74 (A/C Heater) Blower Switch:

[Norman S.]

The blower switch doesn't operate.
No power at switch.
Jumped from power to relay plug under hood and blower operates.
Previous owner had new heater core installed. Is it possible that somewhere there is a disconnected plug that can't be seen from the outside?
Would like some advice re the best systematic route to troubleshoot before dismantling the whole console.
Question: is the blower switch replaceable by itself or do I need a whole new heater control box?
(I've ordered a shop manual but it's not here yet.)
All advice appreciated.
Norm

[Harmon C.]

Re: 74 (A/C Heater) Blower Switch:

On AC cars their is a in line fuse that controls the highest blower speed on the fenderwell drivers side up to 1973's so 74 may still have the fuse. I would check the fuse block and fuse for power first. Then under the hood at the blower and the speed controls in the heater box under the hood.

[Norman S.]

Re: 74 (A/C Heater) Blower Switch:

Hi Lyle--
Checked out the fuses I can find. All OK.
Found a wiring diagram on line but both the non and a/c versions don't seem to list all the items.
For example, there is a "condenser" wired in near the heater box and a "relay?" on the firewall with a small black shaft coming out of it-- next to it says "START". After turning on the key and then moving the shaft, I can hear a click from inside the heater box but nothing else happens. The relay has the number 4175 stamped on it. The part number is 1243384 ESSEX.
I can get power from one terminal connection there but nowhere else (except the fuse on the driver's side.)
Question: Is the blower switch itself replaceable?
On the wiring diagram, it shows inside the car a "Compressor Switch", "Master Switch" and a "Blower Switch". Where are these located-- inside the console?
Thanks for your help.
Norm

[Jack H.]

Re: 74 (A/C Heater) Blower Switch:

Yes, heater & A/C controls are in the center console. You have two roll-wheel controls (one sets temp, the other controls mode) and a fan switch sitting above & between the roll-wheel controls.

When the mode roll-wheel goes to a A/C position, that turns the compressor ON. The heater fan switch controls the speed of the blower fan.

I'm surprised you can't find these details in your copy of the 1974 Chassis Service Manual....

[Bob H.]

Re: 74 (A/C Heater) Blower Switch:

Hi

It's sure easy to get sidetracked. Make sure you are not just using the high speed position. When in lower speeds it can be difficult to hear the fan run. I would try a lower speed and listen very carefully to make sure it is not running. I've just had several that were hard to hear and the high speed didn't work. Simple fix in that case is change the relay.

[Norman S.]

Re: 74 (A/C Heater) Blower Switch:

Yes, heater & A/C controls are in the center console. You have two roll-wheel controls (one sets temp, the other controls mode) and a fan switch sitting above & between the roll-wheel controls.

When the mode roll-wheel goes to a A/C position, that turns the compressor ON. The heater fan switch controls the speed of the blower fan.

I'm surprised you can't find these details in your copy of the 1974 Chassis Service Manual....

Thanks for the reply, Jack.
As I noted in my original post, my manual hasn't arrived yet so I'm kind of flying blind right now.
I know all the heater/ac stuff is in the console but I was looking for where the low and compressor switches were-- I've since found out and think one of these may be corroded or otherwise out which is why there is no power at the blower switch. (blower works OK)
Thanks for your help.
Norm

[Norman S.]

Re: 74 (A/C Heater) Blower Switch:

Good point, Bob. I wish that was the problem.
Have no power at blower switch. Think I've got it figured out now.
Thanks, Norm