AC not turning on. Turns on when it feels like it...
Thread Starter
Junior Member
Joined: Aug 2010
Posts: 26
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C300
AC not turning on. Turns on when it feels like it...
Hey guys! 2004 G500 here with AC issues. I turn the knob for AC to start and no chance. I then press the “auto” button and begins to blow for 2 seconds and shuts off.
After 10 min of back and forth playing the ac turns on and stable. What could me the issue? Blower Motor regulator? The AC blows cold so I’m good there...
please help! Thank you fellas!
After 10 min of back and forth playing the ac turns on and stable. What could me the issue? Blower Motor regulator? The AC blows cold so I’m good there...
please help! Thank you fellas!
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
Turn off the A/C, set the temp for full hot (to call for heat) and then see if the manual fan speed adjustment works. Then see if "auto" works. If it does, the blower regulator is probably not the cause.
Another common issue is that the switches and buttons on the HVAC control unit get dirty and flaky with age which can cause intermittent operation. I'm not sure if they can be cleaned. As an FYi, if you end up replacing the control unit, you can upgrade to the all digital version from the W202 - plug and play (I did it). The digital version also allows for HVAC error codes to be read right from the display.
Check you refrigerant charge. If it is low, the low pressure protection switch may be triggering until the system builds up some pressure.
Another common issue is that the switches and buttons on the HVAC control unit get dirty and flaky with age which can cause intermittent operation. I'm not sure if they can be cleaned. As an FYi, if you end up replacing the control unit, you can upgrade to the all digital version from the W202 - plug and play (I did it). The digital version also allows for HVAC error codes to be read right from the display.
Check you refrigerant charge. If it is low, the low pressure protection switch may be triggering until the system builds up some pressure.
Thread Starter
Junior Member
Joined: Aug 2010
Posts: 26
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C300
Thank you for your direction brother! Will follow what you said. I like the idea of the digital display.
So I went ahead and turned the temp all the way heat on both knobs and turned the fan to see if it will begin to blow. Nothing came out. Pressed Auto and no action as well.
What do you think now?
So I went ahead and turned the temp all the way heat on both knobs and turned the fan to see if it will begin to blow. Nothing came out. Pressed Auto and no action as well.
What do you think now?
Last edited by imortalo8; Jul 20, 2020 at 11:24 PM.
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
Thank you for your direction brother! Will follow what you said. I like the idea of the digital display.
So I went ahead and turned the temp all the way heat on both knobs and turned the fan to see if it will begin to blow. Nothing came out. Pressed Auto and no action as well.
What do you think now?
So I went ahead and turned the temp all the way heat on both knobs and turned the fan to see if it will begin to blow. Nothing came out. Pressed Auto and no action as well.
What do you think now?
Super Member
Joined: Feb 2020
Posts: 849
Likes: 507
From: NJ/NYC
2005 G55K
FCPEuro has these pars with a lifetime warranty. Prices don't seem too out of this world but I haven't done any pricing research. These are listed for my 2005, but should be the same for yours.
https://www.fcpeuro.com/Mercedes~Ben...t=5&b=11&d=&v=
https://www.fcpeuro.com/Mercedes~Ben...t=5&b=11&d=&v=
