Hey everyone,

I’m chasing a front HVAC blower issue on my 1999 Discovery II.

The front blower does not work on any speed. The HVAC control panel powers on and appears to function normally, but the blower does absolutely nothing.

Here’s what I’ve tested so far:

• Original blower motor works when connected directly to the battery.
• Tried a new blower motor and it also did not run when plugged into the truck.
• Ground side appears to test good.
• Measured about 13V at the blower plug.
• Pulled the front blower resistor/control module. It had some corrosion, so I tried a replacement resistor/module, but it did not fix the issue.
• The resistor connector itself does not look melted or obviously damaged.

Since both blower motors work on direct battery power but not through the truck, I’m thinking the issue is somewhere in the power feed, connector, fusebox, or HVAC control circuit.

Has anyone run into this on a D2? Is there a common failure point that would show voltage at the blower plug but not carry enough current to run the motor?

Any guidance on next test points would be appreciated.

 

The blower has 12vdc at it all the time, the wire to the ground goes through the switch to a group of resistor coils then to ground. I have seen switches act p as the contacts in the switch get corroded. Usually high works if the coil pack is bad, but it could be a bad coil pack. Resistor coil pack should be down by the blower motor. If it checks out, then go for the fan switch. sometimes sliding the switch back and forth can make it work but it would need replacing or cleaning, inside. The fan switch for the rear a/c is the same switch and used ones from there can be in better shape.

 

I had a similar issue about 10 years ago. I removed the blower and put 12V direct to the blower. The blower worked. So, I started trial and error and got lucky. Cleaning the corroded contacts on one or both of these relays solved the problem.

 

Quick update, I cleaned the relay contacts/sockets and reinstalled them, but unfortunately no change.

A few more details:

• I can hear a relay click when commanding the blower on.
• The EATC display works normally and the fan bars increase/decrease as expected.
• Both the original blower motor and a replacement blower motor work when powered directly.
• Replacement blower control module/resistor did not change anything.
• The 13V I measured at the blower plug was with the blower unplugged, so I’m going to re-test it plugged in/back-probed under load.

At this point I’m thinking the next step is confirming whether voltage collapses once the motor is connected. If it does, I’ll start tracing back through the relay/socket/feed side.

Appreciate the help so far. This one is turning into a classic D2 electrical rabbit hole.

 

Just to say it, did you try that EATC self check process? I've never seen it do anything useful on any truck, but you could be the first!