this ones for you tech guys.......69

[autodynamics]

on my heater ac diagram the schematic shows that off the heater control switch (vacuum) there are 5 electrical connections which all go to a molex plug, of which c2a-18dbl and ca4-16br g to a time control relay.... my question is this where is this relay located and what does it do......on a side note while testing for my output wire (blue)for my a/c i noticed that there is power on the blue regardless of where the heater a/c switch is in whether heater def or max ac is on....i understand def will turn on the a/c but heat? do i have a bad a/c vacuum switch or does this time delay relay have something to do with it....also keep in mind my car is not running now will be next week and maybe this has something to do with it.. thanks Pete

[Nacho-RT74]

blue wire should get power just on AC and MAX AC

[Corellian Corvette]

Really? I have mine hooked up per the manual and I get A/C on everything, including heat. I was told that's the way it's supposed to work (it keeps the air drier inside the car)

The delay - I believe - connects to a sensor underneath the heater box (on the inside) to prevent the A/C from coming on under a certain condition (which of course I can't remember now)

[Nacho-RT74]

Dunno, because 3rd gens doesn't carry delays or any sensors around. In fact donno what really does the delay. I think shuts off and on the compressor clutch according with temp inside cab.

Yes blue gets power just on Max AC and AC. The prong below the blue wire on control switch ( I think remember is green traced ) is the input from fuseblock to clutch

Black wire is batt input to blower.

Tan low speed, light green is medium, dark green is fast speed ( direct without go to resistor ) Heater speed ( diff than the rest ) is brown.

If you see dark green going to resistor is because is the resistor output what is spliced on to the direct fast speed to feed the blower through one only wire.

[autodynamics]

ok here is the answer..... the time control relay is located on the bottom side of the heater box (passenger side)
the blue wire get energized on all settings except heat in which it turns off. so the blue wire is the output wire to the a/c system....thanks for your help

[Corellian Corvette]

Cool! That's what I thought - so Max AC, AC and Defrost all have the AC engaged.

The "heat" setting (when heat comes through the floor) is not engaged. Is this what you mean?

[Nacho-RT74]

ok, SORRY but I have to reafirm AGAIN blue wire ONLY HAS TO HAVE Power on max AC and AC.

AC system does have 4 speeds actually

-heater
-low
-mid
-high

After analize the circuit and read a recently bumped thread about, the time delay powers that blue wire when heater function gets the power THROUGHT the blower heater speed ( brown wire ). Then when delay will cut the power to Clutch.

HEATER doesn't response the blower speed, has its own speed ( thats how the delay gets the power to feed the clucth ) and is differently routed than the lever switch. DEF could not get the power to clutch through some blower speed due DEF does have blower speeds.

[Corellian Corvette]

Ok there may be some confusion. Pulled my 68 Service manual out. Here's what it says. I'm assuming 69 is the same.

24-2 AIR CONDITIONING

Fan Switch - Permits the slection of low, medium, or high blower speeds - used when operating either the heater or air conditioner.

Not sure where there are 4 speeds Nacho. Can you clarify what you mean?

ELECTRICAL CONTROLS AND CIRCUITS
Push Buton Control
The compressor clutch circuit is energized when either the "MAX - A/C" (maxium air conditioning) or the "A/C" (fresh air-air conditioning) push buttons are depressed. The "OFF" button turns off the system.

OK got that. HOWEVER, later is says the following.

Time Delay Relay (Coronet and Charger)

A Vacuum actuated time delay relay is located on the bottom of the fresh/recirculating air door housing. The purpose of this relay is to reduce the interior windshield condensation to an acceptable level.
When the ambient temperature is above 25 degrees, and the heat or defrost buttons are pressed, the air conditioner will go on for a period of 1 to 1-1/2 minutes.
If the system is shut down for less than 10 minutes no delay will occur upon restarting. The relay will reset automatically after ten minutes shut down.

---------
So this would explain (sort of) why my heater and defroster are causing the clutch to engage and the compressor to come on.

What I don't understand, and I could not find, is how to test if the relay is working. I haven't let the car run with the Heater on for over a minute yet (in test mode) to see if it's coming off. I believe in the case of my car the clutch is staying active. So I need to test for this.

[Nacho-RT74]

Put Heater, function and try to fit a diff blower speed ( low, mid and high ) and you'll notice speed won't change. Heater sets its own speed directly to speeds resistance out of the blower lever switch- Note how does run the Brown wire directly to resistor block

That is at least on 3rd gens, but wiring and resistance  from 2nd to 3rd speed doesn't change. Only change between 2nd and 3rd gen is 3rd gens have a VENT function, what earliers don't