Vehicle: 2018 BMW 330i xDrive Sedan, AWD (F30), L4-2.0L Turbo (B46O)

Mileage: 46,778

Problem: The customer brought their Beemer in because the A/C was not working. Another shop had already replaced the expansion valve and recharged the system but that did not fix the problem.

Case Details: A diagnostic trouble code (DTC) 801224 - A/C compressor: Deactivation due to overpressure in refrigerant circuit, was found in the HVAC module. Not having a lot of experience with BMW air conditioning systems, the technician called ALLDATA Tech-Assist for some diagnostic help.

The consultant advised to first verify that the proper amount of refrigerant was in the system. If the refrigerant level was correct, then use a scan tool to look at HVAC module perimeter identification data (PIDs) for abnormalities in the various sensors (such as ambient temperature, evaporator temperature, and pressure sensors) and look for an A/C request. Also, make sure the condenser cooling fan (if equipped) was coming on.

Another important thing the consultant advised was checking the low temperature radiator. This vehicle is equipped with two radiators, a high temp and low temp radiator. The A/C condenser is in front of both, and the low temperature radiator is sandwiched in between. If the low temperature radiator pump (electric) or the radiator itself is leaking or damaged, that could cause A/C issues.

The technician found out the car had been to another shop for cooling system repairs. The low temperature radiator was never refilled.

Confirmed Repair: He refilled the low temperature radiator and bled the system. Afterwards, he reset the A/C module and went on a road test. No further issues. Fixed!