Questions and Answers

BMW 528e A/C Blows Fuses Q. Good morning sir, I recently purchased a: 1988 BMW 528e 2.7 liter Automatic transmission 149,000 miles (speedometer broken) ABS P/S, A/C, Cruise control

I bought this car as a gift for my 16 year old daughter and I am trying to get a few bugs, all of the bugs actually, worked out of it. I will start with the air conditioning system. It continues to blow the 25 amp fuse. It works for a little while, not very cold, then the fuse blows. I have numerous other questions/repairs needed, but I will start with A/C.

Thank you!
Robert

A. There is an electric heater control valve that would freeze up and cause the symptoms you describe. The heating system utilizes hot coolant from the engine cooling system to warm air for heating the passenger compartment. The amount of coolant that flows into the heating system is controlled by an electric water valve.

The water valve is electrically actuated. It is located at the left-center back of the engine compartment (beside the brake booster). It controls coolant flow through the heater core.

The valve is powered closed by an electric switch; when not powered, it springs open. The valve, when powered closed, prevents hot coolant from entering the heater core, so the air entering the passenger compartment is not heated, When power is removed, the valve springs open, so that hot coolant flows through the heater core and can warm the air entering the passenger compartment.

If that's not it, you can try unplugging components until you find the one that is causing the fuse to blow. Failing that, you will need to use the wiring diagram to track down the problem.