Skip the auto shop - Our mechanics make house calls

Q: Lost temperature control on hvac

asked by on

Last week I disconnected the battery to clean posts and connectors. Since then I cannot control the temperature. I don't have the electronic push button system. Mine is the knob selectors. I first noticed that it wouldn't adjust for a cooler temperature in the cold weather we were having. Toward the end of the week it had warmed up. I thought I would try the ac. I turned the knob to cold setting and then selected Max Cool. Nothing but very hot air. Turned it off. When I got home, I left the temperature selection to cold. Now I have nothing but cold air. I read somewhere that this could be a simple reset issue after having disconnected the power. But I don't know if that was referring only to the electronic push button system. What I read indicated I will need a mechanic for this step. Does the reset also apply to my climate control system?

Hello, and thank you for writing in. Without knowing the make and model of your vehicle, it is difficult to determine what kind of electrical components we are working with. In general, when the battery is disconnected it can mess with settings with the radio and other presets. In addition it may cause the climate control to become confused about what setting it is set to. Typically regardless of what brand of vehicle you have, it can either be reprogrammed or reset. There are a couple of things you can try before resorting to a technician. They include (depending on make and model) key cycling (turning the key to the on position, or turning the vehicle completely on 3-5 times), driving a certain amount of miles, turning the climate control off and on a certain number of times, or unplugging the battery for a certain amount of time. Again these are tricks used by several car manufactures, and the exact procedure will depend on you specific vehicle. If all else fails, contact our service department to schedule an appointment.

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
  1. Home
  2. Questions
  3. Lost temperature control on hvac

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: Auto climate control

Even without having specified what model Mercedes, yes they do use in car temperature sensors. Your issue can be related to the in-car temperature sensor or the climate control unit itself. Since Mercedes climate control systems are known for their...

Q: How much should my repairs cost?

Billing question sent to CS for the replacement of the positive battery cable, fuse, and repair to the engine harness on a 2008 Saturn Astra with a L4-1.8L engine.

Q: After a bout of wet weather, the climate control buttons in my car will not work.

Hey there. Blinking lights indicates there is a code stored. This is good news because it will help diagnose the problem. If all the lights blink, then the climate control unit will need to be put into self diagnostic mode....

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 Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...