Condenser fan 87 Carerra
08-02-2012, 03:38 PM
#1
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Condenser fan 87 Carerra
Has anyone replaced the motor in the condenser fan assembly? I am looking for tips on disassembly and assembly.
Thanks
Thanks
08-02-2012, 05:58 PM
#2
Addict
If it is anything like the other fans on the 911 it isn't that big a deal. Just a couple weeks ago I discovered that one of my foot well fans wasn't working. The squirrel cage was heat-welded to the fan housing. 
What's up with that? Once I got the motor out of the housing I took an exacto knife to the perimeter of the cage then wedged the blade around until it finally came off. It had literally friction welded itself to the housing. Put it all back together and it works fine. Let's hope you are that lucky. 
What's up with that? Once I got the motor out of the housing I took an exacto knife to the perimeter of the cage then wedged the blade around until it finally came off. It had literally friction welded itself to the housing. Put it all back together and it works fine. Let's hope you are that lucky.
08-02-2012, 09:36 PM
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Actually the fan appears to be held to the shaft by a small set screw. It takes a 2mm Allen and is frozen. Looks like soaking the whole fan might be the only way to free it up.
Bill
Bill
08-03-2012, 02:13 PM
#4
Open trunk.
Pull back carpet.
Next to battery is fan housing (black plastic with conical end).
Unplug fan electrical connector.
Remove 4 phillips head screws (don't be surprised if rectangular section
of the base is broken in the corners.
Carefully pull fan back out (inlet tube is in front bumper side).
Place housing on work table.
Remove 4 clips.
At conical plastic end remove phillips head screw and funky large washer.
Split 2 housing sections.
Carefully (applying equal force around the circumference) pull the blower
wheel outward and at the same time push the electrical cord inward until
you can see the male and female spade connectors attached to the motor.
Use a pair of needle nose pliers and wiggle the spade connectors off the motor contacts.
Take some Kano brand Kroil (or your favorite rust buster) and spray
the blower wheel bushing where the motor shaft enters the bushing, top side
and bottom side.
Rotate the blower wheel and exam the fan blades until you locate one with
a small round hole in it; looking inward you will see the location of the
allen set screw in the hub. Spray this with rust buster as well.
Let is sit overnight or at least a few hours, the more the merrier.
Use a long allen key, metric, size I have forgotten for the moment due
improper ratio of Tanqueray/tonic, to extract the allen set screw.
Wipe of the extension of the motor shaft that extends above the blower wheel shaft. Note the distance (amount) the shaft extends out the top of the motor shaft; *you will use this distance later).
Use some sand paper and remove the rust from the shaft
(oxidation on shaft extends the diameter of the shaft vs. the bore hole
in the hub making things difficult).
Locate a bench vise. Open the jaws enough to clear the diameter of the motor. Set the motor down between the jaws until the bottom of the blower wheel is support by the jaws. Use a punch to tap down on the motor's shaft until it exits the blower wheel.
Set blower wheel down on new motor shaft to distance previously measured*. Apply dab of loctite on allen set screw and tighten.
Back to the bench vise: "carefully" set the motor, blower wheel up, in the vise jaws grasping the flats on the bottom of the motor armature, snug up jaws: objective here is to hold the motor carefully without damaging it.
Take a dial indicator on a stand, lock it down on the vise or a plate adjacent to it and position the dial indicator shaft on the top of blower wheel as close to the out circumference as practical. Rotate the blower wheel and use a marker to mark on the wheel either the highest or lowest indicated point.
Using light hand pressure bend the opposite side (of your mark) of the wheel to correct any up and down wobble. Recheck the run out and adjust as needed in an attempt to obtain the least amount of run out (up and down wobble).
Note on the motor housing's end (opposite the blower wheel) there is a tapped (threaded) hold in metal frame end. This should align with the hole in plastic conical end of the blower housing were you previously remove the holding screw. Carefully (not to bend the blower wheel) reinsert the motor back into the blower housing, aligning the motor so that hole mentioned will align. Reattach the electrical wires to the spade terminals on the motor.
Carefully slide the motor in while pulling the excess wire harness out of the housing. Place the funky washer on the housing end, insert the screw, tighten the screw until the motor is pulled into the bottom of the housing.
Reassmble the two housing halves. Reattach the 4 clips.
Remove the old black foam insulation from the rectangular hole in the bottom of the trunk. Use alike material (thin) from big box store (tears, homedeposit, or louse). Put blower back in place. If corners of plastic
of housing are broken use large diameter washers, don't overtighten the phillips screws, just snug them.
Check to see if your year/model has an inline fuse located in the wire harness between the blower motor and fuse panel. If none is obvious
splice in a common inline fuse holder, (red) for the fan motor, (source radioshick) with a 7.5 amp fuse on the hot wire.
