Blower Switch Melts

[leroge]

All speeds of my blower ( heat/cooling ) fan work fine...but after a while the blower switch on my dash gets hotter than hell. This happened last year to the extent that the heat 'melted' the switch control knob. I replaced the switch and the thing worked ok - no overheating. Recently, with the summer heat and need for air conditioning, the damn switch 'froze' on the high setting. That is, it physically would not move off the high setting. I removed it and took it apart to find that the internal metal contacts were destroyed. I then replaced the switch and the switch/fan seemed to go ok for a while, Very recently, with the onsite of temperature in Chicago, and with continued use of air conditioning, the switch started to get very hot again. I thought it might be the blower resistor. I removed it and it looks and appears to be working fine.

Any ideas????

[aleekat]

Usual culprit is motor drawing too much current. So either your motor is crapping out or the connections are poor from the motor/resister/switch. Seen bad factory crimp connections.

[leroge]

Aleekat...thanks for the response. Yes, that is my suspicion.....motor drawing too much current. The fan does blow at all five speeds and the resistors appear to be in good shape. As I said, this is now the second time I've changed the switch. I noticed the temp buildup on the switch 'pin' ( when I remove the knob ) to verrrrry hot earlier this summer when I had the air conditioning on for periods of time. However, there didn't seem to be a similar problem over the winter when I had the blower on for heat.

Do you have any idea how many amps that blower motor should be drawing at high speed? I am thinking about using a clamp ammeter to check the amps. If they are high then I suspect it is the blower motor.

Also, could there be some HVAC filter of sorts that could be making the blower motor work harder?

[Copytech99]

If, your connector pins got hot and toasted you may have poor connection (with resistance)and terminals are getting hot with higher currents. (I squared R losses)