Blower or Switch? and another AC question or two

[mdwilf]

I'm wondering if someone's experience can save a some time standing on my head with a voltmeter - my blower works on the two lower speeds, but not high - I assume this means I have a switch problem because it just sends different 'signals' to the fan for each speed?

Also, my truck is pretty much original w AC - on the pass fenderwell there is a little valve that appears it may have been a vacuum operated affair to shut off the water flowing to the heater core - is this original & are those of you with AC setups running this, or do you just rely on the doors in the heater box to stop the heat?

Thanks

[Longhorn Man]

your switch problem is more likely to be a bad relay, located on the heater box by the passenger kick panel up high. They commonly rust out and stop working.
The shut off valve you see on the fenderwell is original, but I can't help you on running with or without it... being I have never had working A/C in any of my trucks.

[Tom Vogel]

I had that problem more than once over the years with my 69 shortbed. It was always a bad switch. Just my experience.

[Ackattack]

I say relay

[leddzepp]

relay or switch....probably the relay.

You need the working heater valve or your A/C will not stay cold. It is an OEM piece. The heater core and evaporator core are right next to each other. This prevents the heater core from heating up.

[mrein3]

What I found when I converted to an AC controller is that the wire must have been a bit undersized from the fractory. ALL the switches and plastic plugs behind the switch that I saw used were melted.

Drop your controller down and remove the switch. Look at the plug. If it is melted just order one of each. If the wires are hosed you can fix those too. Go to Napa and tell them to give you a handfull of part number 725147. These are the female "Packard 56" or "Type 56" connectors. You can repair your wires with them, insert them into that new plug connector. Put the new connector on your new switch then look at the relay.

For the heater control valve under the hood, it cuts off the flow of coolant to the heater core when the AC is on. If you can't afford or find a new one just put a ball valve in there. Open it in the winter and close it in the summer. The factory style one which is re-popped is a better way to go.