C2 HEATER CONTROL VALVE (1967 L79/AC)

[Jimmy B.]

Ok, I need help/advice here. I just got my car shipped from the "S.F. Bay area, through the Gulf of Mexico, Panama Canal, a port stop in Holland, and finally to a U.K. port for final delivery) I took delivery last Monday. The car has been in storage since 1979. Upon heater activation I get nice "cool" air. I suspect the heater control valve (the car has a new heater core, hoses, DeWitt radiator, & waterpump) When I feel the heater hoses to the valve they feel warm. I have A/C which actually appears to work fine but no heat. Can someone walk me through/suggest how to activate the control valve. I unplugged what appears to be a vacuum line on top of this valve and felt no vacuum while the engine was running, what gives? Where does this line get the vacuum from? H E L P? Thanks for your help.
Jim Blakely
p.s. I also need a used clock wire loom (my pigtail for this was cut off)

[Ed Jennings]

Re: C2 HEATER CONTROL VALVE (1967 L79/AC)

There is a vacuum switch behind the glove box that supplies vacuum to the valve.

[Geoff C.]

63-67 AC Vacuum Switch Repair

Sir,

If that air condition vacuum switch is adjusted properly, but merely leaking you can fix it for less than a buck, or rather British pound. This repair could save you the equivalent of $50 US and many headaches since you are on a different continent.

Disconnect the battery and then remove the glove box lamp. Pull the orange colored hot lead from the glove box lamp switch and then the entire glove box assembly can be removed with a Phillips screwdriver. This allow direct access to that Brass AC vacuum switch for adjustment or repair. Those Brass switches really are quite durable and will out last all of us. All one ever needs to do is replace the rubber seal inside with an O-ring and lubricate with typical vacuum grease. Switch adjustment is covered in the Assembly Instruction Manual.

The 1967 air conditioning vacuum circuit and components are quite simple and their connection and routing can be seen by clicking on the Climate Control Hose link. My 67 AC blew 38 degrees at the dash vents this past June when it was 95 as measured by a Blue Point IR digital thermometer with this repaired switch. (But you will also need to convert those to Metric also.) Quite honestly I have not used the heat mode very often, as I do not drive this car in the winter however it does not leak hot air into the cockpit when the AC is off either.

Geoffrey Coenen




Save $50 Bucks

[Ronnie Robertson # 36786]

Heater Operation

Jim,
For A/c cars, there is a control switch located on the heater box behind the glove box. When you pull the heater control on the dash for heat, it mechanically trips this switch to allow vacuum to flow to the control valve in the heater hose opening it and allowing heated water to flow into the heater core. Vacuum to this switch comes from a hose attached to the fitting on the intake manifold (just behind the carberator). The hose passes across the firewall and into the dash area thru the large round rubber grommet that the oil pressure line also uses. You can use the AIM for details. E-mail me if this doesn't help.

[Jimmy B.]

Re: 63-67 AC Vacuum Switch Repair

Geoff,

Thanks for your 2 cents worth, I was just looking at your schematic/catalog online. It looks like I've got some great advice here on-line and now I will pursue trying to get my heater working.

Jim Blakely

[Jimmy B.]

Re: Heater Operation

Ronnie, Thanks for the information, I'll be tearing into this later in the week. This poor car has been sitting since 1979 so I think lots of parts need gentle persuasion (and lubing). Jim Blakely

[Jimmy B.]

Re: C2 HEATER CONTROL VALVE (1967 L79/AC)

Ed, Thanks for the information. I am taking out the glove box door later this week. Jim

[Wayne W.]

Re: C2 HEATER CONTROL YEA, BUT

I think that it defaults to heat if the vacuum is cut off or lost. So it should be working if you have no vacuum.

[Randy S.]

Re: Heater Operation

And it's my understanding this vacuum switch has a designed "vacuum bleed" which allows the vacuum to bleed off after heater is turned off. This "bleed" is actually a small vacuum leak when heater is in off mode.

[john pickens]

Re: Heater Operation

Something else to check. I had the same problem until I realized that someone had placed control valves in the input and output hoses to the heater core, mainly to shut off flow in the summer to keep the interior cooler. Open these and voila! plenty of heat. Worth a careful look.