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Climate Control Unit Replacement
 
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Pelican Technical Article:

Climate Control Unit Replacement

Kerry Jonsson

Time:

2 hours2 hrs

Tab:

$750

Talent:

***

Tools:

T30 Torx driver, T10 Torx driver, plastic door panel removal tool, flathead screwdriver, flashlight

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Climate control unit, loud speaker, center air register

Hot Tip:

When levering out plastic pieces use a rag to protect the trim panels

Performance Gain:

Replace non-functioning climate control unit

Complementary Modification:

Apply protective coating to dashboard to prevent cracking

If you own a Mercedes Benz it is probably because it is one of the most technologically advanced vehicles on the road today. Their climate control systems do offer many different comfort options for the vehicle occupants. There are single zone basic temperature controls but most of those vehicles did not make it to American showrooms. They also offer dual zone (driver side and passenger side) independent temperature control. As an additional option each rear seat can set its own temperature control on the four-zone system. These systems have independent sensors in each air duct providing feedback of air temperature leaving the air duct. If the air temperature were to change the climate control unit would change air blend and mode door positions. The climate control unit is built into the climate control switch panel mounted in the center of the dashboard above the radio. If this unit were to fail you would not be able to control any temperature, mode door and blower motor speeds at all. This is one of the problems of a computer controlled system. When it fails the entire unit has to be replaced. In this tech article we will go over the steps to replace you climate control unit.

This picture illustrates the dashboard just above the ignition switch.
Figure 1

This picture illustrates the dashboard just above the ignition switch. Using a plastic prying tool lever the wood trim strip just above the ignition switch (red arrow). Do not lever at any other point of the wood trim strip, only the left end of it behind the steering wheel. The blue arrows point to the style of the clip securing the trim. Further down the wood trim, the style of clip changes. See the following step.

Slide the entire wood trim strip in the direction of the red arrow a few inches then pull the wood trim strip away from the dashboard to remove it.
Figure 2

Slide the entire wood trim strip in the direction of the red arrow a few inches then pull the wood trim strip away from the dashboard to remove it. The blue arrows show the clip used on the remainder of the wood trim. They engage a slot in the dashboard. These clips detach by sliding them out into the slot, then pulling the trim piece away from the dashboard.

This picture illustrates the center of the dashboard below the heater control panel.
Figure 3

This picture illustrates the center of the dashboard below the heater control panel. Remove the two T30 Torx fasteners (green arrows) under the wood trim strip you have just removed. You do not need to remove the radio/navigation unit to do this job but we have done so for photographic purposes.

Using a small, thin pick or flathead screwdriver insert it into the second slot from the front of the center dashboard grille and three over from the right.
Figure 4

Using a small, thin pick or flathead screwdriver insert it into the second slot from the front of the center dashboard grille and three over from the right. This is the only slot you can use to lever the release mechanism from. You will also need to release the other side of the center dashboard grille by inserting the pick in the slot second from the bottom and the third slot from the left. Here we are illustrating the same procedure on the right side of the center dashboard grille.

Lever the pick upward until the locking tab on the center dashboard grille is released from the dashboard.
Figure 5

Lever the pick upward until the locking tab on the center dashboard grille is released from the dashboard. Do this for the locking tab on the left side of the center dashboard grille as well.

Lift the center dashboard grille upward and pull it toward you to release the back of the center speaker grille from the dashboard.
Figure 6

Lift the center dashboard grille upward and pull it toward you to release the back of the center speaker grille from the dashboard.

Remove the two T30 mounting fasteners (green arrows) just above the air register.
Figure 7

Remove the two T30 mounting fasteners (green arrows) just above the air register.

This picture illustrates the center of the dashboard near the base of the windshield with the center dashboard grille removed.
Figure 8

This picture illustrates the center of the dashboard near the base of the windshield with the center dashboard grille removed. Remove the two T30 fasteners (green arrows) for the loud speaker.

Pull the loud speaker out of its opening in the dashboard.
Figure 9

Pull the loud speaker out of its opening in the dashboard.

Unplug the electrical connector for the loud speaker by squeezing the connector (green arrow) and pulling it away from the loud speaker in the direction of the blue arrow.
Figure 10

Unplug the electrical connector for the loud speaker by squeezing the connector (green arrow) and pulling it away from the loud speaker in the direction of the blue arrow.

Slide the entire air register/climate control unit out of the dashboard to expose the electrical connectors.
Figure 11

Slide the entire air register/climate control unit out of the dashboard to expose the electrical connectors.

