Skip the auto shop - Our mechanics make house calls

Q: The a.c. unit will not turn on

asked by on

The a.c. won't come on at all. The indicator lights are out or off and if you open the good there seems to be air blowing underneath

My car has 66000 miles.
My car has an automatic transmission.

While it is not unusual for the climate control unit to fail in Mercedes models, the most likely culprit is a system pressure issue. Either one of the pressure sensors in the A/C system may be bad, or the system may have a leak and actually be low on refrigerant or even empty. The A/C system has its own set of diagnostic codes, so you may want to have a service professional diagnose the A/C system before replacing random parts, as they can be quite expensive.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. The a.c. unit will not turn on

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Installing front splitter and rear diffuser

A few quick searches on ebay and google revealed quite a few options for me. The model year split in 2009 which explains why finding this part may be so difficult. For the best results, consult your local Mercedes-Benz dealer...

Q: Automatic rear hatch not latching.

Hi, this comes up often on this vehicle. Mercedes has a technical bulletin for it since it is so common. The most common cause of it is from a programming issue with the rear SAM. This is a module that...

Q: CE Light came on , got it checked and it said PO420. Couple of day later went off and has not come back on. 2011 Jeep Compass

Hi there - yes, it is possible the catalytic converter has lost it's ability to burn residual fuel. This could be due to an engine condition that has clogged the catalyst, or a failing oxygen sensor that is not adequately...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...