64 Heater Control ?

[M W.]

Hi all,

I am having as bit of trouble with my heater control in my 64. The switch only works in the medium and high position with no low. I changed out the switch with a working original one I had but no luck. Any help here is greatly appreciated.

Thanks,
Craig Willetts

[John H.]

Re: 64 Heater Control ?

Assuming you've verified continuity through the switch positions, have you checked out the blower resistor? The "low" leg of the resistor may be open.

[M W.]

Re: 64 Heater Control ?

John, is there a easy way for the non-mechanically inclined to do this? I can only assume the switch positions work correctly. Further help is greatly appreciated.

Thanks,
Craig

[M W.]

Re: 64 Heater Control ?

Can anyone offer any assistance on how to check the heater control unit..low..medium..high ?

Thanks,
Craig

[Jack H.]

Re: 64 Heater Control ?

Pierce the insulation of the power wire to the blower motor with a pin. Connect a voltmeter between the 'pin' and ground so you're monitoring the drive voltage supplied to the heater motor.

Now, fire up the engine and get the charging system working. Once you've recovered from cold start current depletion of the battery (ammeter is stable at/near zero), run the heater fan at each of its speeds.

You ought to see the voltage supplied to the blower motor drop from full B+ (high speed) stepping down to lower voltages based on the resistor action of the blower motor speed control resistor network and the cockpit switch + heater relay.

If you get to low speed and you read NO voltage, you've got a circuit problem up-stream (the blower motor's speed control resistor network is defective, your wiring harness is defective, the switch/relay is defective)...

Now, knowing a certain fella out your way who SMOKED his dash harness playing with his cig lighter wiring, I think I'd suggest a competent auto electric shop for the diagnosis! Such shops are located in just about Everytown, USA because police cars are highly modified with unique electrical components and typically built/maintained locally.

So, if you don't know where there's a competent local auto electric shop, it's simple--ask a cop!

[Larry S.]

Re: 64 Heater Control ?

Craig, you may want to look at the posts on this subject that I initiated about 2-3 weeks ago; they may give you some help. Just look at my profile and search for posts by me (there aren't many). My problem turned out to be nothing but corroded connectors where the wiring harness connects to the heater blower resistor. You may want to be sure these connectors are absolutely clean and solid. I cleaned mine several times, thinking they were clean, but I only got a connection by plugging and unplugging them several times until I finally got "fire" (sorry; bad choice of words).