blower motor issues

[pipe539]

Hi all, I have a 97 escort that the blower works kinda funny in hi speed setting the blower seems to barely blow but in second highest speed it blows harder any ideas on why its doing that is it a resister problem?
thanks

[Selectron]

If the three lower speeds work (even if they're slower than normal) then it's unlikely to be a problem with the resistor pack, but to help narrow things down a little would you say it's blowing normally on the three lower settings or are they also slower than normal?

[Davescort97]

Check the wire clip going to the motor. They tend to overheat and melt the insulation then cause the motor to perform poorly. If you are up to it, pull the fan and motor and check for leaves, debris etc. in the squirrel cage fan. I had the same problem you have and my fan was clogged with leaves and part of my owners manual that fell down there from the glove box. Your car doesn't have a cabin air filter.

[pipe539]

Thanks Guys I just bought this car on Monday it does seem that all the speeds are slower but I'm used to trucks this is my first car.

I will check the blower and the wire that goes to it.

[Selectron]

Below is the wiring diagram for the '97 blower motor. At the top of the diagram, a 30A circuit breaker feeds 12V to the Blower Motor Relay, and then to the positive terminal of the motor - a bad connection anywhere along that path could cause your problem.

The motor negative terminal then connects to the resistor pack at connector C287, and the outputs from the resistor pack plug into the Integrated Control Panel, which then plugs into the A/C Heater Control Assembly, which contains the blower speed switch. Finally, at the bottom of the diagram is the ground connection. The resistor pack will not be causing the problem, but a bad connection anywhere along that path could cause it.

There are several ways to pinpoint the problem. You could run a temporary 12V feed to the motor positive terminal and if that brings the speed back to normal then you would know that you have a problem at or above the motor positive terminal.

Or you could run a temporary lead from the motor negative terminal to a good ground point - that would cause the motor to run at full speed regardless of speed selector switch setting, and if it then runs at full speed then you know the problem would be at or below the motor negative terminal - between there and ground.

You could also find it by voltage measurements - with the speed selector switch set to 'Hi', all points between motor negative terminal and ground should read very close to 0V - if you get a reading higher than that, then it tells you that you have excessive resistance in circuit, probably caused by a bad connection.

Similarly, all points from the motor positive terminal upwards to the circuit breaker should read close to battery voltage, and anything less would indicate excessive resistance, probably caused by a bad connection or bad contacts within the circuit breaker or relay - further voltage measurements would allow you to pinpoint it precisely.

It's a simple enough circuit but there are a lot of potential failure points because there are so many connectors along the path, any of which could corrode, overheat, and fail, plus of course physical access is restricted and awkward.

You might want to check out the next-to-last post in this thread - it was for a '97 blower motor that had quit working (but in fact it would have been running slower and slower during the preceding weeks) - the owner traced the fault to a connector on the interior firewall which had corroded, overheated and melted. It would be worth seeing if you can locate it and check it out - a whole lot easier than tracing through the circuit with a multimeter.

'97 Heater Blower Motor wiring diagram