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A/C Temperature Sensor ETR Switch Replacement
 
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Pelican Technical Article:

A/C Temperature Sensor ETR Switch Replacement

Mike Holloway

Time:

1 hours1 hrs

Tab:

$40.50

Talent:

**

Tools:

Flat Head Screwdriver, 8mm Socket, 20inch extension

Applicable Models:

Mercedes-Benz R107 (1972-89)

Parts Required:

ETR Switch, Pelican Part Number 003-820-24-10-M6

Hot Tip:

Label the vacuum lines with a masking tape

Performance Gain:

Improved Cabin Comfort

Complementary Modification:

Replace Vacuum Lines

If your air conditioner is not functioning properly and you have checked the air conditioner for leaks or shorts, chances are good that there is a temperature sensor switch may have failed. In order to get at the temperature sensor ETR switch, the glove box must be removed.

The ETR is designed to shut off the compressor by way of the evaporator. The ETR is located near the evaporator casing. The design utilizes a capillary tube containing Freon gas. The Freon expands and contracts according to the temperature in the evaporator coil. The expansion and contraction action is converted to mechanical action to open and close the electrical contacts, which turn the A/C compressor clutch off and on. The contacts are adjusted at the factory to close at 46F. The ETR can be adjusted to open at a lower temperature and close at another. This allows a cycling of the compressor clutch and providing cool air. As these cars get old, the ETR can experience operation drift or fail entirely. You can improve the ETR cycles by adjusting and cleaning the contact pivots to decrease the span and lower the operating point. In order to do this you can follow the replacement instructions. Chances are a replacement of the ETR is most likely in order.

Before you do any work on your car it is important that you wear safety glasses, work gloves and dispose of all fluids in a safe manner. Coolant is poisonous and should be treated as such. Animals and small children have been known to die from ingesting coolant. If you have to jack up your car, make sure to use jack stands and chock your wheels as well as applying the parking brake. Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability. Always wear eye and hand protection. Disconnect the battery before working on your car.

Using a flat head screwdriver, pry off the plastic fastener which holds the glove box in place.
Figure 1

Using a flat head screwdriver, pry off the plastic fastener which holds the glove box in place. Be careful not to break the inset or the fastener. There will be two fasteners to remove.

Lift the glove box out from the instrument panel.
Figure 2

Lift the glove box out from the instrument panel.

Once the glove box is out, you will see the A/c sensor on the left hand side of the glove box cavity.
Figure 3

Once the glove box is out, you will see the A/c sensor on the left hand side of the glove box cavity. Remove the leads.

Using a Phillips head screwdriver, loosen and remove the front bolt.
Figure 4

Using a Phillips head screwdriver, loosen and remove the front bolt.

Using a Phillips head screwdriver remove the rear bolts which anchor the unit.
Figure 5

Using a Phillips head screwdriver remove the rear bolts which anchor the unit. .

Gently tug on the temperature sensor line.
Figure 6

Gently tug on the temperature sensor line. It can be snaked in after the fact. .




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Comments and Suggestions:
Baxslaw Comments: Nick would there be any sensor controlling vacuum lines that would cause the dash to be removed? Thanks
July 5, 2016
  Followup from the Pelican Staff: Vacuum blocks and actuators can be accessed once removed. - Nick at Pelican Parts  
Baxslaw Comments: Ambient Air Temperature Sensor I had a mechanic tell me they have to remove the entire dash to replace this sensor in my 1981 380sl is this correct.
June 27, 2016
  Followup from the Pelican Staff: Not if it is the sensor shown in the article. - Nick at Pelican Parts  

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Page last updated: Fri 12/9/2016 02:43:50 AM