Q: Heater and ac both not working is there anything that could cause both to go out or is it 2 seperate issues?

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The heater and ac both do not work and went out around the same time. My ac hasnt worked all summer and as the weather is now getting colder i have noticed the heat isnt working either. I know how to diagnose each on their own but before i dive in wanted to know if there was anything i am not thinking of that can cause both issues. The fan kicks on low to high the design makes it difficult to be able to tell if it is switching between cool to heat so that is the only thing im not 100% confident in but it does seem like its cooler air when on ac mode.

My car has 142000 miles.
My car has an automatic transmission.

The only components in common are the blower system (motor, switch, resistor block, etc.), the heater control valve (must be working to switch between heating and cooling) and the in-dash ventilation network "doors" (again, those "doors" must be working to switch between heating and cooling). All other components are "unique". Based on your description, I cannot pinpoint the likeliest fault (there are many, many possibilities, some simple and straightforward, others more involved). Consequently, the most efficient thing to do is just request an A/C diagnostic/inspection and the responding certified mechanic will look at the entire HVAC system and let you know exactly what is required to restore the system to proper function. Just indicate in the "notes" that both the heating and cooling functions are not working properly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.

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