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Old 07-06-2007, 05:36 PM   #1
jfager
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99 Escort Is there a fuse for blower motor

Just wanted to try and see of there was a fuse for my heat / AC blower motor. I couldn't find one in any of the three fuse boxes in the car. I was wondering if it doubled with something else in this car, or if there wasn't a fuse for it at all. I want to try that first, before I get into anything bigger. My problem is that the blower won't come on at all. The AC compressor turns on but when I turn the fan switch it does nothing. The car just came out of the shop, and the mech says he didn't do anything that would cause the blower motor to stop working.
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Old 07-07-2007, 04:37 PM   #2
jamesmetairie
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Re: 99 Escort Is there a fuse for blower motor

sounds like my mechanic. fix 1 thing and break 2.
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Old 07-11-2007, 06:12 AM   #3
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Re: 99 Escort Is there a fuse for blower motor

Hi jfager, and welcome to the forum. Earlier Escort blower motors were unfused - they were instead fed via a 30amp circuit breaker - it fed the positive terminal of the blower motor, which was hot at all times. The negative terminal of the motor fed into a network of resistors to achieve the different motor speeds, and then there was a selector switch to select those resistors, and then finally to ground.

There's a diagram here for a '98 blower motor which differs slightly from previous years - chances are that your '99 circuit will be very similar, if not identical to that one. The blower motor relay is new, as is that feed taken from the 20A 'Wiper' fuse to energise the relay coil. The motor itself is still fed via a 30A circuit breaker but instead of being hot at all times it will now, because of that relay, only be hot when the ignition is at 'On' - the motor being fed via the relay's switched contacts. The thermal limiter within the resistor pack is also a new addition.

First check would be to see if your wipers still work. If they do then it's likely that the relay coil is receiving current and therefore the motor should have 12V at its positive terminal, so that would be my second check. If it has 12V then you have either a faulty motor (that would be unusual) or a break in the negative side of the circuit (much more likely) - that could be in the resistor pack, the selector switch, the interconnecting wiring or the final ground connection itself.

If you have 12V at the motor positive terminal then you can check the motor by connecting the negative terminal directly to ground with a length of wire and the motor should run as though switched to the Hi-speed setting. The ignition would need to be at the 'On' position to make that check (in order to energise the blower motor relay).

If the motor is good, then you would need to start tracing the power through the negative side of the circuit. It may seem a little counter-intuitive to be checking for 12V on the negative side of the circuit, but in the event of an open-circuit ground path, that whole lower side of the circuit would rise to 12V so that's what you're looking for. Everything above the open-circuit point would read 12V, and everything below it would read 0V.
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Old 07-14-2007, 07:14 PM   #4
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Re: 99 Escort Is there a fuse for blower motor

Thank you Selectron,

The wiring diagram that you posted a link to is exactly the same as mine. I have one question though. I have 12V going into the motor. That is good. The blue/black that comes out of the motor, however, only has about 3V or so. Is this indicating a problem with the blower motor. Also when I try to run a piece of wire from the blue/black wire down to a ground, nothing happens. To me it seems that this would be a bad blower motor. Do you agree?

Thank you,

Joe
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Old 07-14-2007, 10:46 PM   #5
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Re: 99 Escort Is there a fuse for blower motor

12V at the positive terminal is good, but under what circumstances are you measuring 3V at the blue/black wire? The voltage there will differ, depending on whether the blower speed selector switch is set to Lo - Mid-Lo - Mid-Hi or Hi. The best setting for testing purposes is to set it at Hi, and that gives you a zero-resistance path from the motor negative terminal to ground - if that path has no resistance then no voltage can be dropped across it (Ohm's law) and therefore you should measure 0V at the blue/black wire. If you still see a voltage at that point when on the 'Hi' switch setting then it means there is excessive resistance somewhere along the path from the blue/black wire to ground. That could be a bad connector (loose or corroded), or bad selector switch contacts, a faulty wire or a bad connection at the final grounding point.

