View Full Version : Electronic assistance with climate control

One call a/c
01-02-2017, 01:56 AM
Hello sprinter spectaculars

I am in a pinch and need some assistance.
I took out my climate control to replace the bulbs and while inside I also wanted to resolder the relay for the ac compressor. Well while I was attempting to remove the right side stubborn bulb I managed to knock one of the diodes off the board. So I carefully placed the diode back on the solder pads to confirm position. It seemed to be correct but after resoldering and testing I noticed a electronic burning smell so I turned it off. After removing the front cover I noticed another diode cracked / popped. I would like to replace both to be safe and am looking for electronics expertise to order / place them properly.

01-03-2017, 05:05 PM
This should help you some.


There are other guides available for SMB components.

Once you have the component identified, Digikey or Mouser should have what you need in stock.

The 752a might be a 7.5V 0.3W zener diode The other I didn't see listed.

One call a/c
01-03-2017, 05:32 PM
Awesome. Thanks for replying. I will check that out.

01-03-2017, 06:08 PM
Once you identify a compatible part, make sure of a couple of things:

- polarity matters with diodes, make sure to mount the new diode in the same orientation as the old diode. A band usually indicates the cathode, check the datasheets to make sure

- use as little heat as possible. Too much heat from soldering can destroy a semiconductor

One call a/c
01-03-2017, 06:21 PM
Thanks for the tips Ben. I think that's where it all went wrong. A simple changing of a bulb caused this headache. I thought I had the diode placed where it was but guess not. Can you test the diode ? After I knocked it off the board I tried testing with a digital meter set to ohms and didn't get a reading either way.

One call a/c
01-03-2017, 07:00 PM
I now see that there is a "K" on the board at each diode to show which side the stripe is on. So I now know I soldered it backwards the first time [emoji53]. I have order some diodes now I wait. I will update once their in - pun intended lol

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01-04-2017, 06:18 PM
Good work. Nice that you have found the problem. A backwards diode tends to cause havoc and smoke.

Its sort of a pain to test diodes only with an ohmmeter. Better to test it with a diode setting, if your meter has it.

Here is how Fluke recommends testing a diode with an ohmmeter:

The resistance mode procedure is conducted as follows:

Make certain a) all power to the circuit is OFF and b) no voltage exists at the diode. Voltage may be present in the circuit due to charged capacitors. If so, the capacitors need to be discharged. Set the multimeter to measure ac or dc voltage as required.
Turn the dial to Resistance mode (Ω). It may share a space on the dial with another function.
Connect the test leads to the diode after it has been removed from the circuit. Record the measurement displayed.
Reverse the test leads. Record the measurement displayed.

Aqua Puttana
01-04-2017, 06:44 PM
... A backwards diode tends to cause havoc and smoke.

Here's to hoping the resulting problems are only within the diode bridge proper. :cheers:

One Call,
While you have the ATC disassembled maybe you can add some info and pictures to another thread. I posted some alternatives for replacement lamps. It would be nice to get any incorrect parts off my list of possibilities.

The post is here.

Thanks in advance.


One call a/c
01-08-2017, 01:10 AM

I finally got the new diodes in and installed. Everything is working as it should. Thanks to all that replied.

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One call a/c
01-08-2017, 01:45 AM

I also changed the leds in the cluster and shifter to green. Thanks to seek for the write up [emoji1303]

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Aqua Puttana
01-08-2017, 06:02 AM
I also changed the leds in the cluster and shifter to green. Thanks to seek for the write up [emoji1303]

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The dash cluster looks very different, but good. :thumbup:


01-08-2017, 09:56 AM
I can hear somebody, somewhere, abruptly announcing "Well, 'dats what 'yer git for fixin somethin dat ain't broke mmhm!"

One call a/c
01-08-2017, 12:28 PM
Hahaha. Yup. I can see the that coming [emoji6]. But it was worth it. The green looks so much better in person.

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01-08-2017, 04:53 PM
i admit i'm a bit green myself :) i've got one side of my temp dial out

One call a/c
01-08-2017, 07:57 PM

Theses are the part numbers if your interested in ordering the leds. I posted green and red- blue courtesy of seek [emoji1303]. I used the greens in place of the blues that seek used and did the same red for gauges and low fuel

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