I’m having a bit of an issue with getting the heater blower to work...

The motor bench tests fine

The wire on the heater control lever is connected correctly

When I pull the lever back, I can hear the relay clicking in the engine bay

However, when I connect the fan to the heater wire the motor does not run. I confirmed that brown connected to brown and green to yellow, just like the picture below.

I was holding the motor - so it wasn’t separately grounded - would that be the issue?

Any ideas ?



Click to view attachment

Maybe the relay contacts are bad?

A clicking relay doesn't mean any current is flowing through the relay. Can you try another?

The tunnel warm air lever may be compromised. The contact 'nub' that powers the fan when the lever is pulled up fully may not be making proper contact. Does the fan spin up to speed when powered independently?

If that was the issue, the relay wouldn't click, no?

Try another relay.

No luck with a new relay that I know is good

This ...

He said the fan "bench tests fine". I ASS-U-ME he means fan on bench with power and ground applied=fan works.

Brown to fan is ground (from the ground point above the relay board, I believe). Make sure there is a GOOD ground.

Green to fan comes from the heater fan relay. It should have battery voltage with the fan relay closed.

The control side of the relay (the coil) is grounded by the fan lever switch. I believe this is good because the relay is heard clicking.

The 25A fuse on the relay board supplies battery voltage to the relay (input, if you will), and when the relay contacts close, the green wire is energized.

If you hear the relay click, and you do not have power at the green wire on the fan, the fuse is bad, the relay board is bad, OR the relay is bad.

Do you have battery power at the green wire to the fan? And does the fan have a good ground?

BTW, a voltmeter is better than a test light. An old test light can operate on as little as 3V, so the circuit could look OK, but not be able to run whatever load is on it.

You assumed right. But no power at the fan. So I’ll check the fuse and wire. Thanks guys

also make sue that the green jumper wire is installed under the cover of the rear bulkhead replay board plug

Pretty simple circuit to troubleshoot. Lever pulled all the way up, connects relay to ground. Should be 12 volts at relay. Using a digital volt meter or analog meter, check for power and ground at the blower.