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Has anyone ever tried to add a secondary blower fan? Pages: 12

ScotY on Fri September 11, 2009 2:33 AM User is offlineView users profile

Another question about my old Suzuki Samurai...the air flowing out of the vents is pretty cold, there's just not a lot of it. This is a 21 year old vehicle but I've totally removed all the ventilation components under the dash, cleaned everything up, etc. I can't think that there's anything wrong with it. I have thought about replacing the blower motor but I'm not hopeful that that will make a significant difference. The way the system is designed, the blower sucks air through the evaporator. I don't know if this is the "normal" way it's done...this is an old and odd little truck. Anyway, there's a roughly 6/1-2" x 6-1/2" area on the inlet to the evaporator where I might be able to add a supplementary fan. Anyone think this will work? If so, any leads on where I might find a suitable fan?

Thanks, Scot

iceman2555 on Fri September 11, 2009 10:24 AM User is offlineView users profile

Why not first insure that the system (blower/controls) are operating as spec'd. Test system voltage/amp draws to determine if the blower is indeed functioning as it should.
Also, with a vehicle this old, it is possible that the air plenum area has developed 'leaks' that are 'robbing' vent air speed.


-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

ScotY on Fri September 11, 2009 5:31 PM User is offlineView users profile

Hi iceman,

Thanks for the suggestions. I took the entire ventilation system apart, cleaned it, and put in new sealing tape. It's as close to "like new" as possible. I have a brand new Optima deep cycle battery so that's not the issue. The alternator is a really small and weak unit though. With the a/c on and the blower on high, the engine needs to be about 2500 rpm or greater to maintain voltage, i.e. below 2500 rpm the battery is likely being depleted. I did not check the health of the blower motor as I don't know what to look for. I can measure voltage and current usage but don't know what the specs should be. Any idea on that?

mk378 on Sat September 12, 2009 8:08 AM User is offline

Measure between the terminals at the motor, make sure that nearly full battery voltage is reaching the motor with the switch on high. The switches often get burnt up and fail to deliver full voltage. There have been cases on other cars where aftermarket replacement motors and fans had inferior performance. Some even rotated backwards. Note that a squirrel-cage blower rotating backwards will still blow air "forwards," but at greatly reduced volume.

ScotY on Sat September 12, 2009 10:32 AM User is offlineView users profile

Thanks, that's really good info that I will try. Is there any way to determine the actual health of the blower motor without buying a new one for comparison?

NickD on Sat September 12, 2009 11:08 AM User is offline

Typically these so-called imports draw 16 amperes at full load. Nothing like having the blower motor assembly on your work bench for performance tests. Can also remove the grille under the windshield to see how much trash has accumulated in there.

graeme on Sat September 12, 2009 10:35 PM User is offline

An easy way to check the load produced by the blower is to just measure the voltage drop across the battery when you have it on high speed and the enigine not running. Compare this with a known electrical load such as your headlights which should be ~10A on low beam. The voltage loss running the blower should be ~1.6 times that of your headlamps.

True you could have a dodgy switch would show a reduced reading, but on high speed your fan should be switching through a relay, which dont typically suffer in this regard.

ScotY on Sat September 12, 2009 11:27 PM User is offlineView users profile

Thanks guy, great info! I'll sort through this and check the old motor and see if I can't determine if it's bad. I did find 6.5"
fans, they would fit perfectly onto the inlet of the evaporator core. I'm guessing it will be really noisy though. The fan looks just like the type for condensors, just smaller.

bohica2xo on Sun September 13, 2009 12:49 PM User is offline

Scott:

That is some terrible advice. There is no linear relationship between battery voltage & load, especially when you are measuring small percentages of a battery's capability.

There is no relay in the '88 Samurai HVAC system The heater control is fused @ 15 amps, indicating that the fan circuit draws somewhat less than that. The fan is 3 speeds, through a power resistor.

Given your tropical location & the age of the vehicle, you should check all of the connections for corrosion. The Blue wire at the fan motor / resistor is the high speed (full voltage) connection. With the vehicle running, and the cabin fan on the high speed setting you should check the voltage at this connection. If it is more than one volt below actual battery voltage measured at the battery posts you have some resistance in the circuit.

