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I want to run current through the heater blower. So do I just connect jumper cables to the car battery and connect those to the heater blower inputs? Can I leave the car positive and negative battery connectors connected to the battery, while connect the jumper cables to the motor?

 

I'd just take the blower motor apart. Since you know there is 12v going to it, there is no more need to re-create a test scenario with jumper cables.

 

But just for arguments sake, what if I did want to. Cuz I'm also trying to fix my not working fresh air blower. And that connector has no voltage, so I want to test that motor as well

 

Marlon, this isn't rocket science, but you strike me as one with minimal to little mechanical experience. Is there someone you know who can work with you on this, and tutor you a bit? You may want to get a book on automotive electrical and get some basic knowledge before you go too far in testing stuff. Armed with some basics, and using powers of deduction, with the proper manuals is a basic foundation for automotive repair. I'm not trying to be critical of you here.

 

Good advice. Yeah, I know someone who is proficient in car mechanics/electronics. I'll hook up with him, before I electrocute myself

Marlon

 

Ok, my fresh air blower motor is also toast. Took out the fresh air blower after getting 12v reads coming out the plug ( for all three fresh air settings I, II and III).

The motor looks melted. It's def a goner. That makes the heater and fresh air motors being busted. On top of that the connector on the auto heat rod is broken too. I now hope my footwell blower motors are not toast as well. We'll see once I replaced the heater motor if they work.

Marlon

 

You can inspect the blower motor to be sure. I don't think there is a lot to gain by rebuilding them. Just buy the cheapest new replacement you can find.

 

My Porsche guy has some replacement motors lying around. I'll just get those. Then I have to replace the auto heat rods connectors. And when I turn on the heat, hope it all comes alive

 

Now that you know why you are not getting forced heat into the cockpit, make sure you first determine why the plastic socket broke. It's most likely because the plastic sockets are 23 years old, but installing new sockets on the ends of the servomotor rod will not solve the problem IF the heat exchanger dampers are rusted closed. Get under the car and make sure they are free moving. Clean and lubricate directly on the damper butterfly valves especially the center pivot pins. Cleaning and lubricating these butterfly valves will make it easier on the new plastic sockets and 23 year old servomotor. Who knows, perhaps this will extend the life another 23 years.

 

1987 911, 3.2 with "manual heater controls" no servo. Heat discussion

The engine blower works 100% of the time when I pull either red handle

Sometimes the left/right footwell blowers go on. They both either work, or both don't work. When they work, I can select left/right and works as one would expect. When they don't work <duh> they don't work.

I can't seem to find a pattern as to when they do /don't work.
Fuses: not an issue, because they both work or both don't work.
Guessing resistor bank, not an issue, because when they work, all 3 settings work.
Checked the rear fuses: 25am to the engine blower (which has always worked, although the fuse looked awfully thin/brown, replaced it anyway.)
Looks like a 16 amp fuse, on the bottom that goes to the foot wells, or maybe they go to the blower.

(PS 3 fuses back there, and with ignition off, all 3 had 12 volts on them. Meaning that the switching must happen somewhere else. Didn't expect to see that, but what do I know.

Having looked at the Bentley, seen the PET, know how to use a VOM, what is lacking is a general description of how they "should" work, manually.

My problem: the interior side blowers sometime work, sometimes not.

So, what would help, for my manuall controlled heat/blowers
What controls the engine blower? Ignition on, either lever must be up, and maybe it drives a relay or not. Is this the rear relay? Switches 25 amp to the engine blower?

What controls the left/right inside blowers.
Ignition on, associated lever up, now down, the enginer blower must be on, and perhaps that relay controls "something". Sure there is a fuse before the blower, but I'm looking for a logical description of what is involved in a motor coming on.

Thanks. kz
1987 911 carerra convertible 3.2

 

There is no pattern, because it is most likely the blowers themselves. It is well-published that they wear over time, and often the fan drags in the housing. Usually, they can be re-habbed with disassembly. A search should find you some basics on this.

 

The blowers aren't all that old, call it 5 years. As I said, they work strong for days/weeks, and then suddenly stop. I'm thinking electrical, but not that they need to be rebuilt. They are smooth and quiet when they do work. I did find some "great" articles and simplified explanations on pelican parts forums by searching for footwell blowers. (simplified explanations; simplified drawings, plus the usual PET drawing. Have yet to see if I have power to the front relay, one step at a time.)

I measured the voltage in the engine compartment to the three hot all the time fuses. I was surprised that they were a full 12 volts at any time (as they should be) but to get a good reading, I couldn't use the aluminum controller case as a good ground. Voltage varies 7-12 volts. Yet, when I put my VOM onto the engine block, a solid 12 volts. I'm thinking it is a grounding issue, so to be sure, which doesn't signal my front blower relay (under the bonnet) to engage. That is my guess. I'm going to check the grounds in the rear compartment, and to be sure, will add a grounding wire directly to the aluminum chassis to a solid engine ground. I will report my results.

Funny, after working in the engine compartment, checking he fuses, the front blowers came on. Didn't touch anything, power cycled the car, and they wouldn't work. Figured I'd "jiggle" the fuses like before, and no joy. After putting my tools away, got into the car and they are running. Smartly, I didn't touch anything, and they have been working for 2 days. Go figure. Not the blowers, but something else.

My thought: if I have power to the front blower relay, when the rear fan is running, I have a front relay problem.
If I have no power o the front relay, when the rear fan is running, I have a blower controller issue, perhaps worked out by jumpering the reed switch. Don't think it that, but have nothing yet to rule it out.

Seems almost no one has a simplified diagram with mechanical heat control. But had enough descriptions that I feel armed to dig into the next level.

dw

 

Well, your further description certainly seems to point to electrical. I also didn't see your both on or off, before.

 

If you have checked the blowers by jumpering 12v to them and they work, and there is power to the blower relay, then I would suspect the blower relay. It's the silver box in the engine compartment (see Bentley Service Manual). You can verify this by prying off the relay cover and manually closing the relay contacts. Relay contacts sometimes stick. You might be able to file them clean and save the relay, since it is very very expensive. Unfortunately, this is a not 100% fix, just a band-aid. The real fix would be a new relay, but you definitely want to isolate it first before buying a new one.

 

I'm late to the thread, but found some great stuff here to help go through my heating... ended up being a combo of 'heating control relay' problems in back and shot motors up front....

http://members.rennlist.com/imcarthur/911autoheat.htm