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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4487
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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I replaced the AC regulator on my 2006 S430, It worked briefly

Customer Question

I replaced the AC regulator on my 2006 S430, It worked briefly and stopped working, I went on line and was told i have to reset the codes on the climate control, I reset the fault code and it started working, the I checked what I think was the damper code and attempted to reset that code, and the blower went off, and i have not been able to get it back on
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.
Hello, i can help, when you say ac regulator the only thing that makes sense to me is the blower resistor, if you could i would like you to elaborate on the issue and why you replaced any parts . also how did you reset the fault code? do you have access to a scanner , also do you know how to do electrical testing if i give you some things to test?
Customer: replied 1 year ago.
yes the blower resister, I replaced the resistor because i checked the fan with a battery and it worked (works) so researching online brought me to the resister, I further researched why the fan was not working after replacing the resister and once again online (you Tube) showed me how to reset the codes by pushing the left and the right auto buttons then holding down the rest and the pollen filter button until the fault code came up, then push the left button in, then the right and the fan started working, then I went a step further (I don't know why i did) and followed the online direction to reset the codes by pressing reset button and the circulate button, then that was it, the fan went off
Customer: replied 1 year ago.
Initially when i installed the resister, the fan worked for 2 days, then went off again, I thought it was a bad part so I got another resister
Expert:  Lou P. master tech replied 1 year ago.
ok, we usually replace the blower and the resistor at the same time, they usually fail soon after each other, since ,have you tested for power at the blower to make sure the resistor was not sending power? there are no fault codes that will cut out power to the fan. fyi. the fan will always work. unless there is a issue with it or the resistor.
Customer: replied 1 year ago.
I have tested the main wiring going into the resister with a volt tester,initially on one leg it read 13, on the second leg it read 6, the after the attempted reset it now reads 9.1 and 4.4 with the fan button on high
Customer: replied 1 year ago.
The fan was working as soon as i reset the code the first time, it wasn't working before i set the code
Expert:  Lou P. master tech replied 1 year ago.
what happened before doesnt matter, what matters now if we get power at the blower and then we check again at the resistor.
Expert:  Lou P. master tech replied 1 year ago.
red wire with yellow stripe should have battery voltage, brown wire is ground, grey wire with green stripe is the speed signal from the control unit, we are not concerned with that as of yet.
Customer: replied 1 year ago.
Why would the voltage readings change from before and after the reset?
Expert:  Lou P. master tech replied 1 year ago.
again, we are not concerned with that right now. it doesnt matter until we verify we have proper supply voltage.
Customer: replied 1 year ago.
Ok, I will test the voltage to the fan, coming out of the resister
Expert:  Lou P. master tech replied 1 year ago.
ok also the wires i described to you are the power wires going into the resistor that we need to check as well.
Expert:  Lou P. master tech replied 1 year ago.
i have to go for the night, i will check back in the am, feel free to message me anything you find, i will see the messages in the morning, i will also send this as a answer so if you find a issue with the power supply and get it fixed then please rate me, if not no worries, we will figure this out tomorrow. have a good night. Lou P.
Customer: replied 1 year ago.
Hey Lou
Customer: replied 1 year ago.
I put a new resister in and nothing, I put the battery to the fan again and it worked, I tested the voltage coming out of the resister and unless i did something wrong, it read 1.7,
Expert:  Lou P. master tech replied 1 year ago.
Ok let me see. There are 3 wires on the resister correct ? There should be power ground and signal speed. So make sure we have ground and power that matches the battery voltage.