My car's AC/heater won't work unless I'm driving on the highway at about 70 MPH.
Nov 12, 2022 at 8:53 AM
Heat/AC will not blow unless driving at highway speeds?
2007 NISSAN SENTRA
JESCAS872
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Hi,
Do you mean the blower motor doesn't run or it does, but you get no heat until driving at highway speeds?
If the blower motor is working, first, when the engine is cold, check to make sure the engine coolant is full.
If the fan doesn't work, start by checking fuses 10 and 11 in the interior fuse/junction box. In addition to checking the fuse condition, make sure there is power to and from them. The key will need to be on, and the blower motor requested on.
Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
If there is no power to the fuses, switch the blower motor relay with a different one in the same box having the same part number. If there isn't one, here is a link that explains how to test a relay.
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
Let me know what you find. I attached pics below showing power distribution and the fuse/relay locations.
Let me know what you find.
Take care,
Joe
See pics below.
Do you mean the blower motor doesn't run or it does, but you get no heat until driving at highway speeds?
If the blower motor is working, first, when the engine is cold, check to make sure the engine coolant is full.
If the fan doesn't work, start by checking fuses 10 and 11 in the interior fuse/junction box. In addition to checking the fuse condition, make sure there is power to and from them. The key will need to be on, and the blower motor requested on.
Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
If there is no power to the fuses, switch the blower motor relay with a different one in the same box having the same part number. If there isn't one, here is a link that explains how to test a relay.
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
Let me know what you find. I attached pics below showing power distribution and the fuse/relay locations.
Let me know what you find.
Take care,
Joe
See pics below.
Images (Click to enlarge)
Nov 12, 2022 at 10:07 PM
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