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Q: What would cause my AC and heater to not work in my 1994 BMW 525i

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My car has been sitting around for about 4 months while having the transmission replaced. Since it got fixed, the ac and heater doesn't work. Air comes out of the vents, but it is just luke warm air no matter what temperature it is set to. The heater and ac worked fine before I got the transmission replaced.

My car has 256000 miles.
My car has an automatic transmission.

Hello. If both of these have not worked since the transmission was replaced then I would start by checking all of the connections that were taken off during the replacement. It is possible that there is a bad ground connection. If all of the connections are fine then the control module may have failed due to the loss of voltage from the battery being disconnected. I would usually start by making sure that the unit is getting voltage and that it is putting out the right signals. If it is then it may just be low on coolant and refrigerant which will keep both of these from working.

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