Skip the auto shop - Our mechanics make house calls

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

asked by on

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.

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

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: Heater still blowing cold air?

When cooling systems are re-filled (after thermostat replacement for example) air can get trapped and that trapped air can prevent normal circulation of coolant. That, and low coolant level, would be the first things to check. If no problem is...

Q: How do you use the heater and air conditioner?

Depending on the trim level of your car, you have either a manual heater and air conditioner or an automatic climate control system. If your system is manual, here’s how to use it: Heat: To turn on the heat,...

Q: Erratic idle - 2013 BMW 335i xDrive

This is a common sign of a dirty or failing idle air control valve. This is a unit that monitors the air intake as it is mixed with fuel prior to being injected into the motor at low speeds or...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...