Leaving that to one side though, the motor should have operated when you bypassed the ground side of the circuit with the length of wire. It still doesn't necessarily mean that the motor is faulty though. There is another possibility which I didn't cover in my first post, which is that you may have excessive resistance (bad connection, etc.) in the feed to the positive terminal of the motor. If that were the case, then when you give the motor a good ground connection with the bypass lead, current would flow in the circuit and a portion of the 12V supply voltage would be dropped across that resistance, with the remainder being available at the motor - and that remainder may simply not be enough to allow it to operate.

You can check that last scenario quite easily by connecting the bypass lead from the negative terminal to ground and then taking two voltage measurements. Voltage at the motor negative terminal should be 0V - anything higher than that indicates that you are not connecting the bypass lead to a good grounding point. The second measurement would be the voltage at the motor positive terminal (still with the bypass lead in circuit). That should be 12V - anything less than that indicates that you are dropping a voltage somewhere upstream of the motor positive terminal - dirty or pitted contacts within the relay would be prime suspect, or if not that then a bad connector.

Actually, I would go straight to that last test and make a diagnosis based on that. If you measure 0V on the negative terminal and 12V on the positive, then it would indicate a faulty motor but I still wouldn't replace it before I had tested it by removing it and connecting it directly to a 12V source. A heavy-duty bench charger should do the job, or connect it to the battery, preferably with an inline fuse in circuit - a 20A or 30A fuse should suffice.

Sorry to drone on, but although it's only a simple circuit, there are a lot of ways in which it could fail so it isn't possible to cover them all in a single paragraph. Let me know if you don't follow any of that.
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Old 07-26-2007, 07:23 PM   #6
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Similar problem that got worse

I had a similar problem. My blower motor quit working, but I had power to the blower motor. I figured it was the blower motor, and bought one online, replaced it.

Here is where it gets worse.

I just installed it and it worked. I decided to go for a drive. I put the ac on high and blower motor stopped working. Now I don't even have 12V on the wire that goes to the blower motor.

Where can I look next. Is it the relay (if so.. where is the relay)... a circut breaker or something. HELP.
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Old 07-26-2007, 09:12 PM   #7
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Re: 99 Escort Is there a fuse for blower motor

Hi djhuge and welcome to the forum. What year is the car? '95 and earlier didn't have a relay - the motor positive terminal was fed directly from a 30A circuit breaker. '97 and onwards have a relay between the 30A circuit breaker and the motor positive terminal. I'm not sure which arrangement was fitted to the '96 but I think it's the same as the '95, so no relay.

This is the relay location for the '97 Escorts:



If you don't have 12V at the motor, then check to see if you have it at the output side of the circuit breaker. I don't know which point fails exactly but there is at least one failure mode which leaves that path open-circuit, so you can have 12V leaving the breaker but not arriving at the motor.

The circuit breaker location changed slightly, depending on year:

'95 circuit breaker location:



'97 circuit breaker location:

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Old 07-28-2007, 05:09 PM   #8
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Re: 99 Escort Is there a fuse for blower motor

Thanks for a thorough answer, you're really a well of knowledge about the escorts.

However, the blower motor situation just got more silly and complicated -- this is for a 99 Escort.

I've noticed that occasionally,after not driving for a while, when I turn the ac on, the blower motor works on the low setting, but when I crank it up, it shuts off, and it won't work on low again. Sometimes it works on low for a while and then shut off.

When I check the voltage, it obviously gets the positive when it works, but when I crank it up, the voltage disappears. Now I know that when there are problems at different blower motor speeds, it usally means that it's a bad resistor - however, when you have a bad resistor in Fords (this was the case in my friends Focus).. then AC will work at high speeds, but not low.

Now it gets more silly. When I disconnect the positive from the blower motor and check the voltage, I get full 12V's when I turn on the fan on all speeds.

What the heck could it be? Is it the resistor? Blower motor (used replacement that works sometimes), relays? Circuit braker? Or maybe a larger problem with the electrical system (but if that was the case, i'd see symptoms in other places)...

any idea? Thanks in advance.
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Old 07-29-2007, 03:54 AM   #9
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Re: 99 Escort Is there a fuse for blower motor

I reckon the problem is in the 12V feed to the positive terminal of the motor. You could prove the point by running a temporary bypass lead from the output side of the circuit breaker to the motor positive terminal, and I think it would then work normally. That would bypass the relay, and the connecting wire to the motor positive terminal.

