911 Heater problems

RSQ911 · 02-10-2006, 05:03 PM

Hi everyone: I have a 84 Cabriolet with the manual heating system. The problem is the three speed center console control. It did "sort of" work (speed 2 only), now nothing. The blower motor at the engine works, the levers work, and the valves all work. So there is heat coming into the compartment. There are no blown fuses, and I switched out relays. But the three speed controller is not activating the footwell blowers. I have looked at the Bentley diagrams, but the info is more geared for the automatic system. I have tried switching the switch/console out for another one with no luck. Is it true that there might be inline fuses at the footwell blowers themselves? Help! And thanks!

tonythetarga · 02-10-2006, 05:12 PM

I don't think the 84 had fused footwell blowers unless the PO made the mod. They access to them is easy to check by unscrewing the covers. The footwell blowers are known for either squeeling like mad or quitting altogether. Check your feeds to the blowers. If you're getting power but they aren't coming on, it is time for new blowers.

sergeshishik · sergeshishik's Garage

My 84 has blower fuses located in the engine compartment. The fuses are on the exterior wall of the driver side behind a plastic door.

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imcarthur · imcarthur's Garage

RSQ911

See this thread Help! Does anyone understand the footwell blower circuit? This is a way to repair the heat controller which is probably your problem.

There are countless other posts on heat. Footwells were only fused from 87, but many have fuses added later because the fan motors tend to be a problem. If the footwells work when you run a 12v line directly to them, then it is the controller. See the fix above.

Ian

RSQ911 · 02-12-2006, 11:22 AM

Thanks for all your info and help! I will post the results and findings, so that it may be of use to someone else.

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Mysterytrain · 02-13-2006, 06:42 AM

I re-read your posting a couple of times to get a handle on your problem. Question remains..if you apply 12 volts to each of the footwell blowers do they work? Then the next thing to look at is the speed switch console..the 12 volts from the rear engine controller is fed to two of the microswitches in the speed switch console thru a black wire. It could be that the switches are bad. Notice that is a microswitch for each of the 3 speeds but they behave differently. Postions 1 and 2 route 12 volts thru two microswitches and up to the resistor pack. Position 3 routes a switched ground for the high speed 'AUX relay'. So you actually have two problems..one, getting the footwell blowers to operate at slow and medium speeds and the other to get the blowers to operate at high speed. That thread Ian suggested is the bomb for info on how the system works.

911Atlanta · 02-13-2006, 06:53 AM

Everyone above is right on. If you're not getting anything out of the blowers, either it's the fuses for the blowers (in the engine compartment) or both blowers are shot. They're notorious for wearing out, so don't rule out the blowers themselves. I had same problem and just replaced one and the other is squealing hard so it won't be long for that one either.

Good luck !

RSQ911 · 02-24-2006, 12:43 PM

Hi:

I put 12 volts to the footwell blowers, and they both work. Yes, slowly narrowing it down.

I switched out the center consoles, again, no change.

All fuses are good.

As I mentioned earlier, initially, speed position 2 worked.

How often do the speed control resistors go bad?

And, in testing the main relay in the engine compartment, do I bench test it, or in the car?

Thanks again everyone!
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84' Cab

RSQ911 · 02-24-2006, 12:49 PM

One quick note. In my owners manual (84 Carrera Cab), it shows that there is no relay in the trunk for the heating system. But there is one empty space, and one unused plug that is wired up.

Thanks!

nhromyak · nhromyak's Garage

Quote:

Originally posted by RSQ911

I put 12 volts to the footwell blowers, and they both work. Yes, slowly narrowing it down.

I switched out the center consoles, again, no change.

As I mentioned earlier, initially, speed position 2 worked.

...
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84' Cab

A 3 position Center Consoles (between the seats)? for the heater blowers in the footwells?

Or is this the center console for the fresh-air blower on the dash?

I am not clear on which switch is affecting your heater blowers that you are referring.

imcarthur · imcarthur's Garage

RSQ911

The relay we are talking about is on pg 971-3 in the Bentley - middle picture. This is the MAIN blower relay which is also necessary for the footwells. As well, as Mysterytrain pointed out, high speed also involves relay # 1 top picture.

You do have 2 red paddles don't you?

Ian

Mysterytrain · 05:22 AM

If you are digging into the 3 position switch that lives between the seats you can do some testing there. You can remove the console from between the seats by taking out the four mounting screws. Gently pry off the switch dial. Flip the unit over and you will see 3 screws that hold the switch assembly in place, remove them. Once you free the switch assembly you will have a good laugh at this tehnology. Mounted on that hunk of plastic are 3 micro switches [ made by Cherry on my console]. The first two are beefy enough to handle the current required for the low and medium speeds of the blowers.... they will have a black wire going to each of them and a white wire coming from one and a white and black from the other. If you have power [with the ignition in run] where the black wire is attached to the switches you can test each of those switches by triggering the levers with your finger and see if the voltage flows to the pole with the white and white/black wires attached. If there is no voltage on the black wire you need to trace that back and find out why. The third micro switch is a bit wimpy but it is left to do a wimpy job. Its function is to provide a switched ground for the solenoid on the infamous Aux relay that provides the high speed voltage. There are two wires connected to this switch one in Brown [ground] and the other is brown/blk, [switched ground]. You can test this switch for continuity buy flipping the lever to open and close it also check the ground connection by tracing back that brown wire yo where it is connected to the chassis. If all that stuff is working. Then you can button it all back up and look for the resistor pack and the high speed relay. The resistor pack is located in the trunk in the area behind the glove box. I'm not sure about the location of the aux relay maybe someone here can jump in. Testing the resistors again requires a meter. You can measure voltage coming in and going out..should be 12 volts in and less then that on each of the other terminals. You can also just measure the resistance. one should be .85 ohms and the other 2.3 ohms. You need to understand that the parts common to all of your issues are the microswitches under the red levers between the seats and the engine compartment controller. Those red levers switch on the controller..the controller then turns on the rear blower and the footwells..if nothing is working you might want to ck these guys out first. The microswitches get dirty, corroded or out of adjustment. With the ignition in the run position you can slowly lift the levers and listen for the relay [engine compartment controller] to click on.