You could also test the fan motor by feeding it directly at the blue wire from the battery with a 12 gauge wire. If the fan speed increases noticably, you could install a relay for high speed.

Remember to check the ground connections as well. Grounds corrode, get loose etc.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

NickD on Sun September 13, 2009 7:40 PM User is offline

Is it one of these?



Be interesting to see a circuit diagram of the AC circuit, if that 15 amp circuit powers both the clutch coil and the blower, can't be much of a blower, fuse at approximately twice the size of the normal load due to motor surge currents. That leaves about 5 amps for the blower. Was this always a problem with poor air flow? Or was it good once then kind of died out?

ScotY on Sun September 13, 2009 10:55 PM User is offlineView users profile

Thanks for the advice, bohica. I'll do some poking around and see what I can come up with. Two more work days before I get a day off to work on the little Samurai.

Nick,
Yes, that's a Samurai but mine is what they call a tintop, there are convertibles, convertibles with a fiberglass hard top also. I'll see if I can't find an a/c wiring diagram. It's an '88 but I've only owned it for a few years so I can't say if the fan ever worked any better when it was new. I bought this thing because the first vehicle I ever owned was a Samurai that I bought new in '86-87. I sold it after owning it for a few years. They're pretty rare nowadays, at least around here. I wanted one again to sort of relive my younger days and to teach myself how to repair stuff.

Edited: Sun September 13, 2009 at 10:59 PM by ScotY

ScotY on Sun September 13, 2009 11:17 PM User is offlineView users profile

Here's an a/c diagram I found. It might be missing the other half so I'm still looking for another one.


Here's my tintop...it's a work in progress but it's getting there. The body work and dealing with the rust was no fun.

mk378 on Sun September 13, 2009 11:47 PM User is offline

According to the diagram, the condenser fan and compressor clutch are powered through the 20A fuse shown near the relays. The 15A fuse powers only the evaporator fan, idle up valve, A/C amplifier, and relay coils. The last 3 should be well under 1 amp total.

ScotY on Mon September 14, 2009 2:38 AM User is offlineView users profile

I'm sorry, I wasn't thinking. My a/c is an aftermarket unit from AMA so the only thing (I assume) that is powered through the switch is the blower motor.

NickD on Mon September 14, 2009 8:51 AM User is offline

Your blower mounting plate is a key component and you say you are using a bladed fan? I don't know without looking, perhaps just the motor and a squirrel cage blower wheel will fit with some modification. Wiring and fuse sizes can be changed, can even wind your own nichrome resistors.

See there are boards on the net dealing with the Suzuki Samurai, perhaps talking to other owners may shed some light. Did join a Supra club like thing, most of the guys on there didn't even know how to change a tire, so got bored and left it, you may be lucky.

ScotY on Mon September 14, 2009 11:17 AM User is offlineView users profile

I'm just using the OEM blower motor/squirrel cage at this time. My original question had to do with adding another fan to blow air into the evaporator housing to supplement the original blower. Lots of good tips were given to me so now I can (hopefully) determine the condition of the stock blower and go from there.

TRB on Mon September 14, 2009 11:43 AM User is offlineView users profile

Quote
Originally posted by: ScotY
I'm sorry, I wasn't thinking. My a/c is an aftermarket unit from AMA so the only thing (I assume) that is powered through the switch is the blower motor.

With this kit you use the OEM blower motor and fan switch.



-------------------------
When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

graeme on Tue September 15, 2009 6:25 AM User is offline

Quote
Originally posted by: bohica2xo
Scott:



That is some terrible advice. There is no linear relationship between battery voltage & load, especially when you are measuring small percentages of a battery's capability.


Really, it has worked pretty well in my observations with loads from 5-50A on car batteries where Ive measure the currents. Surely if the voltage drop was more than the headlights this would indicate the fan is pulling at least more than the headlights? which is about all that needs to be determined here.
terrible advice? hardly.

I agree, the internal resistance of a car battery is never going to be a fixed value due to the nature of the chemical reactions going on, but would you like to tell us how wrong it could be and back it up with some data? suspect not.



bohica2xo on Tue September 15, 2009 12:46 PM User is offline

Graeme

1) Your assumptions ignore Ohm's Law.

2) Your assumptions ignore Peukert's Law

3) Your assertions were that the so called measurement would be linear.