When the 12V goes missing at the motor, you could check back along the feed wires to see where you're losing it. I don't think the breaker is tripping, because you would hear it click, so I would check for voltage at relay terminal 87 (output) and terminal 30 (input). If it's still missing at the relay input then the only thing left to check would be the circuit breaker. To check the relay input voltage, unplug the relay and look on the relay base - you should see the terminal numbers marked on there - look for terminal 30 and then measure the voltage by probing into the corresponding socket for terminal 30 - you should have 12V. Actually, when the 12V goes missing it would be a good idea to head straight for relay terminal 30 and check it because that way you will divide the positive feed circuit roughly in half and you would then know which half to concentrate on.

I'm pretty sure that the negative side of the circuit is all ok - that's the motor negative terminal, through the resistor pack, through the switch and on down to ground - there's no indication of a problem there.

I know what you're saying about how it should work on the Hi setting even if the resistor pack is faulty, but that doesn't apply here because it isn't going to work at all if the 12V feed is missing, so that's not really relevant right now.

You said that when you disconnect the positive from the motor and check the voltage, provided the voltage is present, it will remain at 12V regardless of which speed setting you select at the switch - that's because the switch is no longer in circuit (nor the motor, nor the resistor pack) so that's the explanation for that one - it's to be expected that the voltage would remain at 12V regardless of switch setting so that isn't relevant.

If your 12V is there sometimes but missing sometimes then you won't have a clean break in the circuit - more likely it would be a bad (corroded) connector. The relay itself could also be faulty, of course - the switched contacts could be pitted or dirty, giving a bad contact not capable of reliably carrying the required current.

Just one last thing - to avoid misleading voltage readings, don't use any part of the heater circuit as a ground point for the meter negative lead. Instead, be sure to connect the lead to a good grounding point elsewhere - somewhere where you have a heavy bolt connecting to the car body, e.g. at the steering column or the seat mountings, etc. The reason for that is, that if you connect the meter negative lead to the motor negative terminal and the meter positive lead to the motor positive terminal and then fail to read 12V, well you wouldn't know if the problem was on the positive feed side of the circuit or the ground return side, so that's the reason for using an independent ground point. Just a detail, but an important one. Let me know if you have any questions.
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Old 07-29-2007, 06:47 AM   #10
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Re: 99 Escort Is there a fuse for blower motor

And this is the situation if you have indeed been measuring the voltage directly across the motor (i.e. meter negative lead to motor negative terminal, positive lead to positive terminal):

If you got a reading of 0V on the motor positive terminal, that would be inconclusive until you repeated the measurement with the meter negative lead connected to an independent ground point. If you then still had 0V then that would confirm that the 12V feed really is missing, so proceed as above and fault-find on the 12V feed path.

If on the other hand you then find that there is 12V there after all when measured from an independent ground, but still the motor isn't working, then check the voltage on the motor negative terminal - if that is also 12V then something has gone open-circuit in the ground path, so proceed thus: set the blower speed selector switch to Hi, and then trace the voltage through the negative side of the circuit - that's from the motor negative terminal, through the resistor pack, through the switch, to the final ground connection. Something along that path will be open-circuit, and all points above the open-circuit will read 12V while all points below it will read 0V. After locating and repairing the open-circuit, the motor should again work normally.
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Old 07-30-2007, 04:33 PM   #11
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Re: 99 Escort Is there a fuse for blower motor

Thanks for a great answer. I'll definitely check the voltage. According to the images in your last posts, the relays and circuit brakers are under the driver side dash.... you've gotta have a bendy and flexible back to do fixes in those areas....

ouch.

I'll let you know what I find.
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Old 01-12-2016, 08:41 PM   #12
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Re: 99 Escort Is there a fuse for blower motor

Ok so I checked terminal 30 in the relay box, and there is no voltage there. I went to the fuse box under the hood, where there is a 30 amp fuse named defog. I can only assume that this is the correct one. I don't know though. I can't find a circuit breaker at all. Am i even looking at the correct fuse? the diagram I am looking at says "blower 30amp" goes to terminal 30 in the relay box on a blue/orange wire. I see the blue/orange wire in the relay box, but can't find the other end of it. Any ideas?
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