2-Pin 4/blade Fan swap to 3-Pin 6/Blade - Anybody done it ?

[southernman]

Guys, I've got a MK-1 Caddy that came with A/C but has a 2-pin 4 blade assy in it.

I was wondering is it both possible, and advisable, to upgrade to the later 3 pin 6 blade unit ? Again, the truck has AC and I want to use it since I live here in the south where 100+ degree days are the norm...

Also, if it's a doable swap, does anyone have the later model fan assy they want to sell. If yes, PM me.

thanks for any help,

Southernman

[the caveman]

It's possible a 3 pin fan will bolt up to a mk1 shroud, but the blade may to large, if so , maybe switch the blades?

[southernman]

Thanks Caveman. I've looked over the dimensions from both fans and the fan I have measures 280mm. Cross checking, the 3 pin unit also comes in a 280mm OD, which should allow it to bolt right up.

The 4 blade fan is a single speed unit and runs at a constant speed. The other 6 blade units, as I understand it, are 2 speed units that run at low speed when triggered by the temp sensor, and run at high speed when triggered by the "compressor on" relay.

My concern is with the 3-pin connector. I realize I could bypass one of the pins and just run it on high speed, but I'd like to use the 2 speed capability of the 6 blade unit. I don't know why mine, with AC has the 2 pin 4 blade unit on. That may have been how they came.

Anybody out there got a 6 blade, 280mm, unit with the connector still attached ?

Southernman

[R.O.R-2.0]

i think most early mk1s had the single speed 4 blade fan..

the best upgrade you could do, is get the 16v dual fans (both jetta/golf, and passat had duals)

or you can modify a mk3 fan setup to work also. you just have to trim a couple inches off the bottom.

myself personally, i would use the 2 speed thermo switch, and wire it up to use that. then you can use both speeds of the fan..

[southernman]

ROR, I understand your statement about rewiring it for 2 speed operation, which is consistent with my plans. However, you referenced a couple different fans, including the stock unit, and I'm just not clear on which unit you were recommending. Again, thanks for the help !

S

[GEE-BEE]

250 watt scirocco 16 v / two speed
wire to the high speed terminal

I have a 1990 passat dual fan with a 675mm radiator

one fan has a belt driving the other, or you can go to flexalite fan

[R.O.R-2.0]

i think most early mk1s had the single speed 4 blade fan..

the best upgrade you could do, is get the 16v dual fans (both jetta/golf, and passat had duals)

or you can modify a mk3 fan setup to work also. you just have to trim a couple inches off the bottom.

myself personally, i would use the 2 speed thermo switch, and wire it up to use that. then you can use both speeds of the fan..

well, i have a normal mk2 fan in my mk2 car, and it NEVER gets hot.. single 6 blade unit.

my TD rabbit, same deal, good stock fan works fine..

but, if you really want dual rad fans, you can get dual fans off some passats/16v cars that are a direct bolt on to our radiators.

or you can get the dual fan setup off the mk3 cars. but it needs ~2" trimmed off the bottom too make it work on a mk1/2 radiator..

[southernman]

Thanks for the recommendations guys ! I think I'll just start out with the single 6 blade fan as you noted, and should I see any reason to upgrade, I now know which units to look for.

Again, thank you for the advice.

S

[CRSMP5]

ive seen too many mk2 fans eat bearings/bushings they have... cannot say ive ever seen a mk1/mk3 fail though..

your wrong in the assumption that its low speed... then ac triggers high speed.. only triggers high speed when its HOT.. ac on or not.. ac tends to make it HOT to kick it on though... but will start stay in low speed till that temp acheived..

next.. stock mk1 is like high speed.. just a fyi there.. they just did the low/high speed to make it quiet so when you shut the car off you cannot hear the fan run...

which pulls more air.. 6 blade vs 4 blade.. i cannot say.. my mk1s have never had issues.. but i think my 1.6td b3 passat wagon runs about the same.. just cannot hear the fan when you shut it off...

is it worth the extra wiring to fail.. or relays to fail... IMO no...  

[theman53]

That ^ and mine is an MK2 that I have around 30,000 on the engine since rebuild and almost a year of driving it. I think I may have heard the fan kick on 7 times. All of which were when the car was idling without moving at all for at least 10 minutes while I was loading stuff. Except one time on 77 that I was stuck for half an hour and I heard it kick in. Even then they run for about 20 seconds and shut off.

All my MK1's I had were about the same.