Unplug the smaller of the two electrical connectors (green arrow) from the climate control unit by squeezing it and pulling it in the direction of the blue arrow.
Figure 12

Unplug the smaller of the two electrical connectors (green arrow) from the climate control unit by squeezing it and pulling it in the direction of the blue arrow.

Unplug the larger of the two electrical connectors by pushing in on the locking tab (green arrow) and sliding the locking lever (yellow arrow) in the direction of the blue arrow.
Figure 13

Unplug the larger of the two electrical connectors by pushing in on the locking tab (green arrow) and sliding the locking lever (yellow arrow) in the direction of the blue arrow.

With the locking lever pushed all the way down to the bottom unplug the electrical connector by pulling in the direction of the blue arrow.
Figure 14

With the locking lever pushed all the way down to the bottom unplug the electrical connector by pulling in the direction of the blue arrow.  

This picture illustrates the back of the air register/climate control unit.
Figure 15

This picture illustrates the back of the air register/climate control unit. Remove the nine T10 fasteners (green arrows).

Unplug the electrical connector on the back of the climate control unit, on the left side, by squeezing the locking tab and pulling the electrical connector out of the climate control unit.
Figure 16

Unplug the electrical connector on the back of the climate control unit, on the left side, by squeezing the locking tab and pulling the electrical connector out of the climate control unit.

Separate the climate control unit from the air register.
Figure 17

Separate the climate control unit from the air register. Installation is the reverse of the removal steps. Fit the new climate control unit in the air register assembly and tighten the nine fasteners. Plug in all three electrical connectors in the back of the climate control unit. On the larger connector make sure the locking lever is all the way down, push the electrical connector into the climate control unit and lever the locking lever towards its original position. As you do this the electrical connector will be drawn in to the climate control unit. Slide the climate control unit/air register into its place in the dashboard. Plug in the loud speaker, fit it into its opening in the dashboard and tighten the two fasteners. Tighten the two fasteners just above the air register and the two fasteners just below the climate control unit. Install the center dashboard grille by laying it flat just ahead of its normal position and sliding it towards the front of the car until the rear locating tab and two front locking tabs fit into their slots. Install the wood trim strip in the dashboard. Slide it slightly to the left and push the left end into the dashboard until it is fully seated.

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Comments and Suggestions:
Bob Comments: Turned out to be the front SAM. Had to get a new one. Must have been some issue other than the driver chip which I replaced.
November 4, 2016
  Followup from the Pelican Staff: Thanks for the follow up. - Nick at Pelican Parts  
Bob Comments: Tested the old heater control valve on the bench. It works.
Opened up the area where it lives again and connected it to the wires. Turned on car and rotated the temp controls to full heat and full cool. The valve never actuated on way or the other. Checked the voltage to the valve. It's 0, never changes. Pulled the front SAM and replaced the driver chip for the heater control valve. Put it all back together, still no power to the valve. I'm at a loss. What else is left? Valve, driver chip, inside temp sensor all seem to be ok. AC works. Heat doesn't.
October 23, 2016
  Followup from the Pelican Staff: If no voltage change the valve, the module or control is faulty. Check a wiring diagram to determine the routing of the circuit. - Nick at Pelican Parts  
Bob Comments: I am planning on checking that tomorrow.
Pull the drain cover off the heater control valve access area again and plug the wire into the old valve and see if the valve opens and closes. I looks like there is a pump of some sort by the radiator that circulates the hot water to the heater control valve? Perhaps that is bad. I suppose the core could be plugged or is there some ducting that has to open inside the car to let the air flow over the core? Thanks for your suggestions!
October 21, 2016
  Followup from the Pelican Staff: Could be plugged, there are flaps that direct air flow. - Nick at Pelican Parts  
Bob Comments: I'm trying to figure out why I get no heat on my 2004 E320 4matic wagon a/c works fine. Coolant level is good. Replaced the heater control valve with no change. Suspect this control unit or perhaps the temperature sensor but I can't figure out where the temperature sensor is. Any suggestions?
October 19, 2016
  Followup from the Pelican Staff: Have you confirmed the heater core is getting hot coolant through the valve? - Nick at Pelican Parts  
Dalvair Comments: So far excellent
October 8, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Clive Comments: This information is helpful however my e320 is right hand drive which is no problem but the grill section above the climate control is actually mesh and not as illustrated. Can you help with advice as to how to remove the mesh. I have the trim section out ok
June 24, 2015
  Followup from the Pelican Staff: Not familiar with that style. It may come off as a complete piece with the vents. - Nick at Pelican Parts  
Clive Comments: Most helpful thank you
June 20, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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Page last updated: Wed 12/7/2016 02:43:21 AM