We have a 2007 Mazda5 we recently purchased used from a Mazda dealer. We learned later that the car has had numerous repairs the dealer didn’t disclose, including a radiator fan replacement and possible new radiator. We noticed that the radiator fan was constantly running, even if the engine wasn’t but the key was in the “on” position. The fan shut off when the AC was turned on. We took it to our local dealer for diagnostics who said that wires had been crossed in the original repair, that they connected the wires so that the fan would always run and that we needed a new fan control module. We tried out a new module but it didn’t fix the problem, fan still runs all the time and is very loud. Husband thinks the fan might be blowing in the wrong direction: currently towards the radiator. Another problem, which may or may not be related, is that the AC only works well at high vehicle speeds. When traveling in town, the AC blows very mediocre cool and moist air. According to the original owner, they put in a new AC compressor and a new pressure switch and the AC apparently worked well. Anyone have any thoughts on these two issues?
If the fan motor is blowing air forwards then this needs to be corrected as that has an affect on engine cooling and A/C operation; especially at lower speeds.The motor is DC (direct current) and if it’s blowing backwards then the wire leads are reversed and need to be corrected.
There are a number of reasons why the fan could be running all of the time. Lacking a wiring schematic and trying to explain it to a non-mechanically minded car owner would be very difficult at best.
What this will boil down to is someone taking a schematic and sorting it out. This may take an hour or or it may take 10 hours. Electrical problems may be billed by the hour due to the unknowns.
How much of this the dealer knew about and did not disclose is also an unknown. Many dealers take cars in trade or auction purchases, detail them out, and then place them for sale on the lot.
This is why a pre-purchase inspection is important.
Even if the dealer had a hand in all of those prior repairs this does not mean the sales department knew about it as service and sales are their own little worlds…
Sure seems like a lot of problems for 2007 model car and if the dealer is the one crossing the wires and causing the fan to run in reverse then maybe you need to find someone else to sort it out as there really is no excuse for something like that.