Plug in and test. Motor should operate when ign key is in accessory or engine run position, thermostat set to max cold (CW) and evap fan set to
any of the 3 speeds.
If you do not wish to tackle the motor replacement in the housing procedure and you want something a bit more robust, PM us.
Pull back carpet.
Next to battery is fan housing (black plastic with conical end).
Unplug fan electrical connector.
Remove 4 phillips head screws (don't be surprised if rectangular section
of the base is broken in the corners.
Carefully pull fan back out (inlet tube is in front bumper side).
Place housing on work table.
Remove 4 clips.
At conical plastic end remove phillips head screw and funky large washer.
Split 2 housing sections.
Carefully (applying equal force around the circumference) pull the blower
wheel outward and at the same time push the electrical cord inward until
you can see the male and female spade connectors attached to the motor.
Use a pair of needle nose pliers and wiggle the spade connectors off the motor contacts.
Take some Kano brand Kroil (or your favorite rust buster) and spray
the blower wheel bushing where the motor shaft enters the bushing, top side
and bottom side.
Rotate the blower wheel and exam the fan blades until you locate one with
a small round hole in it; looking inward you will see the location of the
allen set screw in the hub. Spray this with rust buster as well.
Let is sit overnight or at least a few hours, the more the merrier.
Use a long allen key, metric, size I have forgotten for the moment due
improper ratio of Tanqueray/tonic, to extract the allen set screw.
Wipe of the extension of the motor shaft that extends above the blower wheel shaft. Note the distance (amount) the shaft extends out the top of the motor shaft; *you will use this distance later).
Use some sand paper and remove the rust from the shaft
(oxidation on shaft extends the diameter of the shaft vs. the bore hole
in the hub making things difficult).
Locate a bench vise. Open the jaws enough to clear the diameter of the motor. Set the motor down between the jaws until the bottom of the blower wheel is support by the jaws. Use a punch to tap down on the motor's shaft until it exits the blower wheel.
Set blower wheel down on new motor shaft to distance previously measured*. Apply dab of loctite on allen set screw and tighten.
Back to the bench vise: "carefully" set the motor, blower wheel up, in the vise jaws grasping the flats on the bottom of the motor armature, snug up jaws: objective here is to hold the motor carefully without damaging it.
Take a dial indicator on a stand, lock it down on the vise or a plate adjacent to it and position the dial indicator shaft on the top of blower wheel as close to the out circumference as practical. Rotate the blower wheel and use a marker to mark on the wheel either the highest or lowest indicated point.
Using light hand pressure bend the opposite side (of your mark) of the wheel to correct any up and down wobble. Recheck the run out and adjust as needed in an attempt to obtain the least amount of run out (up and down wobble).
Note on the motor housing's end (opposite the blower wheel) there is a tapped (threaded) hold in metal frame end. This should align with the hole in plastic conical end of the blower housing were you previously remove the holding screw. Carefully (not to bend the blower wheel) reinsert the motor back into the blower housing, aligning the motor so that hole mentioned will align. Reattach the electrical wires to the spade terminals on the motor.
Carefully slide the motor in while pulling the excess wire harness out of the housing. Place the funky washer on the housing end, insert the screw, tighten the screw until the motor is pulled into the bottom of the housing.
Reassmble the two housing halves. Reattach the 4 clips.
Remove the old black foam insulation from the rectangular hole in the bottom of the trunk. Use alike material (thin) from big box store (tears, homedeposit, or louse). Put blower back in place. If corners of plastic
of housing are broken use large diameter washers, don't overtighten the phillips screws, just snug them.
Check to see if your year/model has an inline fuse located in the wire harness between the blower motor and fuse panel. If none is obvious
splice in a common inline fuse holder, (red) for the fan motor, (source radioshick) with a 7.5 amp fuse on the hot wire.
Plug in and test. Motor should operate when ign key is in accessory or engine run position, thermostat set to max cold (CW) and evap fan set to
any of the 3 speeds.
If you do not wish to tackle the motor replacement in the housing procedure and you want something a bit more robust, PM us.
Last edited by griffiths; 08-03-2012 at 05:07 PM.
08-04-2012, 02:24 PM
#7
Drifting
Or...
You can simply disable the mostly non-functional front blower, NOISY and draws 'way too much power for the low level of functionality, and add 2 modern day ~80W electric radiator cooling fans to force more air downward through the rear lid condensor during engine idle. Wire the new fans so they run any time the compressor clutch is engaged.
An additional upside might be better/improved engine cooling/cooldown in city stop and go traffic as happens with the factory engine compartment fans in the new water cooled cars.
You can simply disable the mostly non-functional front blower, NOISY and draws 'way too much power for the low level of functionality, and add 2 modern day ~80W electric radiator cooling fans to force more air downward through the rear lid condensor during engine idle. Wire the new fans so they run any time the compressor clutch is engaged.