4) Without knowing anything about the blower you claim it would draw much more than the headlamps.


Your assertion that the blower should have a voltage drop of 1.6x the headlamps is wrong. The blower in this case is only fused @ 15a, and draws less than that.

A 230 cca battery is rated to provide 230 amps @ 0F, while maintaining a voltage above 7.2v Extrapolating that data to your alleged linear model suggests a voltage drop of .0239 volts per amp of load. So a 10 amp load would represent a .239v drop from 12.7v, for a voltage of 12.461v Your factor of 1.6x voltage drop would be .3824, showing a drop to 12.317 volts.

Sounds great on paper. But a battery is not linear. I took that exact battery to the bench, and loaded it with 10 ohm 25w resistors:

Open circuit battery voltage 12.69v

With 1 10 ohm load 12.42v 1.24 amps

with 2 10 ohm load 12.32v 2.464 amps

with 3 10 ohm load 12.22v 3.666 amps

Well gee that looks really linear, let's extrapolate. We see a .1v drop for every 1.478 a of load. That would mean that a mere 20 amp load on this battery would drop the voltage to 11.35v, and @ 230 amps, the voltage drop would be 15.56v - much greater than the battery voltage was to start with. Huh. That does not fit the model.

Let's try a 1 ohm resistor. 11.88v Ok, a .1v drop for every 1.234 amp load. No constant here. No linearity at all. In fact, there is evidence of a curve.

Neither linear curve fits, so the battery is not linear.

Now, since this is Graeme I am replying to facts will have to be presented in the original latin, and he may still call me a liar. But I am sure the rest of the readers will understand this.

B.






-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

NickD on Tue September 15, 2009 3:49 PM User is offline

Sulfuric acid batteries are indeed very nonlinear devices, but kind of irrelevant to the OP's problems. Function of the battery is to start the vehicle, filter the output of the alternator, act as a reserve for temporary overloads, and also as a reserve for almost getting you there in the event your alternator decides to die. For normal operation, the alternator supplies the vehicles electrical voltage and can range from 13.8 to 15.5 volts depending on the ambient temperature, 14.5 volts is considered average.

With reduced blower motor performance, the question is, is this voltage getting to the blower motor. This can be tested by checking the voltage drops between the negative terminal of the battery to the negative terminal of the motor and the positive terminal of the battery to the positive terminal of the battery while the blower switch is in the maximum position. Total lines drops should not exceed about 0.2 volts. Engine is running, or if the battery voltage is 14.5 volts across the terminals, the voltage across the blower should be no more than 0.2 volts less, or 14.3 volts in this example.

Another very nonlinear device is the blower motor itself, running all at 14.5 volts, will only draw a couple of amps at most, with the blower wheel attached and running in free air, that current can up to 16 amps, thinking about a Honda in this example, 86 Civic Hatchback to be exact. With the blower installed in the vehicle, and with 14.5 volts applied, mine only drew 10 amps, surface of the evaporator was coated with debris, after a good cleaning, could only get close to 14 amps, due to other restrictions, but better than it was before. Basic physics, with the blower running in either a full or a partial vacuum, it's not doing its full work load, just like cupping your hand on a vacuum cleaner hose. No work, motor speeds up and generates more BEMF that opposes the source voltage so the current drops way down.

That Civic had a very poor MVAC system in it, very large interior, 1.5 L engine, took about ten miles to get any heat out of it, and just a cool breeze from the AC. but what the heck, got great fuel economy and I am tough. But the AC systems in my Supra, Cavalier, DeVille, and even the motorhome, kick butt.

So is this Samurai made for tough guys? Is there a problem with the blower? Or do modifications have to be made?

graeme on Tue September 15, 2009 5:18 PM User is offline

Quote
Originally posted by: bohica2xo
Graeme



1) Your assumptions ignore Ohm's Law.



2) Your assumptions ignore Peukert's Law



3) Your assertions were that the so called measurement would be linear.



4) Without knowing anything about the blower you claim it would draw much more than the headlamps.





Your assertion that the blower should have a voltage drop of 1.6x the headlamps is wrong. The blower in this case is only fused @ 15a, and draws less than that.



