Mercedes

Have Mercedes questions? Ask a mechanic for answers ASAP

Ask an Expert, Get an Answer ASAP!

Mercedes AC Compressor Problems

Mercedes AC compressors form an integral part of the car’s air conditioning system. Their exact function is to pump vaporized refrigerant from the evaporator, compress it under high pressure and transfer it to the condenser. The condenser subsequently removes heat from the vehicular cabin. Blower motors also form an important part of this system and problems with the Mercedes AC compressor and blower motors can be interlinked. Issues with Mercedes AC compressor can lead to lack of air conditioning or problems with it which can make driving uncomfortable.

To know more about Mercedes AC compressor troubleshooting, below are a few common questions answered by Experts.

The Mercedes AC compressor and dryer was recently replaced why is the cooling fan running continuously? Is it safe to drive the car?

In this case, the recent Mercedes AC compressor replacement may not be related to this fan problem. I It could be that the fan relay system has failed. On the other hand, it would be safe to drive the Mercedes as long as water is present in the radiator and the car does not overheat. Fans usually come on either if the temperature of the engine is very high or the pressure of the AC system is too high. If the fans turn on as the key is turned in the ignition and despite the car is not operating it is an indication of a malfunction. The other possibility could be a problem with the refrigerant pressure switch in the AC drier. O It could also be an issue with the pressure switch which screws into the drier. A simple test to confirm this would be to unplug the switch to check if the fan ceases.

Why doesn’t the Mercedes AC compressor (300E, 1987 model) turn on? It was functioning fine two days ago, the fuse is good and so is the fan motor.

The most probable reason for this problem would be low Freon. In case there are no AC gauges available to check the pressure in the system, the sight glass in the receiver dryer should be observed. If bubbles are present, the Mercedes AC compressor should be recharged. The second most probable cause would be a faulty climate control relay. This can be found behind the battery and beside the fuel pump relay. Once the AC faults have been dealt with, the fault codes need to be erased using a dealer’s SDS machine or a scan tool. This resets the system and the tool is able to signal/communicate with the heater and AC control unit on the Mercedes, in order to get it functional again.

After the Mercedes AC compressor replacement, why is it blowing only warm air?

If the pressure is normal but blowing warm air, the heater core shut off valve may be stuck. If stuck in the open position causing the heater core to remain on simultaneously as the evaporator is trying to cool the system. To address this problem, first, the AC temperature should be set at “Lo” to allow it to bypass the interior temperature sensors. Next it may be a good idea to replace the heater core shut off valve beneath the cowling under the hood. Additionally the high and low side pressures of the AC gauges should read 90/90 when the Mercedes AC compressor is off. It should read 30/200 when the AC compressor is on and working efficiently.

Why would bumping the wires on AC compressor, cause the loss of cold air with the AC on a Mercedes CLK350?

When the wires were damaged, the Mercedes AC compressor control module may have recorded and stored an “open circuit” code. Hence the first thing would be to try repairing the wires to make them how they were originally. If this does not work, the AC control unit’s fault memory may need to be erased. Without doing so, the Mercedes AC compressor may not turn on. Another option would be to try disconnecting the battery for a minute to check if the fault codes get automatically erased.

Simple problems related to Mercedes AC compressors can be small repair jobs users can take up as a car owner. Even with these jobs, there can be times when needing assistance and information which an Expert can provide. For bigger jobs which involve more complicated replacement and troubleshooting of Mercedes AC compressors, visit the dealer. Users can also take professional advice but Experts can still provide their inputs and opinions on the methods and processes adopted.
Please type your question in the field below

3 verified Mercedes Mechanics are online now

Mercedes Mechanics on JustAnswer are verified through an extensive 8-step process including screening of licenses, certifications, education and/or employment. Learn more

Online
MB Paul

Mercedes Technician

Vocational, Technical or Trade Scho

★★★★★
3567 positive reviews
Online
Marty

Mercedes Technician

Associate Degree

★★★★★
30547 positive reviews
Online
Michael Warfield

Factory Mercedes-Benz Technician

Vocational, Technical or Trade Scho

★★★★★
3132 positive reviews
See all Mercedes Mechanics