Car Doctor Q&A: With Electrical Stuff, Check the Basics First!

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Whenever you’re diagnosing an electrical problem, there’s a sequence to follow that can save you a lot of time, effort and money.

Q. I have a 12 year old Honda CR-V and the radiator fans were not working. I went to a junk yard and got both fans and now the fan for the air conditioner is working OK, but the regular fan doesn’t work.

I put power to the fan and it did turn on so I know the fan is OK. There were a couple of relays that I swapped out and still the fan doesn’t come on. I’m at a bit of a loss, there aren’t any computer codes and the temperature gauge seems to read correctly. Before I replace any more parts do you have any ideas?

A. You never did state if you checked all of the fuses. Just because the fan for the air conditioner turns on, that doesn’t mean there is power to the other fan. To often technicians and DIY’ers jump to conclusions without checking the basics first.

Pulling up a wiring diagram on the technical data base that I use (Alldata) and guessing that your CR-V is a 2005/2006 model there are a couple of fuses to check. There is one fuse for the A/C fan and fuse number 4 for the cooling fan. If this fuse is bad it most likely failed because the cooling fan was drawing too much amperage.

There’s also a temperature switch that tells the fan to come on. You can check it quickly by unplugging it and jumping the terminals in the plug. When you turn the key on, the fan should come on. If it does, the issue could be your temperature switch.

Here’s a video showing you how to do it:

John Paul is senior manager of public affairs for AAA Northeast. A certified mechanic, Paul tests dozens of new cars each year and also hosts a radio show on AM 950