
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Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#3
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Thanks I will check that out!
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#4
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Quote:
This. OP, you may as well have the relay box rebuilt and the PBU while it is down.
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I'm not a doctor, but I'll have a look. '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG] |
#5
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And when you have the push button unit, blower, and temperature relays out rebuilding these isn't difficult.
There's a protective coating on the backside of the boards that can be removed with acetone. It's a pain in the rear, but required. Use a voltimeter to measure the resistance on each capacitor. If it doesn't match what is posted, desolder and replace. And while you're in there, make sure you reflow all of the solder joints one by one as they can crack. If this sounds long, arduous, and annoying do what I did and send it to this guy: Cruise Control Repair He is forum member JamesDean. He did a great job with my boards. I paid him $150 for the whole job.
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-Typos courtesy of my mobile phone. |
#6
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Behind the dash picture
Ok so I couldnt find and silver temp regulator box, neither the vacuum block and some of the vacuum clocks needed. If any of you have anything lying around for sale I would greatly appreciate it! Last edited by olevik; 04-20-2019 at 11:05 AM. |
#7
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Anyone? :O I'm a bit lost here, might try to get a parts car to get everything from. I cant seem to find out is my car should have a silver relay behind the glove box or not. Is this something all cars with auto climate have? Preface and facelift cars?
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#8
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Post a picture of your headunit. Is your car US or ECE?
My 11/84 SD has the early system. My 87 and 90 have late, one of the poster's 86s had late too. |
#9
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I was thinking that black box against the right side lower kick panel area, with the aluminum "ring" at the top was the climate control brain. Is that so, if not, what is its purpose?
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Dedicated to the preservation of antique Mercedes Benz's, one rusty ol' bucket of bolts at a time! |
#10
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Engine ECU. The temperature regulator boxes are not shown in the picture from the OP. He'd help himself a lot if he'd post a picture of which climate control unit he has.
__________________
Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#11
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Plugs are on top, he has a second generation setup. No external boxes! Also explains why has the later front flap assembly.
I only know because I found more PBUs around the house today. Problem solved on identification!
__________________
I'm not a doctor, but I'll have a look. '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG] |
#12
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These pushbutton units frequently have cracked solder connections on the pushbutton switches and temperature dial potentiometer resulting in intermittent operation.
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#13
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thanks!
Thanks for enlightening me about that! Good to know!
__________________
Dedicated to the preservation of antique Mercedes Benz's, one rusty ol' bucket of bolts at a time! |
#14
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thanks for all the input. The car is a Japan delivered car, second gen, 1986 560. Japan cars have the same smog setup as US cars, log exhaust manifold etc. This makes me think its similar to US cars, except the big bumpers.
This is the PBU, it does not have a part number |
#15
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I tried with a different PBU but it didnt help. Dunno if that PBU worked or not! Resoldering the PBU could be an option, if I can figure out how to open it :/
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