An additional upside might be better/improved engine cooling/cooldown in city stop and go traffic as happens with the factory engine compartment fans in the new water cooled cars.
Trending Topics
08-04-2012, 08:16 PM
#9
Drifting
"..takes a load off..."
No, the exact opposite is true, the rear condensor is "first in line". The more efficient the rear condensor is at extracting HEAT from the compressed refrigerant gas the less work the front condensor will do, can do.
Experience has proven that there is no lack of rear condensor cooling capacity with the engine operating at "cruise" level, and certainly not above. The problem arrises in slow stop and go traffic when it is most likely even the engine itself cannot be kept sufficiently cooled on a HOT Memphis day.
No, the exact opposite is true, the rear condensor is "first in line". The more efficient the rear condensor is at extracting HEAT from the compressed refrigerant gas the less work the front condensor will do, can do.
Experience has proven that there is no lack of rear condensor cooling capacity with the engine operating at "cruise" level, and certainly not above. The problem arrises in slow stop and go traffic when it is most likely even the engine itself cannot be kept sufficiently cooled on a HOT Memphis day.
08-05-2012, 10:40 AM
#11
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"..takes a load off..."
No, the exact opposite is true, the rear condensor is "first in line". The more efficient the rear condensor is at extracting HEAT from the compressed refrigerant gas the less work the front condensor will do, can do.
Experience has proven that there is no lack of rear condensor cooling capacity with the engine operating at "cruise" level, and certainly not above. The problem arrises in slow stop and go traffic when it is most likely even the engine itself cannot be kept sufficiently cooled on a HOT Memphis day.
No, the exact opposite is true, the rear condensor is "first in line". The more efficient the rear condensor is at extracting HEAT from the compressed refrigerant gas the less work the front condensor will do, can do.
Experience has proven that there is no lack of rear condensor cooling capacity with the engine operating at "cruise" level, and certainly not above. The problem arrises in slow stop and go traffic when it is most likely even the engine itself cannot be kept sufficiently cooled on a HOT Memphis day.
08-05-2012, 11:42 AM
#12
Drifting
08-05-2012, 08:47 PM
#14
Drifting
Two 8-10" 80W fans located closest to the condensor HOT inlet will only cover about 1/2 of the rear lid condensor and will do more than an adequate job providing condensor cooling airflow when the engine fan does not.
How much resistance to inlet aiflow does the intercooler cause on the turbo models? And how much PRE-HEATING of the engine cooling airflow does the inetrcooler provide?
How much resistance to inlet aiflow does the intercooler cause on the turbo models? And how much PRE-HEATING of the engine cooling airflow does the inetrcooler provide?
08-06-2012, 11:04 AM
#15
I would venture to guess, depending upon the year of the 911, the avg (varies depending upon the year) liters per second
at 6100 rpms would something like 1335 ls (60 seconds per minute) or 80,100 lm .. per minute.
There are many quotes and charts.
Converted to cfm would be 2828 cfm at 6100 rpms.
The typical 911 condenser is 9"x27.5" of effective area, or 247.5" sq in.
So in a perfect world you might have 2828 cfm pulling across 247 sq in
of condenser at 6100 rpm, and if the correlation between rpm and cfm
was linear it might look something like this:
0 rpm = 0 cfm
1525 rpm = 707 cfm
3050 rpm = 1414 cfm
6100 rpm = 2828 cfm
or ... .46 cfm per rpm
Let's assume at idle, maybe a nominal idle of 850 rpm, the cfm
is equal to 391 cfm (850 x .46). Well use the relationship later on here.
Ideally the largest diameter pancake electric motor puller fan you can mount under the condenser is a 9" nominal. Provided you had a minimum 12vdc and the amps needed, 1 fan pulls 543 cfm under 0 static pressure. However, it is not pulling 543 cfm across the entire condenser:
Effectively 1 fan does not pull 9" of diameter, or 63.6 sq in, across the surface as the fan motor is typically 4.375", or 15 sq in (no fan blades), so the effective surface the fan works on the condenser is 48.6 sq. in.
Let's multiply that by 2 fans for 97" nominal sq in of working area,
or 39% of the condenser area.
Comparing a given surface of the condenser, engine fan at idle vs. electric fan at idle, 391/543, the electric fan is a 38% improvement. But....
Going back to 'at idle', the stock engine cooling fan is pulling 391 cfm across
100% of the condenser surface. Whereas 2 electric fans are pulling 543 cfm across only 39% of the condenser. So, at idle, you are not seeing a 38% improvement with electric fans but rather 38% improvement over only 39% of the total condenser surface. Let's just say for simplicity a 15% improvement at idle using electric fans.