imcarthur · imcarthur's Garage

btw Listen to mysterytrain. He is one of our heating gods.

Sorry to put you on a pedestal Ron, but you do have a great zen-like sense when it comes to this absurdly (& widely misunderstood) complex system.

Ian

Mysterytrain · 02-25-2006, 07:20 AM

LOL, Ian thats very kind..I guess? It comes from years of playing with electirc trains..I think the factory used Lionel Engineers for some of the electro-mechanical designs.

RSQ911 · 02-28-2006, 01:27 PM

Everyone, thank you all for your help!

Currently here is where the Cab is at.

All fuses are good, the heater valves all operate fine, the red levers operate fine, the blower motor at the engine works great, the main relay turns on with the red lever actuation, the footwell blower motors both work when an independent 12 volt source is applied, the 3 speed manual center console switch (between the seats) does nothing, a different replacement console with switch also does nothing, I have taken both apart and they are clean tight and do not appear to be fried.

But, there is no power coming to the footwell blowers.

Is there a way to test the resistor?

And, when testing power at the console switch connection, from the harness, does the switch have to be plugged into it, or not?

Thanks again!

Mysterytrain · 03:22 PM

Do you have 12 volts coming into the 3 speed switch? It should be on the black wire when the ignition is in the run position and the red levers are pulled up. I've re -colored that black wire in bold red so it will stand out in the drawing below. If you have 12 volts on pin 4 of the engine compartment controller then you should see 12 volts on pin 3 of the 3 speed switch connector. If you don't have 12 volts coming from the engine compartment controller then I would bet the controller is bad. I also outlined the switch in blue.

The second drawing is a flow diagram of the engine compartment controller. 12 volts is going into the controller on pins 8 and 3 [red lines in the drawing]. The voltage on pin 8 travels to the first relay [blue] where it waits to be sent to the rear blower. When the blue relay closes it sends voltage out thru pins 5 & 6 to the rear blower , it also sends voltage to the reed switch [yellow] and then to the footwell blower relay [orange]. Since you say the rear blower works..then the blue relay and all its logic circuits are fine.
I would ck the ground on pin 2...that needs to be intact to make that orange relay work. Then I would check to be sure that there was 12 volts on pin 3...if there is then I would look for it on pin 4 thats the wire connection that feeds the 3 speed switch and the blowers.

Couple of questions..is the rear blower new? is it a factory part? We got into a nice long thread about this because the rear blower has to operate in order for the footwell blower relay [orange] to turn on..that is done with the reed switch [yellow]

Mysterytrain · 02-28-2006, 06:45 PM

As long as we are examining the components of manual heat with footwell blowers I thought I would post some more pictures. The first photo below is the heart and soul of the 3 speed heater console..the switch assembly. This top view shows the 3 microswitches, the two grey switches for postions 1 & 2. The third switch [small, black] switches the ground for the Aux relay solenoid.

Close up of slow and medium speed switches:

The switch that controls the Aux relay for high fan speed:

The bottom view showing the connections for the light:

And finally the connector:

My question concerns the connector and the schematic posted above..one of these is incorrect! If you look at the picture of the connector and start with the grey wire with the blue stripe as number 1..that checks out ok on the schematic. Number 2 is brown, is also ok..#3 is black, again ok, # 4 ,white wire [slow speed] on the connector but the schematic states it should be the switched ground [brown/white], #5 is white/blk, thats ok and #6 is brown /white and from the schematic that's wrong. I think pins 4 and 6 on my connector or on the drawing are wrong. Can anyone help me sort this out? ..a little history, I bought the 3 speed heater switch console on ebay, new old stock..mint! I'm thinking this item might have been left on the shelf somewhere because when they tried to install it it didn't work correctly? I'm hoping its my connector and not the schematic because we have been using it a lot lately.

RSQ911 · 06:41 PM

Hi everyone:
Sorry for the very long delay (family crisis).
I have tried the "jumper wire" in the engine compartment controller, nothing has changed. The blower at the motor is factory and works fine.
Help!!!!!!!
Thanks,
Paul

Mysterytrain · 07-03-2006, 06:53 AM

Paul..do you have 12 volts at the 3 speed switch? The 12 volts going to the switch does two things..it provides the slow and medium speeds for the footwells and it also triggers the high speed relay for the footwell blowers.

RSQ911 · 07-06-2006, 11:54 AM

Hi Ron (and everyone else):
Happy belated 4th of July!

Here is what is new......... with the ignition on, the red levers up, the jumper wire added to the rear controller, the rear blower motor operating fine, there is 12 volts at pins 3 and 8, nothing at pin 4. Which means, no power to the 3 speed switch in the center console.

Again Help, and thanks!
Paul
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