A 230 cca battery is rated to provide 230 amps @ 0F, while maintaining a voltage above 7.2v Extrapolating that data to your alleged linear model suggests a voltage drop of .0239 volts per amp of load. So a 10 amp load would represent a .239v drop from 12.7v, for a voltage of 12.461v Your factor of 1.6x voltage drop would be .3824, showing a drop to 12.317 volts.



Sounds great on paper. But a battery is not linear. I took that exact battery to the bench, and loaded it with 10 ohm 25w resistors:



Open circuit battery voltage 12.69v



With 1 10 ohm load 12.42v 1.24 amps



with 2 10 ohm load 12.32v 2.464 amps



with 3 10 ohm load 12.22v 3.666 amps



Well gee that looks really linear, let's extrapolate. We see a .1v drop for every 1.478 a of load. That would mean that a mere 20 amp load on this battery would drop the voltage to 11.35v, and @ 230 amps, the voltage drop would be 15.56v - much greater than the battery voltage was to start with. Huh. That does not fit the model.



Let's try a 1 ohm resistor. 11.88v Ok, a .1v drop for every 1.234 amp load. No constant here. No linearity at all. In fact, there is evidence of a curve.



Neither linear curve fits, so the battery is not linear.



Now, since this is Graeme I am replying to facts will have to be presented in the original latin, and he may still call me a liar. But I am sure the rest of the readers will understand this.



B.

You have yet to tell us anything that qualifies my advice as terrible, you are criticising me for not knowing what the current draw of this fan motor is?- I have no idea what it is meant to be, just giving a very easy way to work out what it is drawing in practice. Given that most people wont have anything more than a multimeter which is not going to be good for anything more than 10A the way Ive given is quick, cheap and effective to get a diagnosis.

Im glad you've done a test on a 230CCA battery. But do the results you have got disqualify the advice Ive given? hardly.

Your tests for loads of 10ohm, 5 ohm ,3.3 ohm by putting resistors in parallel, seem to confirm the near linear relationship, but then you compare that to a result with 1 Ohm, you put ten 10 Ohm resistors in parallel, or you had a 1 ohm rated +/- 3% accuracy resistor handy? that had a power rating of 150+watts? pulling my leg right?

Perhaps you set up 10 resistors in parallel, but not what you have written.

I suspect from previous encounters with your bullying that your only aim was to try and make me look bad?, rather than providing any useful info to the forum

At the end of the day the voltage drop across the battery is going to be a usable measurement to establish how much current it is providing, especially if we suspect a fan is drawing significantly less current than it should.


graeme on Tue September 15, 2009 5:27 PM User is offline

sorry, and I forgot to add Bohica, at the end of the day you actually failed to measure the current flowing through the battery and/or made assumptions that the increase in current made by adding a resistors in parallel was constant, its not as the supply voltage is falling each time.

ScotY on Wed September 16, 2009 6:38 PM User is offlineView users profile

Only had a little free time today but I did a quick test. With the motor off, battery at rest was 12.6v. With the blower on high, voltage measured at the battery terminals was 12.2 to 12.3v. I stuck one probe of the DVM to the blue wire right at the blower motor and the other probe to a clean chassis ground and measured only 9.6v! All tests done with engine OFF. I am going to run a new wire directly to the battery and give that a try. I'm not expecting miracles but it should help noticably if the motor can get a full 12v.

I need to think "old" when I work on this little truck. Otherwise, I'd never think to check stuff like this.

Thanks!
Scot

bohica2xo on Wed September 16, 2009 7:58 PM User is offline

Scot:

Well, there is your answer. A big voltage drop through the old system.

If you are going to the trouble of running a fresh wire direct from the battery, you should add a relay for high speed operation. Use a 12 gauge wire & 15 amp fuse from the battery to feed a relay, and connect the switched side of the relay to the blue wire that feeds the motor. Run the relay coil from the original high speed switch output.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ScotY on Wed September 16, 2009 8:40 PM User is offlineView users profile

Okay, that sounds like a plan! Now, to show my ignorance, how would in wire this up? I understand the relay part of it, just not sure how to integrate into the vehicle. There's a 4 wire plug coming from the blower resistor, 3 positive and one black wire. Each of the positive wires shows different voltage for the slow and medium speed. Do I cut the high speed wire and use this to turn on the relay? Then tap the relay output into the motor blue wire? That would mean I'd have power to the motor via two separate wires? Hope that makes sense?

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