If the electric fan can only pull a maximum of 543 cfm, is it logical that at some point the electric fan could reduce the work done by the engine cooling fan? Logically yes! When the engines cooling fan's cfm exceeds that of the electric fan, that would take place around (543cfm/.46 per rpm) 1180 engine rpms. But wait! ... something else is in play we discussed earlier..
the almost non effective working surface of the electric fan's motor, 15 square inches (x2 fans) 30 square inches is impeding upon the work being done by the engine's fan (or 15/247 or 6% of the engine deck lid condenser is now ineffective because of the electric cooling fan motors).
And, wait... it does get worse...unfortunately:
We assume all cfm's are noted for 'static' pressure. Static pressure in simple terms means there is nothing in front of the fan, no condensers, no deck lid grills, no bugs in the soup. So... above 1180 engine rpms the electric cooling fan's blades become an increase for static pressure (air cannot move as easily past them).
Although car owner 'experience', may feel, or seem or show some improvement when adding electric cooling fans, whether subjective or proven empirically, the reality is that near of just below 1180 rpms,
add on electric cooling fans would only be effective at near idle conditions such as when sitting at traffic lights or in very slow moving (at a crawl) traffic. And, if you were to observe the minutes or hours spent during the course of an average drive while your AC is turned on, that period or percentage of your drive (at or near idle) is probably less than 5% for the average driver.
So, in summary, the idea of adding electric cooling fans under or above the deck lid condenser may sound like a great idea, a simple solution, a less expensive solution, the bottom line is NOPE!
at 6100 rpms would something like 1335 ls (60 seconds per minute) or 80,100 lm .. per minute.
There are many quotes and charts.
Converted to cfm would be 2828 cfm at 6100 rpms.
The typical 911 condenser is 9"x27.5" of effective area, or 247.5" sq in.
So in a perfect world you might have 2828 cfm pulling across 247 sq in
of condenser at 6100 rpm, and if the correlation between rpm and cfm
was linear it might look something like this:
0 rpm = 0 cfm
1525 rpm = 707 cfm
3050 rpm = 1414 cfm
6100 rpm = 2828 cfm
or ... .46 cfm per rpm
Let's assume at idle, maybe a nominal idle of 850 rpm, the cfm
is equal to 391 cfm (850 x .46). Well use the relationship later on here.
Ideally the largest diameter pancake electric motor puller fan you can mount under the condenser is a 9" nominal. Provided you had a minimum 12vdc and the amps needed, 1 fan pulls 543 cfm under 0 static pressure. However, it is not pulling 543 cfm across the entire condenser:
Effectively 1 fan does not pull 9" of diameter, or 63.6 sq in, across the surface as the fan motor is typically 4.375", or 15 sq in (no fan blades), so the effective surface the fan works on the condenser is 48.6 sq. in.
Let's multiply that by 2 fans for 97" nominal sq in of working area,
or 39% of the condenser area.
Comparing a given surface of the condenser, engine fan at idle vs. electric fan at idle, 391/543, the electric fan is a 38% improvement. But....
Going back to 'at idle', the stock engine cooling fan is pulling 391 cfm across
100% of the condenser surface. Whereas 2 electric fans are pulling 543 cfm across only 39% of the condenser. So, at idle, you are not seeing a 38% improvement with electric fans but rather 38% improvement over only 39% of the total condenser surface. Let's just say for simplicity a 15% improvement at idle using electric fans.
If the electric fan can only pull a maximum of 543 cfm, is it logical that at some point the electric fan could reduce the work done by the engine cooling fan? Logically yes! When the engines cooling fan's cfm exceeds that of the electric fan, that would take place around (543cfm/.46 per rpm) 1180 engine rpms. But wait! ... something else is in play we discussed earlier..
the almost non effective working surface of the electric fan's motor, 15 square inches (x2 fans) 30 square inches is impeding upon the work being done by the engine's fan (or 15/247 or 6% of the engine deck lid condenser is now ineffective because of the electric cooling fan motors).
And, wait... it does get worse...unfortunately:
We assume all cfm's are noted for 'static' pressure. Static pressure in simple terms means there is nothing in front of the fan, no condensers, no deck lid grills, no bugs in the soup. So... above 1180 engine rpms the electric cooling fan's blades become an increase for static pressure (air cannot move as easily past them).
Although car owner 'experience', may feel, or seem or show some improvement when adding electric cooling fans, whether subjective or proven empirically, the reality is that near of just below 1180 rpms,
add on electric cooling fans would only be effective at near idle conditions such as when sitting at traffic lights or in very slow moving (at a crawl) traffic. And, if you were to observe the minutes or hours spent during the course of an average drive while your AC is turned on, that period or percentage of your drive (at or near idle) is probably less than 5% for the average driver.
So, in summary, the idea of adding electric cooling fans under or above the deck lid condenser may sound like a great idea, a simple solution, a less expensive solution, the bottom line is NOPE!